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Provides information on how to evaluate a nutrition research article. Source and authors; Criteria for evaluating the methodology; Questions for discussion and conclusion.

Abstract The World Health Organization has classified boron as 'a trace element that is probably essential'. Boron participates in or regulates a number of metabolic pathways including oestrogen and testosterone synthesis, calcium homeostasis and embryonic growth. Because of its involvement in steroid hormone metabolism, dietary boron has been suggested as having an important role in a number of chronic diseases and in vertebrate development. Extrapolations of data derived from experiments in animals suggest that humans have a boron requirement of 0.5 to 1.0 mg/day. There is uncertainty about the mechanisms through which boron acts. More research is warranted before boron is considered of more clinical and nutritional importance than currently acknowledged. Although there is uncertainty about the mechanisms through which boron acts, there is good evidence that it may impact on disease prevention. Future research should focus on defining the saftey margin between toxic and essential doses and assess its possible therapeutic use. (Aust J Nutr Diet 2001;58:104-106) [ABSTRACT FROM AUTHOR]

Ethnic groups in affluent environments experience higher rates of metabolic diseases than their native counterparts. Our objective was to determine the prevalence of metabolic risk factors in Ghanaians in Sydney, and to investigate the relationship with dietary and lifestyle factors. Cross-sectional design with anthropometry, blood pressure, plasma lipids, glucose and insulin concentrations were measured on two occasions on each subject. Dietary information was obtained by three 24-h dietary recalls. Adults (45 male, 35 female) were recruited from a local association in Sydney, Australia. Overweight was observed in a large proportion of subjects (71% and 66% of men and women, respectively), with 18% of men and 26% of women classified as obese. Abdominal overweight was seen in 63% and 74% of men and women, respectively. Abdominal obesity was seen in 20% of men and 49% of women. Hypertension was detected in 40% of men and 17% of women, 16% of men and 6% of women were diagnosed with definite hypertension. Seventy-one per cent of men and 29% of women were classified as hypercholesterolaemic and 67% of men and 23% of women had elevated low-density lipoprotein cholesterol. In men, low high-density lipoprotein cholesterol and hypertriacylglycerolaemia affected 18% and 13%, respectively. Fasting hyperinsulinaemia was observed in 14% and 9% of men and women, respectively. The majority of subjects (73%) sustained one or more metabolic risk factors. Dietary fat contributed 33% and 35% of total energy intake in men and women, respectively, saturated fat contributing 11% in both sexes. A high prevalence of overweight, diabetes, hypertension and dyslipidaemia exists in this population, particularly in men, highlighting the need for intervention. [ABSTRACT FROM AUTHOR]

Background: Diabetes is increasing in incidence, morbidity and treatment costs globally, hence prevention strategies need to be explored. Animal studies and some human data have shown that zinc can improve glycaemic control, but the impact of this effect in a pre-diabetic population remains uncertain. This study is designed to investigate whether zinc gluconate and lifestyle coaching can improve glucose handling and ultimately reduce diabetes incidence in an at-risk pre-diabetic population in Australia.Methods/design: The study will be a randomised, placebo-controlled, double-blind clinical trial. The study will be conducted at the Hunter New England Local Health District New South Wales (NSW), Australia. Pre-diabetic (haemoglobin A1c [HbA1c] 5.7-6.4) male and female participants (n = 410) aged 40-70 years will be recruited through the Diabetes Alliance Network, a collaboration of diabetes specialists and general practitioner practices. All participants will be given routine care to encourage healthy lifestyle changes using a telephone coaching service (Get Healthy Information and Coaching Service, NSW Health) and then randomised to receive a supplement, either zinc gluconate (equivalent to 30 mg of elemental zinc) or placebo of identical appearance for 12 months. The identity of the supplements will be blinded to both research personnel and the participants. Participants will be asked to complete medical, lifestyle and dietary surveys and will have baseline and final visits at their general practitioner practice. Primary outcomes will be HbA1c and insulin sensitivity collected at baseline and at 1, 6 and 12 months; secondary outcomes will include fasting blood glucose, fasting cholesterol, blood pressure and body mass index. The primary efficacy endpoint will be judged at 6 months.Discussion: This study will generate new evidence about the potential for health coaching, with or without zinc supplementation, to improve glucose handling and ultimately to reduce progression from pre-diabetes to diabetes.Trial Registration: Australian and New Zealand Clinical Trials Registry, ACTRN12618001120268 . Registered on 6 July 2018. [ABSTRACT FROM AUTHOR]

