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Objectives: In subsistence populations, high physical activity is typically maintained throughout pregnancy. Market integration shifts activity patterns to resemble industrialized populations, with more time allocated to sedentary behavior. Daasanach semi-nomadic pastoralists living in northern Kenya face lifestyle heterogeneity due to the emergence of a market center. We investigate how Daasanach women manage the energetic demands of pregnancy with subsistence labor tasks and how market integration relates to variation in energetic demands, physical activity, and coping strategies., Methods: We conducted nine focus group discussions with 72 pregnant women. We also deployed wrist-worn fitness trackers with 21 pregnant women in two community types: central or peripheral to the market center to capture variation in market integration. Data from focus group discussions were analyzed using thematic analysis. We used multiple linear regression to examine the relationship between gestational age and physical activity., Results: We identified themes of increased fatigue, diet restrictions, and assistance with labor tasks during pregnancy. Gestational age negatively predicted mean daily steps, with a decrease of 1160 ± 437 steps per day with each consecutive pregnancy month. Stratified by community type, gestational age only negatively predicted mean daily steps for peripheral communities, with a decrease of 1443 ± 629 steps per day with each consecutive pregnancy month., Conclusions: Results suggest that physical activity differs with market integration early, but not late, in pregnancy. Daasanach women cope with the energetic demands of pregnancy by reducing physical activity late in pregnancy and receiving assistance with labor tasks from family and neighbors., (© 2024 Wiley Periodicals LLC.)

Climate change is triggering environmental mobility through chronic water problems and punctuated events. Thinking about moving locations, or "mobility ideation", is the precursor to migration intentionality and actual migration. Drawing on the embodiment construct, this study examines how the worst drought in recent history in the Horn of Africa affected water-related mobility ideation and, in turn, fingernail cortisol concentration (FCC), a chronic stress biomarker, among Daasanach semi-nomadic pastoralists in northern Kenya. To address these questions, we primarily draw on survey, anthropometric, water quality, and biomarker data among 175 adults living in seven communities in 2022. We used mixed-effects ordered logistic regression to test how livestock wealth, water insecurity, food insecurity, and anxiety/depression symptom scores were associated with household mobility ideation. We then used generalized linear models to test the association between mobility ideation on FCC. Thinking about moving at least once due to water problems increased from pre-drought in 2019 (55%) to during the drought in 2022 (92%), while actual mobility declined. Livestock wealth, while associated with actual mobility in the prior year, was protective against increased mobility ideation, while water insecurity, food insecurity, and anxiety/depression symptoms were associated with greater odds of thinking of leaving in 2022. Compared to adults who did not consider moving, those who considered moving rarely, sometimes, and often had FCC levels 18.1% higher (95% CI, 1.01-1.38; p = 0.039), 19.4% higher (1.01-1.41; p = 0.040), and 32.3% higher (1.01-1.73; p = 0.039), respectively, with results consistent in sensitivity analyses. Extreme climatic events in water scarce regions may increase mobility ideation through worsened experiential indicators of well-being and resource insecurity. Mobility ideation may capture measures of adversity suffered by pastoralists and signify climate distress. This research broadens understanding of how droughts get under the skin by leading to resource insecurity and triggering thoughts of moving, which increases chronic stress., Competing Interests: Declaration of competing interest The authors declare they have no conflicts of interest., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Globally, challenges with water and food are two of the most pressing problems people face. Yet hydrologically water-rich environments and rural environments are often overlooked in these discussions due to abundance of natural water resources. Here we test the relationship between water and food insecurity among 270 Tsimane' households in the Bolivian Amazon. Water challenges were evaluated with the Household Water Insecurity Experiences Scale (HWISE), water quality perception, objective water quality analyses, and water access via the JMP drinking water ladder. Food insecurity was measured with the Household Food Insecurity Access Scale (HFIAS), and quantitative measures of food frequency recall were used to further test the water and food insecurity relationship. Using multilevel mixed-effects linear regression, each point increase in HWISE score was associated with 0.47 point (95 % CI: 0.30, 0.62, p < 0.001) higher food insecurity, and households with access to improved water sources had between 1.25 and 1.36 points (95 % CI: -2.61, -0.01, p < 0.05) lower food insecurity compared to households reliant on surface water. These relationships held true independent of quantitative measures of both fish and meat consumption. Using mixed-effects logistic regression analyses, each point increase in HWISE score was associated with 43 % (95 % CI: 1.25-1.66, p < 0.001) increased odds of experiencing severe food insecurity. Households changing what was eaten due to experienced water problems was associated with 2.33 points (95 % CI: 0.41, 4.25, p < 0.05) higher food insecurity. This relationship held true independent of perceived water quality, indicating other structural water problems may be important here in the household water and food insecurity relationship. These results demonstrate that even in water-rich environments, like the Amazon, water and food insecurity are interconnected. Further, despite the challenging conditions, equitable structural interventions, like the development of improved water infrastructure, are critical for the provision of clean drinking water and may simultaneously help alleviate food insecurity., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Objective: Hydration status and water intake are critical to physiological health. Despite a popular narrative that dehydration impairs cognitive performance, results are mixed in the literature. Therefore, we tested how hydration status was associated with cognitive performance in an ad libitum state over the course of 3 months., Methods: Data come from a short-term longitudinal study among middle-to-older aged US adults (n = 78) measured three times (207 observations). All participants were scheduled for 8:00 a.m. visits for the baseline, two-week, and 3-month examinations where they completed surveys, neuropsychological tests to measure cognitive performance, anthropometrics, and a blood draw for biomarker analysis. Serum osmolality (Sosm) was measured as a biomarker of hydration status using osmometry. Four cognitive performance tasks were assessed, including inhibition, working memory, cognitive flexibility, and sustained attention., Results: Panel random effects linear regressions demonstrate that there was an inverse association between dehydration and sustained attention, whereas there were no significant relationships between dehydration and inhibition, working memory, and cognitive flexibility. Adults who were dehydrated (defined as Sosm >300 mOsm/kg) performed substantially worse (B = 0.65 z-score; SE = 0.28; p = .020) on the sustained attention task than those who were not dehydrated adjusting for time fixed effects, age, body mass index, sex, and educational attainment., Conclusion: This short-term longitudinal study found that dehydration was only associated with poorer performance on a cognitive performance task that required sustained attention. Maintaining adequate hydration may be increasingly important for middle-to-older aged adults to ensure proper cognitive function, particularly as water needs increase in future climatic scenarios., (© 2024 The Authors. American Journal of Human Biology published by Wiley Periodicals LLC.)

Maintaining adequate hydration over the course of pregnancy is critical for maternal and fetal health and reducing risks for adverse pregnancy outcomes (e.g., preeclampsia, low placental and amniotic fluid volume). Recent evidence suggests that women may be at risk for under-hydration in the second and third trimesters when water needs begin to increase. Scant research has examined pregnant women's knowledge of hydration recommendations, water intake behaviors, and willingness to use digital tools to promote water intake. This study aimed to: 1) describe hydration recommendation knowledge and behaviors by the overall sample and early vs late pregnancy, and 2) identify habits and barriers of using digital tools. Pregnant women (N = 137; M age = 30.9 years; M gestational age = 20.9) completed a one-time, 45-minute online survey. Descriptive statistics quantified women's knowledge of hydration recommendations, behaviors, and attitudes about utilizing digital tools to promote adequate intake, and Mann-Whitney U and chi-squared tests were used to determine group differences. Most women lacked knowledge of and were not meeting hydration recommendations (63%, 67%, respectively) and were not tracking their fluid consumption (59%). Knowledge of hydration recommendations differed by time of pregnancy, such that women in later pregnancy reported 82 ounces compared to women in early pregnancy (49 ounces). Common barriers included: forgetting to drink (47%), not feeling thirsty (47%), and increased urination (33%). Most were willing to use digital tools (69%) and believed a smart water bottle would help them achieve daily fluid recommendations (67%). These initial findings suggest that pregnant women may benefit from useful strategies to increase knowledge, decrease barriers, and maintain adequate hydration, specifically earlier in pregnancy. These findings will inform the design of a behavioral intervention incorporating smart connected water bottles, wearables for gesture detection, and behavior modification strategies to overcome barriers, promote proper hydration and examine its impact on maternal and infant health outcomes., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Pauley et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Pastoralists live in challenging environments, which may be accompanied by unique activity, energy, and water requirements., Aim: Few studies have examined whether the demands of pastoralism contribute to differences in total energy expenditure (TEE) and water turnover (WT) compared to other lifestyles., Subjects and Methods: Accelerometer-derived physical activity, doubly labelled water-derived TEE and WT, and anthropometric data were collected for 34 semi-nomadic Daasanach adults from three northern Kenyan communities with different levels of pastoralist activity. Daasanach TEEs and WTs were compared to those of other small-scale and industrialised populations., Results: When modelled as a function of fat-free-mass, fat-mass, age, and sex, TEE did not differ between Daasanach communities. Daasanach TEE (1564-4172 kcal/day) was not significantly correlated with activity and 91% of TEEs were within the range expected for individuals from comparison populations. Mean WT did not differ between Daasanach communities; Daasanach absolute (7.54 litres/day men; 7.46 litres/day women), mass-adjusted, and TEE-adjusted WT was higher than most populations worldwide., Conclusions: The similar mass-adjusted TEE of Daasanach and industrialised populations supports the hypothesis that habitual TEE is constrained, with physically demanding lifestyles necessitating trade-offs in energy allocation. Elevated WT in the absence of elevated TEE likely reflects a demanding active lifestyle in a hot, arid climate.

