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Potassium supplementation has been associated with reduced urinary calcium (Ca) excretion and increased Ca balance. Dietary interventions assessing the impact of potassium on bone are lacking. In this secondary analysis of a study designed primarily to determine blood pressure effects, we assessed the effects of potassium intake from potato sources and a potassium supplement on urinary Ca, urine pH, and Ca balance. Thirty men (n = 15) and women (n = 15) with a mean ± SD age and BMI of 48.2 ± 15 years and 31.4 ± 6.1 kg/m2, respectively, were enrolled in a cross-over, randomized control feeding trial. Participants were assigned to a random order of four 16-day dietary potassium interventions including a basal diet (control) of 2300 mg/day (~60 mmol/day) of potassium, and three phases of an additional 1000 mg/day (3300 mg/day(~85 mmol/day) total) of potassium in the form of potatoes (baked, boiled, or pan-heated), French fries (FF), or a potassium (K)-gluconate supplement. Calcium intake for all diets was approximately 700–800 mg/day. Using a mixed model ANOVA there was a significantly lower urinary Ca excretion in the K-gluconate phase (96 ± 10 mg/day) compared to the control (115 ± 10 mg/day; p = 0.027) and potato (114 ± 10 mg/day; p = 0.033). In addition, there was a significant difference in urinary pH between the supplement and control phases (6.54 ± 0.16 vs. 6.08 ± 0.18; p = 0.0036). There were no significant differences in Ca retention. An increased potassium intake via K-gluconate supplementation may favorably influence urinary Ca excretion and urine pH. This trial was registered at ClinicalTrials.gov as NCT02697708.

Increased potassium intake has been linked to improvements in cardiovascular and other health outcomes. We assessed increasing potassium intake through food or supplements as part of a controlled diet on blood pressure (BP), microcirculation (endothelial function), and potassium and sodium retention in thirty pre-hypertensive-to-hypertensive men and women. Participants were randomly assigned to a sequence of four 17 day dietary potassium treatments: a basal diet (control) of 60 mmol/d and three phases of 85 mmol/d added as potatoes, French fries, or a potassium gluconate supplement. Blood pressure was measured by manual auscultation, cutaneous microvascular and endothelial function by thermal hyperemia, utilizing laser Doppler flowmetry, and mineral retention by metabolic balance. There were no significant differences among treatments for end-of-treatment BP, change in BP over time, or endothelial function using a mixed-model ANOVA. However, there was a greater change in systolic blood pressure (SBP) over time by feeding baked/boiled potatoes compared with control (−6.0 mmHg vs. −2.6 mmHg, p = 0.011) using contrast analysis. Potassium retention was highest with supplements. Individuals with a higher cardiometabolic risk may benefit by increasing potassium intake. This trial was registered at ClinicalTrials.gov as NCT02697708.

There are limited data on phosphorus balance and the effect of dietary calcium supplements on phosphorus balance in adolescents. The purpose of this study was to determine phosphorus balance and the effect of increasing dietary calcium intake with a supplement on net phosphorus absorption and balance in healthy adolescent girls. This study utilized stored urine, fecal, and diet samples from a previously conducted study that focused on calcium balance. Eleven healthy girls ages 11 to 14 years participated in a randomized crossover study, which consisted of two 3-week periods of a controlled diet with low (817 ± 19.5 mg/d) or high (1418 ± 11.1 mg/d) calcium, separated by a 1-week washout period. Phosphorus intake was controlled at the same level during both placebo and calcium supplementation (1435 ± 23.5 and 1453 ± 28.0 mg/d, respectively, p = 0.611). Mean phosphorus balance was positive by about 200 mg/d and was unaffected by the calcium supplement (p = 0.826). Urinary phosphorus excretion was lower with the calcium supplement (535 ± 42 versus 649 ± 41 mg/d, p = 0.013), but fecal phosphorus and net phosphorus absorption were not significantly different between placebo and calcium supplement (553 ± 60 versus 678 ± 63 versus mg/d, p = 0.143; 876 ± 62 versus 774 ± 64 mg/d, p = 0.231, respectively). Dietary phosphorus underestimates using a nutrient database compared with the content measured chemically from meal composites by ~40%. These results show that phosphorus balance is positive in girls during adolescent growth and that a calcium dietary supplement to near the current recommended level does not affect phosphorus balance when phosphorus intake is at 1400 mg/d, a typical US intake level.