Introduction: Neopterin, kynurenine and tryptophan can be used to measure activation of monocytes and macrophages during immunological events such as exercise inducing inflammation. Endurance exercise and high-impact sports have shown significant increases in these biomarkers. Measurement is typically conducted by high-performance liquid chromatography (HPLC) using C18 or SCX columns. However, kynurenine and tryptophan are not measured simultaneously to neopterin using these separation systems. Here we have used an amine column for separation and simultaneous determination of neopterin, kynurenine and tryptophan. Methods: Optimization and validation for the amine-HPLC method was conducted using plasma from 43 participants subjected to a short maximal exercise bicycling regime or rest period. The order of exercise and rest was randomized and separated by a 3-5 week washout period. Results: Using an amine column developed with ammonium acetate formic acid (33%) and acetonitrile (72%) provided optimal separation and run time for analysis. Neopterin increased significantly post-exercise and subsided to baseline by 30 minutes. Total neopterin remained elevated until 60 minutes following exercise. Conclusion: Amine-HPLC can be used for simultaneous determination of kynurenine, tryptophan and neopterin in plasma. Short intense exercise causes a significant increase in plasma neopterin suggesting a prolonged activation of monocytes and macrophages. [ABSTRACT FROM AUTHOR]

Purpose: Population studies of the association between zinc intake and mortality yield inconsistent findings. Using data from Jiangsu Nutrition Study, we aimed to assess the association between zinc intake and mortality among Chinese adults.Methods: We prospectively studied 2832 adults aged 20 years and older with a mean follow-up of 9.8 years. At baseline, food intake was measured by 3-day weighed food record (WFR) between September and December in 2002. Death occurrence was assessed in 2012 during a household visit as well as by data linkage with the regional death registry. Hazard ratios (HRs) and 95% CI were calculated using competing risks regression (CVD and cancer mortality) and Cox proportional hazards analysis (all-cause mortality).Results: During 27,742 person-years of follow-up, there were 184 deaths [63 cancer deaths and 70 cardiovascular disease (CVD) deaths]. Dietary zinc to energy ratio was positively associated with cancer and all-cause mortality. Across quartiles of the zinc to energy ratio from low to high, the HR (95% CI) for all-cause mortality was 1.00, 1.80 (95% CI 1.10-2.95), 1.55 (95% CI 0.96-2.50), and 1.85 (95% CI 1.11-3.07), respectively. Comparing the extreme quartiles of the zinc to energy ratio, the HR for cancer mortality was 2.28 (95% CI 1.03-5.04).Conclusion: Zinc intake was positively related to all-cause mortality and cancer mortality. [ABSTRACT FROM AUTHOR]

Background: Zinc has a critical role in metabolism and growth. This study aims to determine the effects of lowenergy diets differing in macronutrient composition on zinc intake, estimated zinc bioavailability (phytate:zinc molar ratio) and plasma zinc concentration and associations between zinc status and cardiometabolic markers in obese adolescents with clinical insulin resistance (IR). Methods: Eighty-seven obese adolescents (10-17 years, body mass index z-score 2.3 ± 0.37) with clinical IR were randomized to a low-energy diet (6.0-8.0 MJ), which was either high carbohydrate or moderate carbohydrate with increased protein. Twenty-four-hour dietary recalls were collected at 6, 9 and 12 weeks. Plasma zinc concentration and cardiometabolic markers were assessed at baseline and 12 weeks. Results: Zinc intake did not differ between the 2 diet groups (p = 0.612). The high-carbohydrate group had a higher phytate intake (894 vs. 671 mg, p = 0.018) and phytate:zinc molar ratio (9.4 vs. 7.4, p = 0.009) than the increased-protein group. Plasma zinc concentration did not change from baseline in either of the diet groups, but correlated positively with zinc intake (r = 0.235, p = 0.042) and % energy from protein (r = 0.383, p = 0.001), and inversely with % energy from carbohydrate (r = -0.296, p = 0.010). Conclusions: Low energy diets for obese adolescents at risk of diabetes may need increased protein content to optimize zinc bioavailability. [ABSTRACT FROM AUTHOR]

Abstract: Limited information is available on the role of iron in fatty acid metabolism in humans. We hypothesized that iron supplementation will increase desaturase activity, and so, the aim of this study was to determine the effect of iron supplementation on fatty acid desaturase activity in young women. Participants were randomly assigned to a control group (CG) or supplementation group (SG) who were provided with 37.4 mg of elemental iron daily for 12 weeks. Forty women completed the trial, n = 19 in CG and n = 21 in SG. The mean ages were 25.2 and 24.6 years, and body mass indices were 21.8 and 21.2 (kg/m2) in CG and SG, respectively. Serum ferritin concentrations increased significantly (P < .01) in subjects assigned to SG but were unchanged in CG. Serum iron concentrations were not significantly changed. Plasma zinc concentrations at the end of the intervention were similar to baseline values for individuals in CG but were decreased significantly (P = .004) in SG. Plasma fatty acids, phospholipid fatty acids, and desaturase activities, expressed as precursor-to-product ratios, were not significantly affected by the intervention, although in SG the concentration of serum ferritin was correlated positively (P < .05) with Δ6-desaturase activity. Supplementing non-anemic women with low dose iron improves iron status but has no significant effect on desaturase activity. The lack of a clear effect on an indirect indicator of desaturase activity may be related to the antagonism between iron and zinc, as illustrated by the decrease in plasma zinc concentrations in women who were supplemented with iron. [Copyright &y& Elsevier]