Objectives: Short sleep duration is associated with poor physical health in college students. Few studies examine the effects of sleep extension on physical health in this population, who are susceptible to sleep loss. We examined health effects of a 1-week, 1-hour nightly sleep extension in college students., Methods: Twelve healthy undergraduate college students (83% female; age 20.2 ± 1.5years) completed a study consisting of sleeping typically for 1week ("Habitual"), then extending sleep by ≥1 hour/night during the second week ("Extension"). Sleep and physical activity actigraphy were collected throughout. Following each week, participants completed cardiometabolic assessments including a meal response and provided a urine sample for markers of hydration., Results: In Extension compared to Habitual, average sleep duration increased (mean change±SEM, +42.6 ± 15.1 minutes; p = .005), while subjective sleepiness (-1.8 ± 0.8 units; p = .040), systolic blood pressure (-6.6 ± 2.8 mmHg; p = .037), postprandial glucose area under the curve (-26.5 ± 10.2 mg/dL × h; p = .025) and time to baseline (-83.0 ± 46.4 minutes; p = .031) after the meal response, sedentary time (-44.3 ± 15.7 minutes; p = .018), and percentage of wake in moderate-to-vigorous activity (-0.89% ± 0.35%; p = .030) decreased. Participants who increased average sleep duration by ≥20 minutes (n = 9) were better hydrated according to urine osmolality (-187.0 ± 68.4 mOsm/kg; p = .026) and specific gravity (-0.01 ± 0.002 g/mL; p = .012) and had reduced odds of dehydration according to urine osmolality (≥800 mOsm/kg; -67%; OR=0.03; p = .035)., Conclusions: This pilot study's findings suggest that sleep extension may improve cardiometabolic functioning and hydration, and alter sedentary behavior and physical activity, in college students. Sleep extension may be employed to improve multiple aspects of health in this sleep-deprived population., Competing Interests: Declaration of conflicts of interest None of the authors have conflicts of interests related to the material presented. Outside of the current work, DA is supported by the Prevention and Methodology Training Program (T32 DA017629) with funding from the National Institute on Drug Abuse. A-MC has received a grant to the Pennsylvania State University from Kunasan and honoraria/travel support for lectures from University of Miami., (Copyright © 2024 National Sleep Foundation. Published by Elsevier Inc. All rights reserved.)

Background and Objectives: Non-communicable disease risk and the epidemic of cardiometabolic diseases continue to grow across the expanding industrialized world. Probing the relationships between evolved human physiology and modern socioecological conditions is central to understanding this health crisis. Therefore, we investigated the relationships between increased market access, shifting subsistence patterns and cardiometabolic health indicators within Daasanach semi-nomadic pastoralists who vary in their engagement in traditional lifestyle and emerging market behaviors., Methodology: We conducted cross-sectional socioecological, demographic and lifestyle stressor surveys along with health, biomarker and nutrition examinations among 225 (51.6% female) Daasanach adults in 2019-2020. We used linear mixed-effects models to test how differing levels of engagement in market integration and traditional subsistence activities related to blood pressure (BP), body composition and blood chemistry., Results: We found that systolic and diastolic BP, as well as the probability of having high BP (hypertension), were negatively associated with distance to market, a proxy for market integration. Additionally, body composition varied significantly by socioeconomic status (SES), with significant positive associations between BMI and body fat and higher SES among adults., Conclusions and Implications: While evidence for evolutionary mismatch and health variation have been found across a number of populations affected by an urban/rural divide, these results demonstrate the effects of market integration and sedentarization on cardiometabolic health associated with the early stages of lifestyle changes. Our findings provide evidence for the changes in health when small-scale populations begin the processes of sedentarization and market integration that result from myriad market pressures., Competing Interests: None declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Foundation for Evolution, Medicine, and Public Health.)

Purpose: Suboptimal hydration has been linked to a variety of adverse health outcomes. Few studies have examined the impact of hydration status on immune function, a plausible physiological mechanism underlying these associations. Therefore, we tested how variation in hydration status was associated with circulating pro-inflammatory cytokine levels and ex vivo lipopolysaccharide (LPS)-stimulated pro-inflammatory cytokine production., Methods: Blood samples were obtained from a community sample of healthy middle-to-older-aged adults (N = 72). These samples were used to assess serum osmolality, a biomarker of hydration status, and markers of immune function including circulating pro-inflammatory cytokines and stimulated pro-inflammatory cytokine production after 4 and 24 h of incubation with LPS. Multiple linear regressions were used to test the association between serum osmolality (as a continuous variable) and markers of immune function at baseline and after 4 and 24 h adjusting for age, sex, and BMI. These models were re-estimated with serum osmolality dichotomized at the cut-off for dehydration (> 300 mOsm/kg)., Results: While not significantly associated with circulating cytokines (B = - 0.03, p = 0.09), serum osmolality was negatively associated with both 4 h (B = - 0.05, p = 0.048) and 24 h (B = - 0.05, p = 0.03) stimulated cytokine production when controlling for age, sex, and BMI. Similarly, dehydration was associated with significantly lower cytokine production at both 4 h (B = - 0.54, p = 0.02) and 24 h (B = - 0.51, p = 0.02) compared to adequate hydration., Conclusion: These findings suggest that dehydration may be associated with suppressed immune function in generally healthy middle-to-older aged community-dwelling adults. Further longitudinal research is needed to more clearly define the role of hydration in immune function., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.)

Objectives: Investigations of early childhood growth among small-scale populations are essential for understanding human life history variation and enhancing the ability to serve such communities through global public health initiatives. This study characterizes early childhood growth trajectories and identifies differences in growth patterns relative to international references among Daasanach semi-nomadic pastoralist children living in a hot, arid region of northern Kenya., Methods: A large sample of height and weight measures were collected from children (N = 1756; total observations = 4508; age = 0-5 years) between 2018 and 2020. Daasanach growth was compared to international reference standards and Daasanach-specific centile growth curves and pseudo-velocity models were generated using generalized additive models for location scale and size., Results: Compared to World Health Organization (WHO) reference, relatively few Daasanach children were stunted (14.3%), while a large proportion were underweight (38.5%) and wasted (53.6%). Additionally, Daasanach children had a distinctive pattern of growth, marked by an increase in linear growth velocity after 24 months of age and relatively high linear growth velocity throughout the rest of early childhood., Conclusions: These results identify a unique pattern of early childhood growth faltering among children in a small-scale population and may reflect a thermoregulatory adaptation to their hot, arid environment. As linear growth and weight gain remain important indicators of health, the results of this study provide insight into growth velocity variations. This study has important implications for global public health efforts to identify and address sources of early growth faltering and undernutrition in small-scale populations., (© 2022 Wiley Periodicals LLC.)