IGF-I is a pivotal hormone in pediatric musculoskeletal development. Although recent data suggest that the role of IGF-I in total body lean mass and total body bone mass accrual may be compromised in children with insulin resistance, cortical bone geometric outcomes have not been studied in this context. Therefore, we explored the influence of insulin resistance on the relationship between IGF-I and cortical bone in children. A secondary aim was to examine the influence of insulin resistance on the lean mass-dependent relationship between IGF-I and cortical bone. Children were otherwise healthy, early adolescent black and white boys and girls (ages 9 to 13 years) and were classified as having high (n = 147) or normal (n = 168) insulin resistance based on the homeostasis model assessment of insulin resistance (HOMA-IR). Cortical bone at the tibia diaphysis (66% site) and total body fat-free soft tissue mass (FFST) were measured by peripheral quantitative computed tomography (pQCT) and dual-energy X-ray absorptiometry (DXA), respectively. IGF-I, insulin, and glucose were measured in fasting sera and HOMA-IR was calculated. Children with high HOMA-IR had greater unadjusted IGF-I (p

Potassium is an essential nutrient of concern according to recent Dietary Guidelines for Americans Advisory Committees, with less than 3% of the population meeting the current adequate intake (AI) level of 4700mg/d. Increases in potassium intake have been linked to improvements in cardiovascular and other metabolic health outcomes. Blood pressure (BP) is currently the primary criterion for determining potassium requirements. In this clinical trial, we assessed the effects of increasing potassium intake on BP and microcirculation (endothelial function). Thirty pre-hypertensive-to-hypertensive (Systolic BP ≥ 120mmHg) men (N=15) and Women (N=15) with a mean ± SD age, BMI, and BP (systolic(SBP)/ diastolic(DBP)) of 48.2 ± 15 y, 31.4 ± 6.1, and 136.3 ± 11.9/ 86.1 ± 7.1 mmHg, respectively, were enrolled in a cross-over randomized control diet trial. Participants were assigned to a random order of four 16-day dietary potassium interventions including a basal diet (control) of 2300mg/d(~60mmol/d), and three periods of an additional 1000mg/d(3300mg/d(~85mmol/d) total) of potassium in the form of potatoes (baked, boiled, or pan-heated with no additional fat), French fries, or a potassium gluconate supplement. Each intervention period was separated by two or more weeks of wash out. Blood pressure was measured in triplicate using manual auscultation on days 1, 4, 6, 8, 11, 13, 15, 16, and 17 of each intervention. Microvascular and endothelial function were assessed via thermal hyperemia, utilizing laser Doppler flowmetry (LDF), at baseline and at the end of each intervention. Results for differences in both SBP and DBP ± SE were assessed at the end treatment (average of day 15, 16, and 17 measurements) using a mixed model with repeated measures and Dunnett adjustment (P < 0.05), with no significant differences among groups (control: 128.7 ± 2.1/ 83.6 ± 1.6, French fries: 127.7 ± 2.2/ 83.7 ± 1.6, potatoes: 127.6 ± 2.3/ 85.1 ± 1.6, supplement: 128.0 ± 2.2/ 83.7 ± 1.7). Utilizing the same statistical analysis, there were also no significant differences in endothelial function (measured as percent of cutaneous vascular conductance max (%CVCmax) ± SE) among groups (control: 87.4 ± 1.5%, French Fries: 87.7 ± 1.4%, potatoes: 88.3 ± 1.1%, supplement: 88.9 ± 1.0%). In this small, controlled feeding study of short duration, increased potassium from potatoes or supplement achieved 70% of recommended intakes, but had no significant benefit to blood pressure or microvascular function in men and women with higher cardiometabolic risk.