The zinc transporter (ZnT; SLC30) and Zrt- and Irt-like protein (Zip, SLC39) zinc transporter families are integral to the maintenance of intracellular zinc concentrations. Few studies have examined the expression patterns of zinc transporter genes in human primary tissues. This study investigated the expression levels of a range of zinc transporter mRNA in the peripheral blood mononuclear cells of healthy men and women (n = 40) using quantitative real-time PCR. It also explored the relationships among zinc transporter expression levels, plasma zinc concentrations and dietary zinc intake. The relative expression of the zinc transporter mRNA varied considerably, with ZnT7, ZnT7, and Zip1 being the most abundantly expressed. ZnT1 and Zip1 mRNA were highly correlated with one another (r = 0.9; P < 0.001) and with ZnT5, ZnT7, Zip3, and Zip10 (P < 0.001). When analyzed by gender, a correlation between the mRNA of ZnT7 and Zip3 (r = 0.6; P< 0.0) was demonstrated only in women. Zip10mRNA was correlated with ZnT1 and Zip1 (r= 0.9; P< 0.001) in men only. In a regression analysis, plasma zinc variability was not significantly explained by dietary zinc intake, gender, age, or any individual or combination of zinc transporters. This study expands what is known-about both the levels of zinc transporter gene transcription in humans and the extent of its variation in healthy men and women. The positive association between the mRNA of ZnT1 and Zip1, which have reciprocal roles in zinc transport across the plasma membrane, provides insight into the coordinated control of zinc homeostasis in humans. [ABSTRACT FROM AUTHOR]

Abstract: Folate, vitamin B12, iron, and zinc are particularly important nutrients for women of childbearing age. We tested the hypothesis that an electronic, 235-item, semiquantitative food frequency questionnaire (FFQ) is a valid measure of dietary intake when compared with repeat dietary 24-hour recalls. Biomarkers of folate, vitamin B12, iron, and zinc were determined because their measurement errors are unrelated to errors in dietary questionnaires. Female adults (N = 256) aged 18 to 35 years completed the FFQ, and a representative subset (n = 53) completed repeat dietary 24-hour recalls. The FFQ estimates (mean ± SD) were 315 ± 132 μg for folate, 3.1 ± 2.1 μg for vitamin B12, 15.4 ± 5.6 mg for iron, and 15.1 ± 6.4 mg for zinc. The percentage of women classified within the same ±1 quartile for energy intake by the 2 methods was 77.3%. There was moderate agreement between the 2 dietary methods, and no systematic bias was noted for energy, folate, vitamin B12, and zinc. The deattenuated energy-adjusted correlation coefficients ranged from 0.41 (dietary folate equivalents) to 0.60 (folate). Significant correlations between biomarker and nutrient intakes were found for folate (r = 0.37, P < .01) and vitamin B12 (r = 0.27, P < .01). The electronic FFQ developed in the present study is a relatively valid tool that was able to adequately assess and rank individuals according to their nutrient intakes. [Copyright &y& Elsevier]

The article focuses on the study that compares the relative effects of low-glycemic index (GI) and high-protein diets on weight loss and cardiovascular risk. High carbohydrate intake can exaggerate postprandial glycemia and has accompanied increases in obesity, type 2 diabetes mellitus, and the effects of energy expenditure. Findings show that both high-protein and low-GI regimens increase body fat loss.

Phenolic compounds have been shown to exhibit bioactive properties, and in particular antioxidant effects. A phenolic-rich fraction has been isolated from the aqueous by-product obtained during the milling of oil palm fruits. The objectives of the study were to determine the phenolic content of the crude and ethanolic extracts of oil palm fruits and to evaluate the antioxidant properties of these extracts. The total phenolics content of the crude and ethanol extracts as determined by the Folin-Ciocalteu method were found to be 40.3 +/- 0.5 and 49.6 +/- 0.6 mg GAE/g extract (dry basis), respectively. The radical scavenging activity of the extracts determined using 2,2 diphenyl-1-picrylhydrazyl radical (DPPH.) indicated that both crude and ethanol extracts exhibit hydrogen-donating capacity, and have antiradical power (ARP) comparable to ascorbic acid. The DPPH radical scavenging activity of the extracts were less than that of gallic acid, but the time-course variations of the scavenging curves suggest that the extracts acted by a mechanism similar to that of gallic acid. The electron-donating potentials of the extracts were inferred from the hydrogen peroxide scavenging and reducing power assays. The reducing power of crude and ethanol extracts at 1 mM GAE were found to be comparable to that of 0.3 mM gallic acid. The extracts indicated complete scavenging of hydrogen peroxide at concentrations above 0.4 mM GAE. These findings suggest that the crude and ethanol extracts are able to scavenge free radicals, by either hydrogen or electron donating mechanisms, and can therefore act as primary antioxidants. [ABSTRACT FROM AUTHOR]