Objective: Water plays a critical role in the production of food and preparation of nutritious meals, yet few studies have examined the relationship between water and food insecurity. The primary objective of this study, therefore, was to examine how experiences of household water insecurity (HWI) relate to experiences of household food insecurity (HFI) among a pastoralist population living in an arid, water-stressed region of northern Kenya., Design: We implemented the twelve-item Household Water Insecurity Experiences (HWISE, range 0-36) Scale and the nine-item Household Food Insecurity Access Scale (HFIAS, range 0-27) in a cross-sectional survey to measure HWI and HFI, respectively. Data on socio-demographic characteristics and intake of meat and dairy in the prior week were collected as covariates of interest., Setting: Northern Kenya, June-July 2019., Participants: Daasanach pastoralist households ( n 136) from seven communities., Results: In the prior 4 weeks, 93·4 % and 98·5 % of households had experienced moderate-to-severe HWI and HFI, respectively. Multiple linear regression analyses indicated a strong association between HWI and HFI. Each point higher HWISE score was associated with a 0·44-point (95 % CI: 0·22, 0·66, P = 0·003) higher HFIAS score adjusting for socio-economic status and other covariates., Conclusions: These findings demonstrate high prevalence and co-occurrence of HWI and HFI among Daasanach pastoralists in northern Kenya. This study highlights the need to address HWI and HFI simultaneously when developing policies and interventions to improve the nutritional well-being of populations whose subsistence is closely tied to water availability and access.

Extreme climatic events are increasing in frequency, leading to hotter temperatures, flooding, droughts, severe storms, and rising oceans. This special issue brings together a collection of seven articles that describe the impacts of extreme climatic events on a diverse set of human biology and health outcomes. The first two articles cover extreme temperatures extending from extreme heat to cold and changes in winter weather and the respective implications for adverse health events, human environmental limits, well-being, and human adaptability. Next, two articles cover the effects of exposures to extreme storms through an examination of hurricanes and cyclones on stress and birth outcomes. The following two articles describe the effects of extreme flooding events on livelihoods, nutrition, water and food insecurity, diarrheal and respiratory health, and stress. The last article examines the effects of drought on diet and food insecurity. Following a brief review of each extreme climatic event and articles covered in this special issue, I discuss future research opportunities-highlighting domains of climate change and specific research questions that are ripe for biological anthropologists to investigate. I close with a description of interdisciplinary methods to assess climate exposures and human biology outcomes to aid the investigation of the defining question of our time - how climate change will affect human biology and health. Ultimately, climate change is a water, food, and health problem. Human biologists offer a unique perspective for a combination of theoretical, methodological, and applied reasons and thus are in a prime position to contribute to this critical research agenda., (© 2022 Wiley Periodicals LLC.)

Objectives: Flooding is the most frequent extreme-weather disaster and disproportionately burdens marginalized populations. This article examines how food and water insecurity, blood pressure (BP), nutritional status, and diarrheal and respiratory illnesses changed during the 2 months following a historic flood in lowland Bolivia., Methods: Drawing on longitudinal data from Tsimane' forager-horticulturalist (n = 118 household heads; n = 129 children) directly after a historic 2014 flood and ~2 months later, we use fixed effects linear regression and random effects logistic regression models to test changes in the markers of well-being and health over the recovery process., Results: Results demonstrated that water insecurity scores decreased significantly 2 month's postflood, while food insecurity scores remained high. Adults' systolic and diastolic BP significantly declined 2 months after the flood's conclusion. Adults experienced losses in measures of adiposity (BMI, sum of four skinfolds, waist circumference). Children gained weight and BMI-for-age Z-scores indicating buffering of children by adults from food stress that mainly occurred in the community closer to the main market town with greater access to food aid. Odds of diarrhea showed a nonsignificant decline, while cough increased significantly for both children and adults 2 months postflood., Conclusions: Water insecurity and BP improved during the recovery process, while high levels of food insecurity persisted, and nutritional stress and respiratory illness worsened. Not all indicators of well-being and health recover at the same rate after historic flooding events. Planning for multiphase recovery is critical to improve health of marginalized populations after flooding., (© 2022 Wiley Periodicals LLC.)

This article quantifies Daasanach water insecurity experiences in Northern Kenya, examines how water insecurity is associated with water borrowing and psychosocial stress, and evaluates if water borrowing mitigates the stress from water insecurity. Of 133 households interviewed in 7 communities, 94% were water insecure and 74.4% borrowed water three or more times in the prior month. Regression analyses demonstrate water borrowing frequency moderates the relationship between water insecurity and psychosocial stress. Only those who rarely or never borrowed water reported greater stress with higher water insecurity. The coping mechanism of water borrowing may help blunt water insecurity-related stress., Competing Interests: None of the authors have a conflict of interest to declare.

Background: Food insecurity has profound nutritional and public health consequences. Water insecurity may exacerbate food insecurity, yet little is known about the association between water and food insecurity in the United States or other high-income countries., Objective: This study aimed to estimate how tap water avoidance, a proxy of water insecurity, covaries with food insecurity; examine how the probability of food insecurity changed by tap water avoidance between 2005 and 2018; and test how the association between tap water avoidance and food insecurity differed across income and housing statuses., Design: This was a secondary analysis of the cross-sectional 2005-2018 National Health and Nutrition Examination Survey., Participants/setting: Participants were 31,390 US adults 20 years and older., Main Outcome Measures: The main outcome was food insecurity, using the US Food Security Survey Module., Statistical Analyses: Adjusted logistic regression models estimated how tap water avoidance was associated with the odds of food insecurity. Predicted probabilities of food insecurity over time and by income and housing status were plotted using marginal standardization., Results: Adults who avoided tap water had 21% higher odds (95% CI 1.09 to 1.34) of food insecurity compared with those who drank tap water. The probability of any food insecurity doubled between 2005-2006 and 2017-2018 and was consistently higher for tap water avoiders. Food insecurity decreased across both tap water drinkers and avoiders as income increased, but was higher among tap water avoiders at all income levels. Likewise, food insecurity was higher among renters than among homeowners but was higher among tap water avoiders in both housing groups., Conclusions: Tap water avoidance is positively associated with food insecurity in the United States, and both insecurities have increased over time. Efforts to mitigate food insecurity should simultaneously address water insecurity issues, including tap water availability and quality, as these may be a modifiable contributors to food insecurity., (Copyright © 2023 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.)

Objectives: To assess the association between sugar from sugar-sweetened beverages (SSBs) and untreated decay in permanent teeth and calculate the cost burden of sugar from SSBs on untreated decay in US adults., Methods: Cross-sectional data from the 2013-2014 and 2015-2016 cycles of the National Health and Nutrition Examination Survey (NHANES) were analysed in 2020 (n = 9001 adults aged ≥20). Multivariable analyses assessed sugar intake from SSB consumption with the presence of untreated decay in permanent teeth and number of untreated decayed teeth. Population attributable risk was used to estimate the cost burden arising from SSBs on untreated decay in US adults., Results: One fourth (25.1%) of US adults had untreated dental decay, and higher prevalence was observed among those with low income, low education and race/ethnicity of non-Hispanic Black. Overall, 53% of adults reported no intake of SSBs. For the remaining 47%, the median 24-h intake was 46.8 g of sugar from SSBs. The adjusted prevalence ratio (PR) for untreated decay was 1.3 (95% confidence interval [CI] 1.1-1.5) for consumption of 46.8 g or more of sugar from SSBs compared to those reporting no sugar from SSBs. Number of untreated decayed teeth increased with sugar intake from SSBs from lowest to highest tertile: 0.1, (p = .35); 0.4, (p = .006); and 0.6, (p < .001). The cost burden of untreated decay attributable to SSBs in US adults is estimated conservatively at $1.6 billion USD., Conclusions: Community level interventions directed at sugar from SSBs are justified to address disparities in the burden of untreated dental decay., (© 2021 The Authors. Community Dentistry and Oral Epidemiology published by John Wiley & Sons Ltd.)