Introduction: Hypertension is a major risk factor for CVD affecting 34% of American adults. High sodium (Na) intake is identified as a modifiable risk factor for high blood pressure, but our ability to assess Na intake is poor. The gold standard is to measure Na excretion in a 24h urine collection, but this is burdensome. An alternative method is to predict 24h Na excretion from a spot urine sample. However, we do not know how well predicted 24h Na excretion reflects intake, the true outcome of interest, or the ideal time to collect a spot urine sample. These gaps can only be filled using a controlled feeding study in which intake is known and timing of urine collections is controlled. Hypothesis: We hypothesized that, with currently available equations, 24h Na excretion predicted from spot urine samples will not accurately reflect intake. Methods: This is a secondary analysis of a randomized, multi-phase, crossover, full-feeding trial in healthy adults ( n = 39, aged 29.7 ± 11.2 y). Data from the two control phases were used in which dietary intake and testing conditions were identical. Participants ate three meals in a clinic setting and spot urine samples were collected every 2 hours as part of a 24h collection. Urine samples were analyzed for sodium, potassium, and creatinine. The INTERSALT equations were used to predict 24h Na excretion from each of the 9 spot urine samples collected. Predicted 24h Na excretion values were compared with observed 24h excretion and known dietary intake using repeated measures ANOVA. Intra-class correlations for each timed spot urine sample were calculated to determine the variability in average spot urine Na excretion between the two control phases. Results: Predicted 24h Na excretion using the spot urines at hour 10, 12, overnight, and early morning collection were not significantly different from observed 24h Na excretion (all p ≥ 0.21). However, predicted 24h Na excretion underestimates observed 24h Na excretion by about >600 mg. Importantly, all predicted 24h excretions as well as observed 24h excretion were significantly lower than intake by >1000 mg (all p < 0.001). Intraclass correlations were significant at hour 0, 2, 8, 12, and evening/overnight (all p < 0.05), suggesting low day-to-day variability in Na excretion at these times. Conclusions: Regardless of time of spot urine collection, predicted 24h Na excretion is lower than Na intake, suggesting currently-available equations do not provide adequate estimates of Na intake. The next step is to develop equations to accurately predict Na intake from a controlled feeding study model using spot urine samples collected at a time when Na excretion is consistent from day to day. These improved equations could be used to implement effective dietary interventions to reduce blood pressure and CVD risk.

The rare, long-lived radiotracer, 41Ca, measured by accelerator mass spectrometry in the urine or serum following incorporation into the bone provides an ultra-sensitive tool to assess changes in bone calcium balance in response to an intervention. Changes in bone balance can be followed for years with one small dose that is both radiologically and biologically non-invasive. Sequential interventions can be compared, with greater precision than they can with biochemical markers of bone turnover and with greater power than with bone densitometry. This method is especially useful to screen interventions over a period of weeks. The development and validation of this tool and its applications are reviewed. Mini abstract: Use of 41Ca measured in the urine or blood by accelerator mass spectrometry to assess bone balance provides a tool to compare the relative efficacy of multiple interventions. This perspective provides insights in the use of this novel method and comparisons with more traditional methods for evaluating the efficacy of interventions.

BACKGROUND: Soluble corn fiber (SCF; 12 g fiber/d) is shown to increase calcium absorption efficiency, associated with shifts in the gut microbiota in adolescent males and females who participated in a controlled feeding study. OBJECTIVE: We evaluated the dose response of 0, 10, and 20 g fiber/d delivered by PROMITOR SCF 85 (85% fiber) on calcium absorption, biochemical bone properties, and the fecal microbiome in free-living adolescents. METHODS: Healthy adolescent females (n = 28; aged 11-14 y) randomly assigned into a 3-phase, double-blind, crossover study consumed SCF for 4 wk at each dose (0, 10, and 20 g fiber/d from SCF) alongside their habitual diet and were followed by 3-d clinical visits and 3-wk washout periods. Stable isotope ((44)Ca and (43)Ca) enrichment in pooled urine was measured by inductively coupled plasma mass spectrometry. Fecal microbial community composition was assessed by high-throughput sequencing (Illumina) of polymerase chain reaction-amplified 16S rRNA genes. Mixed model ANOVA and Friedman analysis were used to determine effects of SCF on calcium absorption and to compare mean microbial proportions, respectively. RESULTS: Calcium absorption increased significantly with 10 (13.3% ± 5.3%; P = 0.042) and 20 g fiber/d (12.9% ± 3.6%; P = 0.026) from SCF relative to control. Significant differences in fecal microbial community diversity were found after consuming SCF (operational taxonomic unit measures of 601.4 ± 83.5, 634.5 ± 83.8, and 649.6 ± 75.5 for 0, 10, and 20 g fiber/d, respectively; P < 0.05). Proportions of the genus Parabacteroides significantly increased with SCF dose (1.1% ± 0.8%, 2.1% ± 1.6%, and 3.0% ± 2.0% for 0, 10, and 20 g fiber/d from SCF, respectively; P < 0.05). Increases in calcium absorption positively correlated with increases in Clostridium (r = 0.44, P = 0.023) and unclassified Clostridiaceae (r = 0.40, P = 0.040). CONCLUSIONS: SCF, a nondigestible carbohydrate, increased calcium absorption in free-living adolescent females. Two groups of bacteria may be involved, one directly fermenting SCF and the second fermenting SCF metabolites further, thereby promoting increased calcium absorption. This trial was registered at clinicaltrials.gov as NCT01660503.