Background - Phenolic compounds have been shown to exhibit bioactive properties, and in particular antioxidant effects. A phenolic-rich fraction has been isolated from the aqueous byproduct obtained during the milling of oil palm fruits (1). Objective - To characterise the phenolic compounds obtained from crude and ethanolic extracts of oil palm fruits and to evaluate the antioxidant properties of these extracts. Design - Characterisation of the profile of phenolics by NMR spectroscopy and evaluation of antioxidant properties using the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH.), reducing power, and hydrogen peroxide scavenging assays. Outcomes - NMR studies indicate that both extracts consist of mixtures of sugars and phenolic compounds, of which gallic acid and 4-hydroxybenzoate predominate. The antiradical power (ARP, mole ratios expressed in arbitrary units) of the crude extract (3.14) and ethanol extract (3.31), measured by the DPPH. assay were comparable to the ARP of ascorbic acid (3.78). Crude and ethanol extracts of 1mM gallic acid equivalence (GAE) had reducing powers comparable to that of 0.3 mM gallic acid. In the hydrogen peroxide scavenging assay, 100% scavenging was achieved at concentration of 0.3 mM GAE for both crude and ethanol extracts. Conclusions - These findings suggest that oil palm fruit extracts are able to act as primary antioxidants by their hydrogen- and electron-donating capacity. Similar findings have been reported for extracts from olives and tea. These preliminary observations also suggest that oil palm fruit extracts are potential sources of nutraceuticals. [ABSTRACT FROM AUTHOR]

Background & Aim: The gut-brain axis is one of the proposed interactions between the brain and peripheral intestinal functions; of particular interest is the influence of food components on the gut-brain axis mediated via the gut microbiome. Probiotics and paraprobiotics have been proposed to interact with the intestinal environment and provide health benefits such as improving sleep quality. The aim of this research was to undertake a systematic literature review and meta-analysis to evaluate the current evidence regarding the effects of Lactobacillus gasseri CP2305 on sleep quality for the general population., Methods: A systematic literature search was conducted of peer-reviewed articles published up to 04 November 2022. Randomised controlled trials were identified that investigated the effects of Lactobacillus gasseri CP2305 on sleep parameters in adults. Meta-analysis of the change in the Pittsburgh Sleep Quality Index (PSQI) global score was conducted. Quality assessments of individual studies were conducted using the Cochrane Risk of Bias and Health Canada tools., Results: Seven studies were included in the systematic literature review; six studies included data for meta-analysis to quantify the effect of L. gasseri CP2305 on sleep quality. The ingestion of L. gasseri CP2305 resulted in significant improvement in the PSQI global score compared to control (-0.77, 95% CI: -1.37 to -0.16, P = 0.01). In the two studies that included electroencephalogram (EEG) data, output was significantly improved for at least half of the measured EEG outcomes after consumption of L. gasseri CP2305. No serious concerns were found in the potential biases of included studies, indirectness of the included evidence, and other methodological issues., Conclusion: The present systematic review and meta-analysis indicates significant improvement in sleep quality of adults with mild to moderate stress as an effect of daily consumption of L. gasseri CP2305. Based on existing evidence, the relationship between L. gasseri CP2305 and enhanced sleep quality is plausible, however further investigations are required to confirm the mechanisms of actions for this effect., Competing Interests: Conflicts of interest The authors declare no conflicts of interest., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Aims: The burden and health costs of Type 2 Diabetes Mellitus continue to increase globally and prevention strategies in at-risk people need to be explored. Previous work, in both animal models and humans, supports the role of zinc in improving glucose homeostasis. We, therefore, aimed to test the effectiveness of zinc supplementation on glycaemic control in pre-diabetic adults., Methods: We conducted a randomized, double-blind, placebo-controlled trial across 10 General Practitioner (GP) practices in NSW, Australia. The trial is known as Zinc in Preventing the Progression of pre-Diabetes (ZIPPeD)Study. Pre-diabetic (haemoglobin A1c [HbA1c] 5.7-6.4%, 39-46 mmol/mol) men and women (N = 98) were all assigned to a free state government telephone health coaching service (New South Wales Get Healthy Information and Coaching Service) and then randomised to either daily 30 mg zinc gluconate or placebo. Blood tests were collected at baseline, 1, 6 and 12 months for the primary outcomes (HbA1c, fasting blood glucose (FBG)); secondary outcomes included Homeostasis Model Assessment 2 (HOMA 2) parameters, lipids, body weight, height, waist circumference, blood pressure and pulse., Results: The baseline-adjusted mean group difference at 6 months, expressed as treatment-placebo, (95% CI) was -0.02 (-0.14, 0.11, p = 0.78) for HbA1c and 0.17 (-0.07, 0.42; p = 0.17) for FBG, neither of which were statistically significant. There were also no significant differences between groups in any of the secondary outcomes. Zinc was well tolerated, and compliance was high (88%)., Conclusion: We believe our results are consistent with other Western clinical trial studies and do not support the use of supplemental zinc in populations with a Western diet. There may still be a role for supplemental zinc in the developing world where diets may be zinc deficient., Trial Registration: Australian and New Zealand Clinical Trials Registry, ACTRN12618001120268. Registered on 6 July 2018., (© 2022. The Author(s).)