Objectives: Thirst is an evolved central homeostatic feedback system that helps regulate body water for survival. Little research has examined how early development and exposure to extreme environments and water availability affect thirst perception, particularly outside Western settings. Therefore, we compared two indicators of perceived thirst (current thirst and pleasantness of drinking water) using visual scales among Tsimane' forager-horticulturalists in the hot-humid Bolivian Amazon and Daasanach agro-pastoralists in hot-arid Northern Kenya., Methods: We examined how these measures of perceived thirst were associated with hydration status (urine specific gravity), ambient temperatures, birth season, age, and population-specific characteristics for 607 adults (n = 378 Tsimane', n = 229 Daasanach) aged 18+ using multi-level mixed-effect regressions., Results: Tsimane' had higher perceived thirst than Daasanach. Across populations, hydration status was unrelated to both measures of thirst. There was a significant interaction between birth season and temperature on pleasantness of drinking water, driven by Kenya data. Daasanach born in the wet season (in utero during less water availability) had blunted pleasantness of drinking water at higher temperatures compared to those born in the dry season (in utero during greater water availability)., Conclusions: Our findings suggest hydration status is not a reliable predictor of thirst perceptions in extreme-hot environments with ad libitum drinking. Rather, our findings, which require additional confirmation, point to the importance of water availability during gestation in affecting thirst sensitivity to heat and water feedback mechanisms, particularly in arid environments. Thirst regulation will be increasingly important to understand given climate change driven exposures to extreme heat and water insecurity., (© 2021 Wiley Periodicals LLC.)

Anthropological theories of reciprocity suggest it enhances prestige, social solidarity, and material security. Yet, some ethnographic cases suggest that water sharing-a form of reciprocity newly gaining scholarly attention-might work in the opposite way, increasing conflict and emotional distress. Using cross-cultural survey data from twenty global sites (n=4,267), we test how household water reciprocity (giving and receiving) is associated with negative emotional and social outcomes. Participation in water sharing as both givers and receivers is consistently associated with greater odds of reporting shame, upset, and conflict over water. Water sharing experiences in a large, diverse sample confirm a lack of alignment with predictions of classic reciprocity theories. Recent ethnographic research on reciprocity in contexts of deepening contemporary poverty will allow development of ethnographically informed theories to better explain negative experiences tied to water reciprocity.

Background: In the United States, problems with the provision of safe, affordable water have resulted in an increasing number of adults who avoid their tap water, which could indicate underlying water insecurity. Dietary recalls provide critical nutritional surveillance data, yet have been underexplored as a water insecurity monitoring tool., Objectives: This article aims to demonstrate how water intake variables from dietary recall data relate to and predict a key water insecurity proxy, that is, tap water avoidance., Methods: Using 2005-2018 NHANES data from 32,329 adults, I examine distributions and trends of mean intakes of total, plain (sum of tap and bottled water), tap, and bottled water, and percentage consuming no tap and exclusive bottled water. Second, I use multiple linear and logistic regressions to test how tap water avoidance relates to plain water intake and sugar-sweetened beverage (SSB) consumption. Next, I use receiver operating characteristics (ROC) curves to test the predictive accuracy of no plain water, no tap, and exclusive bottled water intake, and varying percentages of plain water consumed from tap water compared with tap water avoidance., Results: Trends indicate increasing plain water intake between 2005 and 2018, driven by increasing bottled water intake. In 2017-18, 51.4% of adults did not drink tap water on a given day, whereas 35.8% exclusively consumed bottled water. Adults who avoided their tap water consumed less tap and plain water, and significantly more bottled water and SSBs on a given day. No tap intake and categories of tap water intake produced 77% and 78% areas under the ROC curve in predicting tap water avoidance., Conclusions: This study demonstrates that water intake variables from dietary recalls can be used to accurately predict tap water avoidance and provide a window into water insecurity. Growing reliance on bottled water could indicate increasing concerns about tap water., (© The Author(s) 2022. Published by Oxford University Press on behalf of the American Society for Nutrition.)

Objective: As tap water distrust has grown in the USA with greater levels among Black and Hispanic households, we aimed to examine recent trends in not drinking tap water including the period covering the US Flint Water Crisis and racial/ethnic disparities in these trends., Design: Cross-sectional analysis. We used log-binomial regressions and marginal predicted probabilities to examine US nationally representative trends in tap and bottled water consumption overall and by race/ethnicity., Setting: The National Health and Nutrition Examination Survey data, 2011-2018., Participants: Nationally representative sample of 9439 children aged 2-19 years and 17 268 adults., Results: Among US children and adults, respectively, in 2017-2018 there was a 63 % (adjusted prevalence ratio (PR): 1·63, 95 % CI (1·25, 2·12), P < 0·001)) and 40 % (PR: 1·40, 95 % CI (1·16, 1·69), P = 0·001)) higher prevalence of not drinking tap water compared to 2013-2014 (pre-Flint Water Crisis). For Black children and adults, the probability of not drinking tap water increased significantly from 18·1 % (95 % CI (13·4, 22·8)) and 24·6 % (95 % CI (20·7, 28·4)) in 2013-2014 to 29·3 % (95 % CI (23·5, 35·1)) and 34·5 % (95 % CI (29·4, 39·6)) in 2017-2018. Among Hispanic children and adults, not drinking tap water increased significantly from 24·5 % (95 % CI (19·4, 29·6)) and 27·1 % (95 % CI (23·0, 31·2)) in 2013-2014 to 39·7 % (95 % CI (32·7, 46·8)) and 38·1 % (95 % CI (33·0, 43·1)) in 2017-2018. No significant increases were observed among Asian or White persons between 2013-2014 and 2017-2018. Similar trends were found in bottled water consumption., Conclusions: This study found persistent disparities in the tap water consumption gap from 2011 to 2018. Black and Hispanics' probability of not drinking tap water increased following the Flint Water Crisis.

Purpose: Water needs increase during pregnancy, and proper hydration is critical for maternal and fetal health. This study characterized weekly hydration status changes throughout pregnancy and examined change in response to a randomized, behavioral intervention. An exploratory analysis tested how underhydration during pregnancy was associated with birth outcomes., Methods: The Healthy Mom Zone Study is a longitudinal, randomized-control trial intervention aiming to regulate gestational weight gain (GWG) in pregnant women with overweight/obesity (n = 27). Fourteen women received standard of care; 13 women additionally received weekly guidance on nutrition, physical activity, water intake, and health-promoting behaviors. Hydration status was measured weekly via overnight urine osmolality (Uosm) from ~ 8-36 weeks gestation; underhydration was dichotomized (Uosm ≥ 500 mOsm/kg). Gestational age- and sex-standardized birth weight and length z scores and percentiles were calculated. We used mixed-effect and linear regression models to test covariate-adjusted relationships., Results: No differences existed in Uosm or other characteristics between control and intervention women at baseline. Significant interactions (p = 0.01) between intervention and week of pregnancy on Uosm indicated intervention women maintained lower Uosm, whereas control women had a significant quadratic (inverse-U) relationship and greater Uosm in the second and early third trimesters. Results were consistent across robustness and sensitivity checks. Exploratory analyses suggest underhydration was associated with birth weight, but not length, in opposite ways in the second vs. third trimester., Conclusion: A multi-component behavioral intervention helped women with overweight/obesity maintain better hydration throughout pregnancy. Future studies should confirm birth outcome results as they have important implications for early life nutrition., Trial Registration: ClinicalTrials.gov Identifier: NCT03945266; registered May 10, 2019 retrospectively., (© 2021. Springer-Verlag GmbH Germany, part of Springer Nature.)