Context: Citrus fruits contain unique flavanones. One of the most abundant of the flavanones, hesperidin, has been shown to prevent bone loss in ovariectomized rats. Objective: The objective of the study was to measure the effect of hesperidin with or without calcium supplementation on bone calcium retention in postmenopausal women. Design: The study was a double-blind, placebo-controlled, randomized-order crossover design of 500 g hesperidin with or without 500 mg calcium supplement in 12 healthy postmenopausal women. Bone calcium retention was determined from urinary excretion of the rare isotope, 41Ca, from bone. Results: Calcium plus hesperidin, but not hesperidin alone, improved bone calcium retention by 5.5% (P < .04). Conclusion: Calcium supplementation (Calcilock), in combination with hesperidin, is effective at preserving bone in postmenopausal women.

OBJECTIVES: Preclinical studies suggest that blueberry consumption is associated with improved bone health. This study quantified changes in urinary excretion of the long-lived calcium radioisotope (41)Ca to assess the dose-response effect of blueberries on bone loss in postmenopausal women. We hypothesized that blueberry consumption would reduce bone loss in a dose-dependent manner. METHODS: Healthy women at least 4 years past menopause were dosed with 50 nCi of (41)Ca and completed a 5-mo equilibration period for (41)Ca deposition in bone followed by a 6-wk control period. Subsequently, participants were assigned to a random sequence of 3 intervention periods, each corresponding to a low (17.5 g/d), medium (35 g/d), or high (70 g/d) dose of freeze-dried blueberry powder equivalent to 0.75, 1.5, or 3 cups of fresh blueberries. The blueberry powder was incorporated into granola bars, spread, and drinks consumed daily for 6 wk, followed by a 6-wk washout period. Urinary (41)Ca: Ca ratio was measured by accelerator mass spectrometry in 24-h urine collected weekly during intervention and every 3 wk during washout. Serum 25-hydroxyvitamin D and calcium concentrations were assessed prior to each intervention. Serum bone resorption biomarkers and urinary polyphenols were measured at the end of each control and intervention period. Data were analyzed using a linear mixed model and repeated measures ANOVA. RESULTS: Fourteen healthy, non-osteoporotic (mean bone mineral density t-score: −1.33) women completed the study. Net bone calcium retention increased by 6% in the low (P

There are limited data on phosphorus balance and the effect of dietary calcium supplements on phosphorus balance in adolescents. The purpose of this study was to determine phosphorus balance and the effect of increasing dietary calcium intake with a supplement on net phosphorus absorption and balance in healthy adolescent girls. This study utilized stored urine, fecal, and diet samples from a previously conducted study that focused on calcium balance. Eleven healthy girls ages 11 to 14 years participated in a randomized crossover study, which consisted of two 3-week periods of a controlled diet with low (817 ± 19.5 mg/d) or high (1418 ± 11.1 mg/d) calcium, separated by a 1-week washout period. Phosphorus intake was controlled at the same level during both placebo and calcium supplementation (1435 ± 23.5 and 1453 ± 28.0 mg/d, respectively, p = 0.611). Mean phosphorus balance was positive by about 200 mg/d and was unaffected by the calcium supplement (p = 0.826). Urinary phosphorus excretion was lower with the calcium supplement (535 ± 42 versus 649 ± 41 mg/d, p = 0.013), but fecal phosphorus and net phosphorus absorption were not significantly different between placebo and calcium supplement (553 ± 60 versus 678 ± 63 versus mg/d, p = 0.143; 876 ± 62 versus 774 ± 64 mg/d, p = 0.231, respectively). Dietary phosphorus underestimates using a nutrient database compared with the content measured chemically from meal composites by ~40%. These results show that phosphorus balance is positive in girls during adolescent growth and that a calcium dietary supplement to near the current recommended level does not affect phosphorus balance when phosphorus intake is at 1400 mg/d, a typical US intake level. © 2017 American Society for Bone and Mineral Research.