Objective: To identify the optimal AUSDRISK threshold score to screen for pre-diabetes and diabetes., Methods: A total of 406 adult patients not diagnosed with diabetes were screened in General Practices (GP) between May and October 2019. All patients received a point of care (POC) HbA1c test. HbA1c test results were categorised into diabetes (≥6.5% or ≥48 mmol/mol), pre-diabetes (5.7-6.4% or 39-47 mmol/mol), or normal (<5.7% or 39 mmol/mol)., Results: Of these patients, 9 (2%) had undiagnosed diabetes and 60 (15%) had pre-diabetes. A Receiver Operator Characteristic (ROC) curve was constructed to predict the presence of pre-diabetes and diabetes; the area under the ROC curve was 0.72 (95%CI 0.65-0.78) indicating modest predictive ability. The optimal threshold cut point for AUSDRISK score was 17 (sensitivity 76%, specificity 61%, + likelihood ratio (LR) 1.96, - likelihood ratio of 0.39) while the accepted cut point of 12 performed less well (sensitivity 94%, specificity 23%, +LR=1.22 -LR+0.26)., Conclusions: The AUSDRISK tool has the potential to be used as a screening tool for pre-diabetes/diabetes in GP practices. A cut point of ≥17 would potentially identify 75% of all people at risk and three in 10 sent for further testing would be positive for prediabetes or diabetes., Implications for Public Health: Routine case-finding in high-risk patients will enable GPs to intervene early and prevent further public health burden from the sequelae of diabetes., (© 2021 The Authors.)

Zinc status is implicated in physiological functions related to exercise performance and physical activity. We have previously demonstrated significant changes in serum zinc concentrations following a bout of aerobic exercise, suggestive of a relationship between zinc metabolism and exercise-related functions. In the present study, we aim to determine the association between pre-exercise serum zinc concentration and immediate changes in serum zinc concentration following an aerobic exercise bout. We have previously conducted a systematic literature search of PubMed, Web of Science, Scopus and SPORTDiscus, for studies that investigated the acute effects of aerobic exercise on zinc biomarkers. In the current study, we undertook a secondary analysis using mixed effects meta-regression modelling to determine the relationship between baseline serum zinc concentration and the change in serum zinc concentration immediately after exercise. Meta-regression models revealed no significant relationship between baseline serum zinc concentration and the change in serum zinc concentration following a bout of exercise when all comparisons were included (slope -0.11 ± 0.07 [standard error]; P > 0.05). When comparisons were stratified by exercise modality, no significant relationships were observed for exercise bouts involving cycling or running. The current analyses were limited by the available literature and low statistical power of the meta-regression models. Based on the current available data, the present analysis revealed limited evidence for a relationship between pre-exercise serum zinc concentration and immediate changes in serum zinc levels following a bout of aerobic exercise. Subgroup meta-regression analyses stratified by the mode of exercise bouts did not differ from the overall results. This suggests that zinc status at baseline is not related to acute changes in serum zinc concentration following bouts of aerobic exercise., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Background: Little is known about zinc intakes and status during complementary feeding. This is particularly true for baby-led approaches, which encourage infants to feed themselves from the start of complementary feeding, although self-feeding may restrict the intake of zinc-rich foods., Objective: To determine the zinc intakes, sources, and biochemical zinc status of infants following Baby-Led Introduction to SolidS (BLISS), a modified version of Baby-Led Weaning (BLW), compared with traditional spoon-feeding., Design: Secondary analysis of the BLISS randomized controlled trial., Participants/setting: Between 2012 and 2014, 206 community-based participants from Dunedin, New Zealand were randomized to a Control or BLISS group., Intervention: BLISS participants received eight study visits (antenatal to 9 months) providing education and support regarding BLISS (ie, infant self-feeding from 6 months with modifications to address concerns about iron, choking, and growth)., Main Outcome Measures: Dietary zinc intakes at 7 and 12 months (weighed 3-day diet records) and zinc status at 12 months (plasma zinc concentration)., Statistical Analyses Performed: Regression analyses were used to investigate differences in dietary intakes and zinc status by group, adjusted for maternal education and parity and infant age and sex., Results: There were no significant differences in zinc intakes between BLISS and Control infants at 7 (median: 3.5 vs 3.5 mg/day; P=0.42) or 12 (4.4 vs 4.4 mg/day; P=0.86) months. Complementary food groups contributing the most zinc at 7 months were "vegetables" for Control infants, and "breads and cereals" for BLISS infants, then "dairy" for both groups at 12 months. There was no significant difference in mean±standard deviation plasma zinc concentration between the Control (62.8±9.8 μg/dL [9.6±1.5 μmol/L]) and BLISS (62.8±10.5 μg/dL [9.6±1.6 μmol/L]) groups (P=0.75)., Conclusions: BLISS infants achieved similar zinc intake and status to Control infants. However, the BLISS intervention was modified to increase iron intake, which may have improved zinc intake, so these results should not be generalized to infants following unmodified BLW., (Copyright © 2018 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.)