Water is critical to health and wellbeing. Studies have theorized that problems with water can become embodied, yet few studies have quantified this. Therefore, we first sought to understand the lowland Bolivian water environment of Tsimane' forager-horticulturalists. We assessed the water environment holistically, using objective measures of water quality and water services (Joint Monitoring Programme's drinking water services ladder) and subjective measures, including perceived water safety and water insecurity experiences [Household Water Insecurity Experiences Scale (HWISE)]. We tested how water service levels, perceived water safety, and water fetching frequency were associated with HWISE scores using Tobit regression models among 270 households. We then tested if and how water becomes embodied via self-reported water-related injury and a chronic stress biomarker, hair cortisol concentration (HCC). Results demonstrated that, compared with households using surface water, households with basic water services had HWISE scores 1.59-pts lower (SE = 0.29; P < 0.001). Ingestion of water perceived to be "bad" and more daily water-fetching trips were associated with higher HWISE scores. Twenty percent of households reported prior water-related injuries, with women most commonly injured. In logistic regressions, each point higher HWISE score was associated with 28% (95%CI:1.16-1.41; P < 0.001) higher odds of injury. Basic water services compared to surface water was associated with 48% lower odds (OR = 0.52; 95%CI:0.33-0.82; P = 0.005) of injury. Finally, using linear regressions among 332 adults, HWISE scores were not associated with HCC. Past water-related injury was associated with higher HCC (Beta = 0.31; SE = 0.09; P = 0.029) among women, but not men. Relying on unimproved water services compared to surface was associated with 46.2% higher HCC for women (Beta=0.38; SE=0.14; P=0.048) and 55.3% higher HCC for men (Beta=0.44; SE=0.15; P=0.044), respectively. Overall, our findings demonstrate that water insecurity can become embodied through water-related injuries and elevated HCC. Improving water service levels through an equity lens may help ameliorate water insecurity and its accompanying negative health effects., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Water security is a powerful concept that is still in its early days in the field of nutrition. Given the prevalence and severity of water issues and the many interconnections between water and nutrition, we argue that water security deserves attention commensurate with its importance to human nutrition and health. To this end, we first give a brief introduction to water insecurity and discuss its conceptualization in terms of availability, access, use, and stability. We then lay out the empirical grounding for its assessment. Parallels to the food-security literature are drawn throughout, both because the concepts are analogous and food security is familiar to the nutrition community. Specifically, we review the evolution of scales to measure water and food security and compare select characteristics. We then review the burgeoning evidence for the causes and consequences of water insecurity and conclude with 4 recommendations: 1) collect more water-insecurity data (i.e., on prevalence, causes, consequences, and intervention impacts); 2) collect better data on water insecurity (i.e., measure it concurrently with food security and other nutritional indicators, measure intrahousehold variation, and establish baseline indicators of both water and nutrition before interventions are implemented); 3) consider food and water issues jointly in policy and practice (e.g., establish linkages and possibilities for joint interventions, recognize the environmental footprint of nutritional guidelines, strengthen the nutrition sensitivity of water-management practices, and use experience-based scales for improving governance and regulation across food and water systems); and 4) make findings easily available so that they can be used by the media, community organizations, and other scientists for advocacy and in governance (e.g., tracking progress towards development goals and holding implementers accountable). As recognition of the importance of water security grows, we hope that so too will the prioritization of water in nutrition research, funding, and policy., (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society for Nutrition.)

Objectives: This study examined how household food insecurity (HFI) and chronic stress relate to adiposity among Tsimane' hunter-forager-horticulturalists in remote Bolivia with limited access to energy-dense processed foods that promote weight gain among industrialized populations., Methods: Retrospective cross-sectional data on HFI (via the Household Food Insecurity Access Scale [HFIAS]), hair cortisol concentration (HCC), adiposity (BMI, body fat percentage [%BF]), and sociodemographics were collected from 171 men, 164 women, and 167 children. Linear mixed-effects models tested linear, quadratic, joint, and interactive relationships between adiposity measures and both the HFIAS score and HCC., Results: Among children, each 3-point HFIAS score increase was associated with a 0.44-point higher %BF (SE = 0.22, P = 0.04). However, each 20% increase in HCC was associated with a -0.29-point difference in %BF (SE = 0.12, P = 0.01). Among men, a slight curvilinear relationship emerged between HFIAS and BMI. HFIAS and HCC were unrelated to adiposity measures among women. HCC did not modify relationships between HFIAS and adiposity in any subgroup., Conclusions: These findings from a remote, small-scale population suggest that positive associations between HFI and adiposity are not isolated to contexts of industrialized food environments and heavy reliance on processed foods. However, these dynamics and the role of stress appear to differ by sex and age group., (© 2021 The Obesity Society.)

Water salinity is a growing global environmental health concern. However, little is known about the relation between water salinity and chronic health outcomes in non-coastal, lean populations. Daasanach pastoralists living in northern Kenya traditionally rely on milk, yet are experiencing socioecological changes and have expressed concerns about the saltiness of their drinking water. Therefore, this cross-sectional study conducted water quality analyses to examine how water salinity, along with lifestyle factors like milk intake, was associated with hypertension (blood pressure BP ≥140 mm Hg systolic or ≥90 mm Hg diastolic) and hyperdilute urine (urine specific gravity <1.003 g/mL, indicative of altered kidney function). We collected health biomarkers and survey data from 226 non-pregnant adults (46.9% male) aged 18+ from 134 households in 2019 along with participant observations in 2020. The salinity (total concentration of all dissolved salts) of reported drinking water from hand-dug wells in dry river beds, boreholes, and a pond ranged from 120 to 520 mg/L. Water from Lake Turkana and standpipes, which was only periodically used for consumption when no other drinking sources are available, ranged from 1100 to 2300 mg/L. Multiple logistic regression models with standard errors clustered on households indicate that each additional 100 mg/L of drinking water salinity was associated with 45% (95% CI: 1.09-1.93, P = 0.010) increased odds of hypertension and 33% (95% CI: 0.97-1.83, P = 0.075) increased odds of hyperdilute urine adjusted for confounders. Results were robust to multiple specifications of the models and sensitivity analyses. Daily milk consumption was associated with 61-63% (P < 0.01) lower odds of both outcomes. This considerable protective effect of milk intake may be due to the high potassium, magnesium, and calcium contents or the protective lifestyle considerations of moving with livestock. Our study results demonstrate that drinking water salinity may have critical health implications for blood pressure and kidney function even among lean, active pastoralists., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. HJB has consulted for Novo Nordisk on a project unrelated to this one. There are no other conflicts of interest to declare., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In March 2020, the World Health Organization (WHO) issued a set of public guidelines for Coronavirus Disease 2019 (COVID-19) prevention measures that highlighted handwashing, physical distancing, and household cleaning. These health behaviors are severely compromised in parts of the world that lack secure water supplies, particularly in low- and middle-income countries (LMICs). We used empirical data gathered in 2017-2018 from 8,297 households in 29 sites across 23 LMICs to address the potential implications of water insecurity for COVID-19 prevention and response. These data demonstrate how household water insecurity presents many pathways for limiting personal and environmental hygiene, impeding physical distancing and exacerbating existing social and health vulnerabilities that can lead to more severe COVID-19 outcomes. In the four weeks prior to survey implementation, 45.9% of households in our sample either were unable to wash their hands or reported borrowing water from others, which may undermine hygiene and physical distancing. Further, 70.9% of households experienced one or more water-related problems that potentially undermine COVID-19 control strategies or disease treatment, including insufficient water for bathing, laundering, or taking medication; drinking unsafe water; going to sleep thirsty; or having little-to-no drinking water. These findings help identify where water provision is most relevant to managing COVID-19 spread and outcomes., (Copyright © 2021 Elsevier GmbH. All rights reserved.)

We evaluated nucleic acid amplification testing (NAAT) for Zika virus on whole-blood specimens compared with NAAT on serum and urine specimens among asymptomatic pregnant women during the 2015-2016 Puerto Rico Zika outbreak. Using NAAT, more infections were detected in serum and urine than in whole blood specimens.

Self-identified race/ethnicity and socioeconomic status (SES) contribute to disparities in several health domains, although research on their effects on women's reproductive function has largely focused on links between SES and age of menarche. Here, we assessed whether race/ethnicity, SES, and downstream correlates of SES such as food security and health-insurance security are associated with age of menarche, infertility, and live birth ratios (ratios of recognized pregnancies resulting in live births) in the USA. We used cross-sectional data from 1694 women aged 12-18 years for menarche (2007-2016), 974 women aged 23-45 for infertility (2013-2016), and 1714 women aged 23-45 for live birth ratios (2007-2016) from the National Health and Nutrition Examination Survey. We estimated multiple linear and logistic regressions with survey weights to test these associations. When controlling for lifestyle (activity levels, smoking, alcohol consumption) and physiological factors (diabetes, weight status), non-Hispanic (NH) black and Hispanic girls reported a significantly lower age of menarche by about 4.3 (standard error [SE] = 0.08, p < 0.001), and 3.2 months (SE = 0.09, p < 0.001), respectively, relative to NH white girls. NH black women reported live birth ratios 9% (SE = 0.02, p < 0.001) lower than NH white women. Women with unstable health insurance reported live birth ratios 6% (SE = 0.02, p = 0.02) lower than women with stable health insurance. Race/ethnicity, SES, and its downstream correlates were not associated with infertility. One hypothesized explanation for observed disparities in age of menarche and live birth ratios is the embodiment of discrimination faced by NH black women within the USA. Our findings also underscore the importance of health insurance access for favorable reproductive health outcomes. Future work should elucidate the role of embodied discrimination and other downstream correlates of SES in modulating women's reproductive health outcomes to inform strategies to mitigate health disparities.