ContextInsulin resistance is an adverse health outcome that accompanies obesity. Fat mass is negatively associated with the bone mass after adjustment for confounders. Insulin resistance might be an intermediary in this relationship.ObjectiveTo determine whether insulin resistance is an intermediary in the relationship between adiposity and bone mass in adolescents.DesignCross-sectional secondary analysis of baseline data from a previous randomized trial.SettingUniversity research facility.ParticipantsA total of 240 adolescents (68% female), aged 7 to 15 years.Main Outcome MeasuresUsing dual energy x-ray absorptiometry, bone mineral content (BMC), areal bone mineral density, lean mass, and fat mass were measured. Skeletal sites of interest included the total body and lumbar spine (LS). Waist circumference was measured using an anthropometric tape measure. Insulin and glucose were measured in fasting sera, and the homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Path analysis was performed to determine whether the relationship between adiposity and bone was mediated through insulin resistance.ResultsFat mass (r = 0.467; P < 0.001) and waist circumference (r = 0.487; P < 0.001) correlated positively with HOMA-IR. Controlling for race, sex, maturation, lean mass, and height, fat mass, waist circumference, and HOMA-IR were negatively associated with LS BMC and total body areal bone mineral density (P < 0.05 for all). Additionally, path models for fat mass (95% CI, −5.893 to −0.956) and waist circumference (95% CI, −15.473 to −2.124) showed a negative relationship with LS BMC via HOMA-IR.ConclusionsThese results support an intermediary role of insulin resistance in the relationship between adiposity and LS bone mass.

The biomedical program at PRIME Lab has prepared radiocarbon and 41Ca as tracers for a variety of applications. Over the last decade several hundred 14C samples and several thousand 41Ca samples have been measured per year. Biomedical samples pose challenges that are relatively rare in the AMS community. We will discuss how to prepare and compensate for samples that have isotope ratios above the dynamic range of AMS, high interference rates, and small samples sizes. In the case of 41Ca, the trade off in the chromatography between yield and sample cleanliness will be analyzed. Secondary standards that have isotope ratios commonly encountered in our applications are routinely prepared. We use material from the Joint Research Centre’s Institute for Reference Materials and Measurement: IRMM-3701/4, 3701/5, and 3701/6 and a standard produced by PRIME Lab for 41Ca. We use International Atomic Energy Agency’s IAEA C-3, IAEA C-7, IAEA C-8, and a ∼12.5× modern oxalic acid secondary standard supplied by Lawrence Livermore National Laboratory for 14C. We will discuss our precision, reproducibility, and the relative agreement between our measured and the reported values for these materials.

Background and objectives Twenty-four-hour urine phosphorus is commonly used as a surrogate measure for phosphorus intake and absorption in research studies, but its reliability and accuracy are unproven in health or CKD. This secondary analysis sought to determine the reliability and accuracy of 24-hour urine phosphorus as a biomarker of phosphorus intake and absorption in moderate CKD. Design, setting, participants, & measurements Eight patients with stage 3–4 CKD participated in 2-week balance studies with tightly controlled phosphorus and calcium intakes. Thirteen 24-hour urine collections per patient were analyzed for variability and reliability of 24-hour urine phosphorus and phosphorus-to-creatinine ratio. The accuracy of 24-hour urine phosphorus to predict phosphorus intake was determined using a published equation. The relationships of 24-hour urine phosphorus with phosphorus intake, net absorption, and retention were determined. Results There was wide day-to-day variation in 24-hour urine phosphorus within and among subjects (coefficient of variation of 30% and 37%, respectively). Two 24-hour urine measures were needed to achieve ≥75% reliability. Estimating dietary phosphorus intake from a single 24-hour urine resulted in underestimation up to 98% in some patients and overestimation up to 79% in others. Twenty-four-hour urine phosphorus negatively correlated with whole-body retention but was not related to net absorption. Conclusions From a sample of eight patients with moderate CKD on a tightly controlled dietary intake, 24-hour urine phosphorus was highly variable and did not relate to dietary phosphorus intake or absorption, rather it inversely related to phosphorus retention.

OBJECTIVES: Accurate estimates of sodium (Na) intake are critical for advancing our understanding of Na and cardiovascular disease. The aim of this study was to utilize data from a controlled feeding study to assess the agreement between estimated 24hUNa, calculated from several timed spot urine collections, and known Na intake. METHODS: This secondary analysis used data from the control phase of a potassium intervention study in normotensive men and women (n = 39) to avoid the potential confounding factor of dietary potassium manipulation. Participants followed the controlled diet containing on average 3463 mg Na/d for 3 days. On day 4, participants ate 3 meals in a clinic setting and collected urine every 2 hours starting with a fasting second void. The 24-hour urine collection was completed with the first morning void the following day. Spot urine samples were analyzed for Na and estimated 24hUNa was calculated from all samples using the INTERSALT and Tanaka equations, and from only the fasting second collection using the Kawasaki equation. The relationship between estimated 24hUNa and Na intake was assessed using Spearman correlations, and agreement between estimated 24hUNa and intake was assessed using Wilcoxon Signed Rank Tests and Bland Altman plots. RESULTS: For all timed spot urine samples, estimated 24hUNa using INTERSALT and Kawasaki were significantly correlated with Na intake (all P 0.05). For all timed spot urine samples, estimated 24hUNa using INTERSALT was significantly different from Na intake (all P