Background: Zinc is an essential trace element that has been implicated in numerous biological functions, including immunity, energy metabolism and antioxidative processes. Recent evaluations of the literature have provided evidence of significant acute changes in zinc metabolism following a bout of aerobic exercise., Objective: The aim of this study was to determine the zinc status of trained athletes compared with control populations, as described in cross-sectional studies., Design: We conducted a systematic literature search of the PubMed, Scopus, SPORTDiscus and Cochrane Library electronic databases from inception to 28 January 2016 to identify cross-sectional studies that determined the zinc status of athletes compared with a control population. Meta-analysis of the differences in serum zinc concentration and dietary zinc intake between groups were conducted., Results: Twelve studies were included in the systematic review. Of the included studies, nine and eight studies provided sufficient data for the meta-analysis of serum zinc concentration and dietary zinc intake, respectively. Serum zinc concentration was significantly lower in athletes [- 0.93 μmol/L, 95% confidence interval (CI) - 1.62 to - 0.23] despite significantly higher dietary zinc intake compared with the control population (2.57 mg/day, 95% CI 0.97-4.16). Data on erythrocyte and urinary zinc from the included studies were insufficient for meta-analysis., Conclusions: Despite higher total dietary zinc intake, athletes generally have lower serum zinc concentration, which suggests that athletes have higher requirement of zinc than those who are physically inactive. Further investigations of zinc metabolism during exercise and dietary zinc requirement in active populations are needed to establish evidence-based recommendations.

Background: Exercise and the subsequent recovery processes have been proposed to induce disturbances in zinc homeostasis. We previously reported acute increase in serum zinc concentration immediately after aerobic exercise; the change in the indices of zinc status during exercise recovery was not explored., Objective: The aim of the current analysis is to determine the changes in zinc biomarkers during recovery from an aerobic exercise bout., Methods: We conducted a systematic literature search on PubMed, Web of Science, Scopus and SPORTDiscus electronic databases from inception to 20 December 2014 to identify studies that investigated the acute effects of exercise on selected indices of zinc status. Meta-analyses were conducted to determine the change in serum zinc concentration during exercise recovery, defined as up to 4 h following exercise cessation, compared to pre-exercise levels., Results: Forty-five studies were included in the systematic literature review, of which 12 studies (providing 18 comparisons) reported serum zinc levels after the cessation of exercise. During exercise recovery, serum zinc concentration was significantly lower than pre-exercise values (-1.31 ± 0.22 μmol/L, P < 0.001; mean ± SE). Secondary analyses showed a significant decrease of serum zinc levels in all categories of participants' training status, mode of exercise and time of blood collection. Insufficient data were available for meta-analysis of other zinc biomarkers., Conclusions: The present analysis showed that serum zinc levels decrease significantly during exercise recovery, compared to pre-exercise levels. This extends our previous report of an increase in serum zinc immediately after exercise. We postulate that the exercise-induced fluctuations in zinc homeostasis are linked to the muscle repair mechanisms following exercise; the potential for zinc to enhance the exercise recovery process remains to be determined.

Background: Zinc is involved in numerous metabolic roles, including energy metabolism, immunity, and antioxidative effects. Zinc losses during exercise, in particular through sweat, are well documented. However, conflicting results have been reported for changes in circulating and tissue zinc concentration as a result of exercise. The purpose of this article is to quantify the immediate effect of aerobic exercise on plasma or serum zinc levels, in healthy participants., Methods: We conducted a systematic review of peer-reviewed articles published up to December 20, 2014, to identify studies that investigated the acute effects of exercise on selected indices of zinc status. Meta-analyses were conducted to determine the change in serum zinc concentration immediately after a bout of aerobic exercise., Results: Forty-five studies were included in the systematic literature review. Of the included studies, sufficient data were available from 34 studies (providing 46 comparisons) to quantify the change in serum zinc concentration after exercise. Serum zinc concentration was significantly higher immediately after exercise (0.45 ± 0.12 μmol·L(-1), P < 0.001; mean ± SE). Secondary analyses showed greater increase in serum zinc for untrained individuals and exercise sessions that involved running or maximal intensity. Insufficient data were available to determine the effects of exercise on urinary, sweat, and erythrocyte zinc., Conclusions: The present systematic review and meta-analysis indicated significant increase in serum zinc concentration immediately after an aerobic exercise session, suggesting acute perturbations in zinc homeostasis. Further research is required to ascertain the long-term effects of exercise on zinc metabolism and potential consequences for dietary zinc requirement for physically active populations.