Objectives: This study compared the prevalence of concentrated urine (urine specific gravity ≥1.021), an indicator of hypohydration, across Tsimane' hunter-forager-horticulturalists living in hot-humid lowland Bolivia and Daasanach agropastoralists living in hot-arid Northern Kenya. It tested the hypotheses that household water and food insecurity would be associated with higher odds of hypohydration., Methods: This study collected spot urine samples and corresponding weather data along with data on household water and food insecurity, demographics, and health characteristics among 266 Tsimane' households (N = 224 men, 235 women, 219 children) and 136 Daasanach households (N = 107 men, 120 women, 102 children)., Results: The prevalence of hypohydration among Tsimane' men (50.0%) and women (54.0%) was substantially higher (P < .001) than for Daasanach men (15.9%) and women (17.5%); the prevalence of hypohydration among Tsimane' (37.0%) and Daasanach (31.4%) children was not significantly different (P = .33). Multiple logistic regression models suggested positive but not statistically significant trends between household water insecurity and odds of hypohydration within populations, yet some significant joint effects of water and food insecurity were observed. Heat index (2°C) was associated with a 23% (95% confidence interval [CI]: 1.09-1.40, P = .001), 34% (95% CI: 1.18-1.53, P < .0005), and 23% (95% CI: 1.04-1.44, P = .01) higher odds of hypohydration among Tsimane' men, women, and children, respectively, and a 48% (95% CI: 1.02-2.15, P = .04) increase in the odds among Daasanach women. Lactation status was also associated with hypohydration among Tsimane' women (odds ratio = 3.35, 95% CI: 1.62-6.95, P = .001)., Conclusion: These results suggest that heat stress and reproductive status may have a greater impact on hydration status than water insecurity across diverse ecological contexts., (© 2020 Wiley Periodicals LLC.)

Understanding factors contributing to variation in 'biological age' is essential to understanding variation in susceptibility to disease and functional decline. One factor that could accelerate biological aging in women is reproduction. Pregnancy is characterized by extensive, energetically-costly changes across numerous physiological systems. These 'costs of reproduction' may accumulate with each pregnancy, accelerating biological aging. Despite evidence for costs of reproduction using molecular and demographic measures, it is unknown whether parity is linked to commonly-used clinical measures of biological aging. We use data collected between 1999 and 2010 from the National Health and Nutrition Examination Survey (n = 4418) to test whether parity (number of live births) predicted four previously-validated composite measures of biological age and system integrity: Levine Method, homeostatic dysregulation, Klemera-Doubal method biological age, and allostatic load. Parity exhibited a U-shaped relationship with accelerated biological aging when controlling for chronological age, lifestyle, health-related, and demographic factors in post-menopausal, but not pre-menopausal, women, with biological age acceleration being lowest among post-menopausal women reporting between three and four live births. Our findings suggest a link between reproductive function and physiological dysregulation, and allude to possible compensatory mechanisms that buffer the effects of reproductive function on physiological dysregulation during a woman's reproductive lifespan. Future work should continue to investigate links between parity, menopausal status, and biological age using targeted physiological measures and longitudinal studies.

Purpose: Risks of dehydration and cognitive decline increase with advancing age, yet the relation between dehydration, water intake, and cognitive performance among older adults remains understudied., Methods: Using data from the 2011-2014 cycles of the Nutrition and Health Examination Survey (NHANES), we tested if calculated serum osmolarity (Sosm) and adequate intake (AI) of water among women (n = 1271) and men (n = 1235) ≥ 60 years old were associated with scores of immediate and delayed recall, verbal fluency, and attention/processing speed. Sosm was categorized as < 285 (hyperhydrated), 285-289, 290-294, 295-300, or > 300 (dehydrated) mmol/L. AI of water was defined as ≥ 2 L/day for women and ≥ 2.5 L/day for men., Results: Women with Sosm between 285 and 289 mmol/L scored 3.2-5.1 points higher on the Digit Symbol Substitution test (DSST) of attention/processing speed than women in other Sosm categories (P values < 0.05). There was evidence of a curvilinear relationship between DSST scores and Sosm among women and men (P values for quadratic terms < 0.02). Meeting an alternative AI on water intake of ≥ 1 mL/kcal and ≥ 1500 mL, but not the sex-specific AI, was associated with scoring one point higher on a verbal fluency test (P = 0.02) and two points higher on the DSST (P = 0.03) among women. Significant negative associations between dehydration or inadequate water intake and test scores were not observed among men., Conclusion: Hydration status and water intake were moderately associated with attention/processing speed among females. Future work should consider the effects of both dehydration and overhydration on cognitive function and investigate potential sex differences in cognitive responses to hydration status.

Water problems due to scarcity, inaccessibility, or poor quality are a major barrier to household functioning, livelihood, and health globally. Household-to-household water borrowing has been posited as a strategy to alleviate unmet water needs. However, the prevalence and predictors of this practice have not been systematically examined. Therefore, we tested whether water borrowing occurs across diverse global contexts with varying water problems. Second, we tested if household water borrowing is associated with unmet water needs, perceived socio-economic status (SES), and/or water-related system failures, and if water access moderated (or changed) these relationships. Using survey data from the Household Water Insecurity Experiences (HWISE) study from 21 sites in 19 low- and middle-income countries (n = 5495 households), we found that household-to-household water borrowing was practiced in all 21 sites, with 44.7% (11.4-85.4%) of households borrowing water at least once the previous month. Multilevel mixed-effect logistic regression models demonstrate that high unmet water needs (odds ratio [OR] = 2.86], 95% confidence interval [CI] = 2.09-3.91), low perceived SES (OR = 1.09; 95% CI = 1.05-1.13), and water-related system failures (23-258%) were all significantly associated with higher odds of water borrowing. Significant interactions (all p < 0.01) between water access, unmet water needs, and water-related system failures on water borrowing indicate that water access moderates these relationships. These data are the first to demonstrate that borrowing water is commonly used by households around the world to cope with water insecurity. Due to how prevalent water borrowing is, its implications for social dynamics, resource allocation, and health and well-being are likely vast but severely under-recognized., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Billions of people globally, living with various degrees of water insecurity, obtain their household and drinking water from diverse sources that can absorb a disproportionate amount of a household's income. In theory, there are income and expenditure thresholds associated with effective mitigation of household water insecurity, but there is little empirical research about these mechanisms and thresholds in low- and middle-income settings. This study used data from 3655 households from 23 water-insecure sites in 20 countries to explore the relationship between cash water expenditures (measured as a Z-score, percent of income, and Z-score of percent of income) and a household water insecurity score, and whether income moderated that relationship. We also assessed whether water expenditures moderated the relationships between water insecurity and both food insecurity and perceived stress. Using tobit mixed effects regression models, we observed a positive association between multiple measures of water expenditures and a household water insecurity score, controlling for demographic characteristics and accounting for clustering within neighborhoods and study sites. The positive relationships between water expenditures and water insecurity persisted even when adjusted for income, while income was independently negatively associated with water insecurity. Water expenditures were also positively associated with food insecurity and perceived stress. These results underscore the complex relationships between water insecurity, food insecurity, and perceived stress and suggest that water infrastructure interventions that increase water costs to households without anti-poverty and income generation interventions will likely exacerbate experiences of household water insecurity, especially for the lowest-income households., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Increases in reproductive hormones like estrogen, play an important role in the remarkable increases in plasma volume observed in pregnancy. Accurate estimates of plasma volume expansion during pregnancy depend on correctly timing and measuring plasma volume in nonpregnant women. However, to date, there is no consensus on the pattern of plasma volume across the menstrual cycle. We prospectively measured plasma volume in 45 women across a single menstrual cycle. A urine-based fertility monitor was used to time three clinic visits to distinct points in the menstrual cycle: the early follicular phase (~day 2), periovulation (~day 12), and the mid-point of the luteal phase (~day 21)-based on a 28-day cycle length. Healthy women aged 18-41 years with regular menstrual cycles and a healthy body weight were enrolled in the study. At each visit, blood samples were collected before and after injection of 0.25 mg/kg body weight of indocyanine green dye (ICG). Pre- and post-ICG injection plasma samples were used to measure plasma volume. Preinjection samples were used to measure ovarian hormones and plasma osmolality. Mean plasma volume was highest during the early follicular phase (2,276 ± 478 ml); it declined to 2,232 ± 509 ml by the late follicular phase and to 2,228 ± 502 ml by the midluteal phase. This study found that overall variations in plasma volume are small across the menstrual cycle. Therefore, in clinical practice and research, the menstrual cycle phase may not be an important consideration when evaluating plasma volume among women of reproductive age., (© 2020 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.)