OBJECTIVES: Potassium is an essential nutrient of concern according to recent Dietary Guidelines for Americans Advisory Committees. Current recommendations established by the Institute of Medicine (IOM) are given as an Adequate Intake (AI) of 4700 mg/d, met by less than 3% of the population. Little is known about potassium (K) tissue retention and less is understood on how retention may affect health outcomes. In this clinical trial, we assessed the effects of K intake from potato sources and a K supplement on overall K balance. METHODS: Thirty pre-hypertensive-to-hypertensive (Systolic BP ≥ 120 mmHg) men (N = 15) and women (N = 15) with a mean ± SD age, BMI, and BP (systolic(SBP)/diastolic(DBP)) of 48.2 ± 15 y, 31.4 ± 6.1, and 136.3 ± 11.9/86.1 ± 7.1 mmHg, respectively, were enrolled in a cross-over randomized control diet trial. Participants were assigned to a random order of four 16-day dietary K interventions including a basal diet (control) of 2300 mg/d(∼60 mmol/d), and three periods of an additional 1000 mg/d(3300 mg/d(∼85 mmol/d) total) of K in the form of potatoes (baked, boiled, or pan-heated with no additional fat), French fries, or a K gluconate supplement. Each intervention period was separated by two or more weeks of wash out. Twenty-four hour urine and stool samples were collected throughout each intervention phase, and assessed via ICP-OES for K, sodium (Na), and calcium (Ca) content. Results for differences in mineral balance were assessed as % (%) of intake by 15-day sums as follows: retention = dietary intake – urine + stool losses. RESULTS: Using a mixed model with repeated measures and follow-up contrast analyses, initial analysis shows no significant differences (P > 0.05) in % mineral retention (± SE) for K (control: 28.92 ± 7.19, French fries: 30.37 ± 5.81, potatoes: 26.39 ± 5.11, supplement: 34.52 ± 6.53), Na (control: 23.42 ± 10.34, French fries: 30.37 ± 8.03, potatoes: 20.15 ± 6.86, supplement: 26.47 ± 10.14), or Ca (control: 25.21 ± 11.23, French fries: 16.61 ± 13.47, potatoes: 24.22 ± 4.56, supplement: 31.46 ± 8.22). CONCLUSIONS: Although there appears to be no difference in mineral retention due to source, these findings may challenge the current dogma that K and Na intake are equivalent to urinary output, and raise the question of how retention in various tissues can influence health outcomes. FUNDING SOURCES: The Alliance for Potato Research and Education.

Background According to traditional understanding of sodium homesostasis, nearly all of daily sodium intake is excreted in urine, with intra-individual variability attributed to variability in dietary sodium intake and urine collection errors. Objective To analyze the variability of urinary sodium in excretion from a balance study with fixed sodium intakes. Methods Daily 24-h urine collections were assessed for sodium, potassium, and creatinine in 22 black and 13 white adolescent girls (11-15 y, BMI 15-29 kg/m2) in a randomized, crossover design with controlled diets containing either low (57 mmol/d) or high (167 mmol/d) sodium, each fed for three weeks. Results Coefficients of variation (CV) analysis indicated higher variation in urinary sodium excretion about the mean on low (vs high) sodium (40% vs 32%, p=0.02) and in black (vs white) girls (42% vs 30%, p Conclusions The high intra-individual variability in urinary sodium excretion on a fixed diet highlights the potential for substantial error in (a) using a single 24-hr urine collection to estimate an individual’s usual sodium intake and (b) relating sodium excretion from a single 24-hr collection with outcomes. Further research is warranted to understand the causes of such variation.