Optimal zinc status is an important consideration when evaluating the nutritional adequacy of vegetarian diets. In the absence of animal tissue sources of zinc and with increased intake of inhibitors of zinc absorption, phytic acid in particular, the bioavailability of zinc is thought to be lower from vegetarian as compared to omnivorous diets. The aim of this chapter is to review the research that examines the effects of vegetarian compared to omnivorous diets on zinc intake and zinc status in the elderly, adults, children, pregnancy, and lactation. A narrative review of the published literature was undertaken, focusing on observational studies in humans that reported zinc intake and biomarkers of zinc status at various stages of the life cycle. Compared to their respective nonvegetarian control groups, adult male and female vegetarians have lower dietary zinc intakes and serum zinc concentrations. However in the elderly, children, and in women during pregnancy and lactation, there is insufficient evidence to determine whether zinc intake and status are lower in vegetarians compared to omnivores. Inconsistencies in study findings reflect variations inherent in the definition of vegetarian diets, and in many instances compromised statistical power due to a small sample size. Improved methods for the assessment of zinc status are required to determine whether homeostatic responses are sufficient to maintain an adequate zinc status in vegetarians, particularly during times of increased requirement. Appropriate dietary advice to increase the zinc content and bioavailability of vegetarian diets throughout the life cycle is prudent., (© 2015 Elsevier Inc. All rights reserved.)

Type 2 diabetes mellitus (DM) is associated often with underlying zinc deficiency and nutritional supplements such as zinc may be of therapeutic benefit in the disease. In a randomized, double-blind, placebo-controlled, 12-week trial in postmenopausal women (n=48) with Type 2 DM we investigated the effects of supplementation with zinc (40mg/d) and flaxseed oil (FSO; 2g/d) on the gene expression of zinc transporters (ZnT1, ZnT5, ZnT6, ZnT7, ZnT8, Zip1, Zip3, Zip7, and Zip10) and metallothionein (MT-1A, and MT-2A), and markers of glycemic control (glucose, insulin, glycosylated hemoglobin [HbA1c]). The homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. No significant effects of zinc or FSO supplementation were observed on glycemic marker concentrations, HOMA-IR or fold change over 12 weeks in zinc transporter and metallothionein gene expression. In multivariate analysis, the change over 12 weeks in serum glucose concentrations (P=0.001) and HOMA-IR (P=0.001) predicted the fold change in Zip10. In secondary analysis, marginal statistical significance was observed with the change in both serum glucose concentrations (P=0.003) and HOMA-IR (P=0.007) being predictive of the fold change in ZnT6. ZnT8 mRNA expression was variable; HbA1c levels were higher (P=0.006) in participants who exhibited ZnT8 expression compared to those who did not. The significant predictive relationships between Zip10, ZnT6, serum glucose and HOMA-IR are preliminary, as is the relationship between HbA1c and ZnT8; nevertheless the observations support an association between Type 2 DM and zinc homeostasis that requires further exploration., (Copyright © 2014 Elsevier GmbH. All rights reserved.)

Background: Impaired zinc metabolism is prominent in chronic disorders including cardiovascular disease and diabetes. Zinc has the potential to affect glucose homeostasis in animals and humans and hence impact the risk of type 2 diabetes mellitus., Methods: A systematic review and meta-analysis of randomised placebo controlled trials was conducted to determine the effect of zinc supplementation on fasting blood glucose, HbA1c, serum insulin and serum zinc concentrations. Relevant studies for inclusion were identified from a literature search of electronic databases up to July 2011., Results: Fourteen reports (n=3978 subjects) were included in the meta-analysis. In the overall analysis, a small but statistically significant reduction in fasting glucose concentrations was observed (-0.19±0.08mmol/L, P=0.013) after zinc supplementation. HbA1c tended to decrease in zinc-supplemented individuals (-0.64±0.36%, P=0.072). No significant effect was observed for serum insulin concentrations. Plasma zinc concentrations increased significantly following supplementation (+4.03±0.81μmol/L, P=0.001). In secondary analyses of participants with chronic metabolic disease (types 1 and 2 diabetes mellitus, metabolic syndrome and obesity), zinc supplementation produced a greater reduction in glucose concentrations (-0.49±0.11mmol/L, P=0.001) compared to the effect that was observed in healthy participants., Conclusion: The significant albeit modest reduction in glucose concentrations and tendency for a decrease in HbA1c following zinc supplementation suggest that zinc may contribute to the management of hyperglycemia in individuals with chronic metabolic disease., (Copyright © 2012 Elsevier GmbH. All rights reserved.)