Body water homeostasis is critical for optimal physiological and cognitive function for humans. The majority of research has illustrated the negative biological consequences of failing to meet water needs. The human body has several mechanisms for detecting, regulating, and correcting body water deficits and excesses. However, variation exists in total water intake and how people meet those water needs as well as thirst thresholds and how well people tolerate water restriction. An evolutionary and developmental framework provides an underexplored perspective into human water needs by examining how adaptations, early life experiences and environments, as well as life course changes in health states and behaviors may shape these critical factors in body water homeostasis. This article first reviews biological and behavioral adaptations to water scarcity among animals and humans. It then examines human variation in water intake in a mostly water secure environment through the analysis of National Health and Nutrition Examination Survey dietary data and the link between water intake patterns and hydration biomarkers. Next, it reviews existing evidence of how maternal water restriction in utero and during lactation shape vasopressin release, thirst thresholds, drinking patterns, and body water homeostasis for the infant. Early life water restriction appears to have implications for hydration status, body size, and cardiovascular health. Finally, it examines how life course changes in health states and behaviors, including obesity, sleep, and parasitic infection, affect body water homeostasis. This article poses new questions about the plasticity and shaping of human water needs, thirst, and hydration behaviors., (© 2019 Wiley Periodicals, Inc.)

Water connects the environment, culture, and biology, yet only recently has it emerged as a major focus for research in human biology. To facilitate such research, we describe methods to measure biological, environmental, and perceptual indicators of human water needs. This toolkit provides an overview of methods for assessing different dimensions of human water need, both well-established and newly-developed. These include: (a) markers of hydration (eg, urine specific gravity, doubly labeled water) important for measuring the impacts of water need on human biological functioning; (b) methods for measuring water quality (eg, digital colorimeter, membrane filtration) essential for understanding the health risks associated with exposure to microbiological, organic, metal, inorganic nonmental, and other contaminants; and (c) assessments of household water insecurity status that track aspects of unmet water needs (eg, inadequate water service, unaffordability, and experiences of water insecurity) that are directly relevant to human health and biology. Together, these methods can advance new research about the role of water in human biology and health, including the ways that insufficient, unsafe, or insecure water produces negative biological and health outcomes., (© 2019 The Authors. American Journal of Human Biology published by Wiley Periodicals, Inc.)

Objective: This study examined changes in body fat and diet among Tsimane' forager-horticulturalists and assessed how dietary shifts relate to increases in adiposity between 2002 and 2010., Methods: Longitudinal anthropometric and household-level dietary recall data from 365 men and 339 women aged ≥20 years in the Tsimane' Amazonian Panel Study were used. Multilevel mixed-effects models estimated how BMI, body fat percentage, waist circumference, skinfolds, and fat-free mass relate to household consumption of crops, hunted or fished foods, domesticated animal products, cooking oil, and refined grains and sugar., Results: Women's prevalence of overweight and obesity increased from 22.6% and 2.4% in 2002 to 28.8% and 8.9% in 2010, respectively, and BMI increased by 0.60% ± 0.12% per year (P < 0.001). Increases in fat-free mass accounted for some of this observed weight gain among women. Men's prevalence of overweight and obesity increased from 16.2% and 0.7% to 25.0% and 2.2%, respectively, and BMI increased by 0.22% ± 0.09% per year (P = 0.009). Household use of cooking oil increased and was positively associated with female BMI. Consumption of domesticated animal products did not change significantly but was positively associated with female BMI and male waist circumference., Conclusions: Even small increases in energy-dense market-based foods can contribute to adiposity gains among a moderately active, subsistence-based population., (© 2019 The Obesity Society.)

Water insecurity massively undermines health, especially among impoverished and marginalized communities. Emerging evidence shows that household-to-household water sharing is a widespread coping strategy in vulnerable communities. Sharing can buffer households from the deleterious health effects that typically accompany seasonal shortages, interruptions of water services and natural disasters. Conversely, sharing may also increase exposure to pathogens and become burdensome and distressing in times of heightened need. These water sharing systems have been almost invisible within global health research but need to be explored, because they can both support and undermine global public health interventions, planning and policy., (© The Author(s) 2018. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Despite a growing number of publicly available datasets, the use of these datasets for secondary analyses in human biology is less common compared with other fields. Secondary analysis of existing data offers an opportunity for human biologists to ask unique questions through an evolutionary and biocultural lens, allowing for an analysis of cultural and structural nuances that affect health. Leveraging publicly available datasets for human biology research is a way for students and established researchers to complement their data collection, use existing data for master's and doctoral theses, pilot test questions, and use existing data to answer interesting new questions or explore questions at the population level. Here we describe where publicly available data are stored, highlighting some data repositories and how to access them. We then discuss how to decide which dataset is right, depending on the research question. Next, we describe steps to construct datasets, analytical considerations and methodological challenges, best practices, and limitations depending on the structure of the study. We close by highlighting a number of publicly available datasets that have been used by human biologists and other datasets that may be of interest to the community, including research that has been conducted on some example datasets., (© 2019 Wiley Periodicals, Inc.)

Objectives: Evidence from industrialized populations suggests that urine concentrating ability declines with age. However, lifestyle factors including episodic protein intake and low hypertension may help explain differences between populations. Whether this age-related decline occurs among small-scale populations with active lifestyles and non-Western diets is unknown. We test the universality of age-related urine concentration decline., Materials and Methods: We used urine specific gravity (Usg) and urine osmolality (Uosm) data from 15,055 U.S. nonpregnant adults without kidney failure aged 18-80 in 2007-2012 participating in the National Health and Nutrition Examination Survey (NHANES). We tested the relationship of age on urine concentration biomarkers with multiple linear regressions using survey commands. We compared results to longitudinal data on Usg from 116 Tsimane' forager-horticulturalists (266 observations) adults aged 18-83 in 2013-2014 from Lowland Bolivia, and to 38 Hadza hunter-gatherers (156 observations) aged 18-75 in 2010-2015 from Tanzania using random-effects panel linear regressions., Results: Among U.S. adults, age was significantly negatively associated with Usg (Adjusted beta [B] = -0.0009 g/mL/10 years; SE = 0.0001; p < 0.001) and Uosm (B = -28.1 mOsm/kg/10 yr; SE = 2.4; p < 0.001). In contrast, among Tsimane' (B = 0.0003 g/mL/10 yr; SE = 0.0002; p = 0.16) and Hadza (B = -0.0004 g/mL/10 yr; SE = 0.0004; p = 0.29) age was not associated with Usg. Older Tsimane' and Hadza exhibited similar within-individual variability in Usg equivalent to younger adults., Discussion: While U.S. adults exhibited age-related declines in urine concentration, Tsimane' and Hadza adults did not exhibit the same statistical decline in Usg. Mismatches between evolved physiology and modern environments in lifestyle may affect kidney physiology and disease risk., (© 2019 Wiley Periodicals, Inc.)