Background: Calcium retention increases with increasing body mass index (BMI) on recommended calcium intakes. Dairy foods are an excellent source of essential nutrients that are needed to increase bone mineral content (BMC) and potentially decrease fracture.Objective: We compared children who were overweight with children who were healthy weight for the accrual of bone mass in response to an extra 3 servings dairy/d compared with usual intake.Design: Participants were 240 healthy boys and girls (64%), aged 8-15.9 y (mean ± SD age: 11.8 ± 1.5 y), who consumed low amounts of dairy (

Context:Vitamin D supplementation trials with diabetes-related outcomes have been conducted almost exclusively in adults and provide equivocal findings.Objective:The objective of this study was to determine the dose-response of vitamin D supplementation on fasting glucose, insulin, and a surrogate measure of insulin resistance in white and black children aged 9–13 years, who participated in the Georgia, Purdue, and Indiana University (or GAPI) trial: a 12-week multisite, randomized, triple-masked, dose-response, placebo-controlled vitamin D trial.Design:Black and white children in the early stages of puberty (N = 323, 50% male, 51% black) were equally randomized to receive vitamin D3 (0, 400, 1000, 2000, or 4000 IU/day) for 12 weeks. Fasting serum 25-hydroxyvitamin D (25(OH)D), glucose and insulin were assessed at baseline and weeks 6 and 12. Homeostasis model assessment of insulin resistance was used as a surrogate measure of insulin resistance. Statistical analyses were conducted as intent-to-treat using a mixed effects model.Results:Baseline serum 25(OH)D was inversely associated with insulin (r = −0.140, P = 0.017) and homeostasis model assessment of insulin resistance (r = −0.146, P = 0.012) after adjusting for race, sex, age, pubertal maturation, fat mass, and body mass index. Glucose, insulin, and insulin resistance increased (F > 5.79, P < .003) over the 12 weeks, despite vitamin D dose-dependent increases in serum 25(OH)D.Conclusions:Despite significant baseline inverse relationships between serum 25(OH)D and measures of insulin resistance, vitamin D supplementation had no impact on fasting glucose, insulin, or a surrogate measure of insulin resistance over 12 weeks in apparently healthy children.

BACKGROUND Dietary soluble corn fiber (SCF) significantly improves calcium absorption in adolescents and the bone strength and architecture in rodent models. OBJECTIVE In this study, we aimed to determine the skeletal benefits of SCF in postmenopausal women. DESIGN We used our novel technology of determining bone calcium retention by following the urinary appearance of (41)Ca, a rare long-lived radioisotope, from prelabeled bone to rapidly and sensitively evaluate the effectiveness of SCF in reducing bone loss. A randomized-order, crossover, double-blinded trial was performed in 14 healthy postmenopausal women to compare doses of 0, 10, and 20 g fiber from SCF/d for 50 d. RESULTS A dose-response effect was shown with 10 and 20 g fiber from SCF/d, whereby bone calcium retention was improved by 4.8% (P < 0.05) and 7% (P < 0.04), respectively. The bone turnover biomarkers N-terminal telopeptide and osteocalcin were not changed by the interventions; however, a significant increase in bone-specific alkaline phosphatase, which is a bone-formation marker, was detected between 0 and 20 g fiber from SCF/d (8%; P = 0.035). CONCLUSION Daily SCF consumption significantly increased bone calcium retention in postmenopausal women, which improved the bone calcium balance by an estimated 50 mg/d. This study was registered at clinicaltrials.gov as NCT02416947.

Scope Resistant starch (RS) is utilized by Gram-negative Bacteroidetes through a starch utilization system (Sus), which requires physical attachment of the bacteria to the substrate. Gram-positive Firmicutes, which include butyrate producers, utilize RS by other mechanisms, such as amylosomes and secreted amylases/glucoamylases. It has been previously shown that fabricated RS [alginate-based starch-entrapped microspheres (SM)] increases butyrate in in vitro human fecal fermentation and was slow fermenting. It has been hypothesized that in vivo SM would disfavor Bacteroidetes and promote Firmicutes, leading to an increase in butyrate production. Methods and results A C57BL/6J mouse model is used to test type 2 RS (RS2, raw potato) and SM for SCFAs and fecal microbial community structure. Feeding SM for 2 weeks results in 2.4 times higher mol% butyrate in the mouse distal gut than RS2. SM reduces relative abundance of Bacteroidetes and increases Firmicutes in fecal samples at the end of the 2-week feeding. This phylum-level taxonomic shift is not observed in animals fed RS2. Conclusion Through an approach to understand bacterial requirements related to starch utilization, a designed fiber type favors butyrogenic Firmicutes bacteria and provides higher mol% butyrate in the distal gut with potential benefit as an anti-inflammatory agent and to improve gut barrier function.