Study Objectives: Short and long sleep durations are linked to reduced kidney function, but little research has examined how sleep is associated with hydration status. Our aim was to assess the relationship between sleep duration and urinary hydration biomarkers among adults in a cross-cultural context., Methods: Three samples of adults aged ≥20 years were analyzed: 2007-2008 National Health and Nutrition Examination Survey (NHANES; n = 4680), 2009-2012 NHANES (n = 9559), and 2012 cross-sectional wave of the Chinese Kailuan Study (n = 11903), excluding pregnant women and adults with failing kidneys. We estimated multiple linear regression models between self-reported usual night-time sleep duration (<6, 6, 7, 8 (reference), and ≥9 hr/day) and urine specific gravity (Usg) and urine osmolality (Uosm) as continuous variables and logistic regression models dichotomized as inadequate hydration (>1.020 g/mL; >831 mOsm/kg). In primary analyses, we estimated models excluding diabetes and diuretic medications for healthier subpopulations (NHANES, n = 11353; Kailuan, n = 8766)., Results: In the healthier NHANES subset, 6 hr was associated with significantly higher Usg and odds of inadequate hydration (adjusted OR: 1.59, 95% CI: 1.25, 2.03) compared with 8 hr. Regression results were mixed using Uosm, but in the same direction as Usg. Among Chinese adults, short sleep duration (<6 and 6 hr) was associated with Usg and higher likelihood of inadequate hydration (6 hr adjusted OR: 1.42, 95% CI: 1.26, 1.60). No consistent association was found with sleeping ≥9 hr., Conclusions: Short sleep duration was associated with higher odds of inadequate hydration in US and Chinese adults relative to sleeping 8 hr.

Objectives: Schistosome infections can damage organs important for water homeostasis, especially the kidneys. Urogenital schistosomiasis (caused by Schistosoma haematobium) increases protein and blood in urine and intestinal schistosomiasis (caused by S. mansoni) affects total body water. However, no data exist on how different schistosome species affect urine specific gravity (USG), a hydration biomarker. Therefore, we assessed the relationship between S. haematobium- and S. mansoni-infected and uninfected women and USG in rural Tanzania., Materials and Methods: Surveys were conducted and stool and urine samples were collected among 211 nonpregnant women aged 18-50. S. haematobium eggs were detected using the urine filtration method. S. mansoni eggs were detected using the Kato Katz method. USG was measured using a refractometer and analyzed as both a continuous and dichotomous variable. Regression (linear/logistic) models were estimated to test the relationship between infection and hydration status., Results: The prevalence of S. haematobium was 5.9% and S. mansoni was 5.4% with no coinfections. In regression models, S. haematobium-infected women had significantly higher USG (Beta = 0.007 g mL -1 ; standard error = 0.002; p = 0.001) and odds (Odds ratio: 7.76, 95% CI: 1.21-49.5) of elevated USG (>1.020 g mL -1 ) than uninfected women, whereas S. mansoni-infected women did not., Discussion: Schistosoma haematobium, but not S. mansoni, infection is associated with higher USG and risk of inadequate hydration. Future work should determine whether findings are attributable to parasite-induced debris in urine or urinary tract pathologies and signs of renal damage. Human and non-human primate studies using USG in schistosome-endemic areas should account for schistosomiasis., (© 2018 Wiley Periodicals, Inc.)

Objective: Differences in bottled v. tap water intake may provide insights into health disparities, like risk of dental caries and inadequate hydration. We examined differences in plain, tap and bottled water consumption among US adults by sociodemographic characteristics., Design: Cross-sectional analysis. We used 24 h dietary recall data to test differences in percentage consuming the water sources and mean intake between groups using Wald tests and multiple logistic and linear regression models., Setting: National Health and Nutrition Examination Survey (NHANES), 2007-2014., Subjects: A nationally representative sample of 20 676 adults aged ≥20 years., Results: In 2011-2014, 81·4 (se 0·6) % of adults drank plain water (sum of tap and bottled), 55·2 (se 1·4) % drank tap water and 33·4 (se 1·4) % drank bottled water on a given day. Adjusting for covariates, non-Hispanic (NH) Black and Hispanic adults had 0·44 (95 % CI 0·37, 0·53) and 0·55 (95 % CI 0·45, 0·66) times the odds of consuming tap water, and consumed B=-330 (se 45) ml and B=-180 (se 45) ml less tap water than NH White adults, respectively. NH Black, Hispanic and adults born outside the fifty US states or Washington, DC had 2·20 (95 % CI 1·79, 2·69), 2·37 (95 % CI 1·91, 2·94) and 1·46 (95 % CI 1·19, 1·79) times the odds of consuming bottled water than their NH White and US-born counterparts. In 2007-2010, water filtration was associated with higher odds of drinking plain and tap water., Conclusions: While most US adults consumed plain water, the source (i.e. tap or bottled) and amount differed by race/Hispanic origin, nativity status and education. Water filters may increase tap water consumption.

While 884 million people worldwide lack access to clean water, millions live in flood-prone regions. Unexpected flooding increases risk of diarrheal diseases and is expected to occur with increased frequency in the 21st century. Water insecurity is linked to mental distress in water scarce regions, yet this construct has not been examined closely among populations living in flood-prone regions. This paper examines how differences in water sources and lifestyle among Tsimane' forager-horticulturalists in lowland Bolivia are related to water insecurity after a historic flood in 2014, and in turn, how water insecurity is associated with diarrhea and dehydration. Pre-flood data come from qualitative interviews with 36 household heads, anthropometrics, participant observation, and water quality analysis between September 2013-January 2014 used to create a locally-adapted water insecurity questionnaire. Water insecurity was measured after the historic flood; no pre-flood water insecurity measures are available. Post-flood data were collected through surveys, water quality analysis, and health exams using near-exhaustive sampling in two villages, yielding 118 adults and 115 children (aged 2-12 years) in 62 households between March-April 2014. Overall, 89% of adults reported medium or high water insecurity. Only hand-pumps tested negative for pathogenic bacteria both pre- and post-flood. Tobit regressions suggest that hand-pumps (when available) and adult age were associated with lower water insecurity scores. Multiple logistic regressions suggest that adults with high water insecurity were more likely to report diarrhea than adults with low (Odds Ratio [OR] 9.2; 95% CI: 1.27-67.1). Children from households with medium (OR: 6.8; 95% CI: 1.41-32.5) or high (OR: 14.0; 95% CI: 2.40-81.5) water insecurity had significantly higher odds of dehydration than children in households with low water insecurity. Catastrophic flooding may systematically increase dimensions of household water insecurity. This research suggests an experience-based measure of water insecurity is associated with objective health outcomes., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Adequate water intake is critical to physiologic and cognitive functioning. Although water requirements increase with body size, it remains unclear whether weight status modifies the relation between water intake and hydration status., Objective: We examined how the association between water intake and urine osmolality, which is a hydration biomarker, varied by weight status., Design: NHANES cross-sectional data (2009-2012) were analyzed in 9601 nonpregnant adults aged ≥20 y who did not have kidney failure. Weight status was categorized with the use of body mass index on the basis of measured height and weight (underweight or normal weight, overweight, and obesity). Urine osmolality was determined with the use of freezing-point depression osmometry. Hypohydration was classified according to the following age-dependent formula: ≥831 mOsm/kg - [3.4 × (age - 20 y)]. Total water intake was determined with the use of a 24-h dietary recall and was dichotomized as adequate or low on the basis of the Institute of Medicine's adequate intake recommendations for men and women (men: ≥3.7 or <3.7 L; nonlactating women: ≥2.7 or <2.7 L; lactating women: ≥3.8 or <3.8 L for adequate or low intakes, respectively). We tested interactions and conducted linear and log-binomial regressions., Results: Total water intake (P = 0.002), urine osmolality (P < 0.001), and hypohydration prevalence (P < 0.001) all increased with higher weight status. Interactions between weight status and water intake status were significant in linear (P = 0.005) and log-binomial (P = 0.015) models, which were then stratified. The prevalence ratio of hypohydration between subjects with adequate water intake and those with low water intake was 0.56 (95% CI: 0.43, 0.73) in adults who were underweight or normal weight, 0.67 (95% CI: 0.57, 0.79) in adults who were overweight, and 0.78 (95% CI: 0.70, 0.88) in adults who were obese., Conclusion: On a population level, obesity modifies the association between water intake and hydration status., (© 2016 American Society for Nutrition.)