The bioavailability of potassium should be considered in setting requirements, but to our knowledge, the bioavailability from individual foods has not been determined. Potatoes provide 19-20% of potassium in the American diet.We compared the bioavailability and dose response of potassium from nonfried white potatoes with skin [targeted at 20, 40, and 60 milliequivalents (mEq) K] and French fries (40 mEq K) with potassium gluconate at the same doses when added to a basal diet that contained ∼60 mEq K.Thirty-five healthy, normotensive men and women with a mean ± SD age of 29.7 ± 11.2 y and body mass index (in kg/m(2)) of 24.3 ± 4.4 were enrolled in a single-blind, crossover, randomized controlled trial. Participants were partially randomly assigned to the order of testing for nine 5-d interventions of additional potassium as follows: 0 (control; repeated at phases 1 and 5), 20, 40, and 60 mEq K/d consumed as a potassium gluconate supplement or as unfried potato or 40 mEq K from French fries completed at phase 9. The bioavailability of potassium was determined from the area under the curve (AUC) of serial blood draws and cumulative urinary excretion during a 24-h period and from a kinetic analysis. The effects of the potassium source and dose on the change in blood pressure and augmentation index (AIx) were determined.The serum potassium AUC increased with the dose (P0.0001) and did not differ because of the source (P = 0.53). Cumulative 24-h urinary potassium also increased with the dose (P0.0001) and was greater with the potato than with the supplement (P0.0001). The kinetic analysis showed the absorption efficiency was high across all interventions (94% ± 12%). There were no significant differences in the change in blood pressure or AIx with the treatment source or dose.The bioavailability of potassium is as high from potatoes as from potassium gluconate supplements. Future studies that measure the effect of dietary potassium on blood pressure will need to evaluate the effect of various dietary sources on potassium retention and in both normal and hypertensive populations. This trial was registered at clinicaltrials.gov as NCT01881295.

Background Calcium is a shortfall essential nutrient that has been a mainstay of osteoporosis management. Recent and limited findings have prompted concern about the contribution of calcium supplementation to cardiovascular risk. A proposed mechanism is through the acceleration of coronary artery calcification. Determining causality between calcium intake and coronary artery calcification has been hindered by a lack of sensitive methodology to monitor early vascular calcium accumulation. The primary study aim was to assess the impact of high calcium intake on coronary artery calcification using innovative calcium tracer kinetic modeling in Ossabaw swine with diet‐induced metabolic syndrome. Secondary end points (in vitro wire myography, histopathology, intravascular ultrasound) assessed coronary disease. Methods and Results Pigs (n=24; aged ≈15 months) were fed an atherogenic diet with adequate calcium (0.33% by weight) or high calcium (1.90% from calcium carbonate or dairy) for 6 months. Following 5 months of feeding, all pigs were dosed intravenously with 41 Ca, a rare isotope that can be measured in serum and tissues at a sensitivity of 10 −18 mol/L by accelerator mass spectrometry. Kinetic modeling evaluated early coronary artery calcification using 41 Ca values measured in serial blood samples (collected over 27 days) and coronary artery samples obtained at sacrifice. Serum disappearance of 41 Ca and total coronary artery 41 Ca accumulation did not differ among groups. Secondary end points demonstrated no treatment differences in coronary artery disease or function. Conclusion There was no detectable effect of high calcium diets (from dairy or calcium carbonate) on coronary artery calcium deposition in metabolic syndrome swine.

Hesperidin is a flavonoid derived from citrus fruits that has been shown to improve bone mass and strength in pre-clinical studies in rodents. This double blind randomized order cross-over study wa...

Potassium is a shortfall nutrient according to the 2010 Dietary Guidelines for Americans. Only 3% of Americans meet the recommended Adequate Intake of 4700 mg/d for potassium. Bioavailability of potassium has not been considered in setting requirements as no food has been tested. Among adult potato consumers potatoes provide 19-20% of potassium in the diet. The aim of this study was to compare bioavailability and dose response of potassium from non-fried white potatoes with skin with potassium gluconate. Thirty five healthy, normotensive men and women with a mean age of 29.7 (+/- 11.2) years and BMI of 24.3 (+/- 4.4) kg/m2 (mean +/- (SD)) were enrolled in this single-blind, cross-over, randomized controlled trial. Participants were randomized to 1 of 8 interventions of potassium: 0 (control repeated twice), 720 (~18.5), 1440 (~37), 2160 (~55.5) mg/day (mEq/day) consumed as a potassium gluconate supplement or white potato with skin added to the basal diet containing ~2300 mg/day (~60 mEq/day) potassium. Bi...