Phytic acid is a major determinant of zinc bioavailability. Little is known about phytic acid intakes or indices of zinc bioavailability in type 2 diabetes mellitus (DM), a condition that predisposes to zinc deficiency. The aim of this cross-sectional study was to measure and explore the relationships among phytic acid intake, zinc bioavailability, and molecular markers of zinc homeostasis in 20 women with DM compared to 20 healthy women. The phytate/zinc, (calcium)(phytate)/zinc, and (calcium + magnesium)(phytate)/zinc molar ratios were used to indicate zinc bioavailability. Plasma zinc concentrations and zinc transporter (ZnT1, ZnT8, and Zip1) gene expression in mononuclear cells were measured. Participants with DM consumed 1,194 ± 824 mg/day (mean ± SD) phytic acid, an amount similar to the intake of healthy women (1,316 ± 708 mg/day). Bread products and breakfast cereals contributed more than 40 % of the phytic acid intake in each group. A positive relationship was observed in all participants between phytic acid and dietary fiber (r = 0.6, P < 0.001) and between dietary fiber and the (calcium)(phytate)/zinc ratio (r = 0.5, P < 0.001). Compared to the healthy group, the messenger RNA ratio of ZnT1 (zinc export) to Zip1 (zinc import) was lower in participants with DM, which may indicate perturbed zinc homeostasis in the disorder. The plasma zinc concentration was not predicted by age, body mass index, health status, zinc bioavailability, or zinc transporter expression. Healthy and diabetic women consume phytic acid in amounts that are likely to decrease the bioavailability of dietary zinc. Recommendations to consume greater amounts of dietary fiber, much of which is associated with phytate, increase the risk of zinc deficiency.

Zinc is an essential nutrient required for numerous metabolic functions. The aim of the present study was to develop a zinc-specific food frequency questionnaire (FFQ) and to determine its relative validity. A 74-item FFQ was designed for the measurement of zinc intake. Food items were included in the FFQ if their zinc content was >0.5 mg/100 g, and the food item contributed >5% of the recommended dietary intake. Female subjects (n = 22) were recruited to complete the questionnaire in addition to maintaining a weighed food record for 7 days. Mean intake of zinc obtained from the weighed records (8.8 +/- 2.3 mg/day; mean +/- SD) was significantly lower than that obtained from the FFQ (10.5 +/- 3.1 mg/day; P < 0.01). Ranked zinc intakes obtained from the two instruments were significantly correlated (r (s) = 0.81, P < 0.001). Evaluation of progressively shortened versions of the FFQ, containing 23-61 food items and representing 60-90% of the contribution to total zinc intake, yielded correspondingly decreasing magnitudes of zinc intake, but the rank correlation with the weighed records was significant (P < 0.01). Rank correlations and analysis of plots from Bland-Altman analyses suggest that a shortened 37-item FFQ has comparable validity to the full FFQ. A shortened FFQ is likely to produce lower demands on the interviewer and/or respondent when assessing zinc intake.

Vitamin B(12) is essential for DNA synthesis and for cellular energy production.This review aims to outline the metabolism of vitamin B(12), and to evaluate the causes and consequences of sub-clinical vitamin B(12) deficiency. Vitamin B(12) deficiency is common, mainly due to limited dietary intake of animal foods or malabsorption of the vitamin. Vegetarians are at risk of vitamin B(12) deficiency as are other groups with low intakes of animal foods or those with restrictive dietary patterns. Malabsorption of vitamin B(12) is most commonly seen in the elderly, secondary to gastric achlorhydria. The symptoms of sub-clinical deficiency are subtle and often not recognized. The long-term consequences of sub-clinical deficiency are not fully known but may include adverse effects on pregnancy outcomes, vascular, cognitive, bone and eye health.

Lipoprotein(a) [Lp(a)] is considered a risk factor for coronary heart disease. Our aim was to investigate the effect of individual fatty acids on postprandial plasma Lp(a) and its association with lipemia and tissue plasminogen activator (t-PA). Five test fats dominated by (approximately 43% g/kg) stearic (S), palmitic (P), oleic, C18:1 trans (T), or linoleic acid were produced by interesterification. Sixteen young healthy men were served the individual test fats incorporated into meals (1g fat/kg body wt) after a 12-h fast in random order on different days, separated by 3-wk washout periods. Blood samples were drawn before and 2, 4, 6, and 8 h after eating. There was a pronounced increase in Lp(a) concentrations after intake of the test meals, and the test fats resulted in a difference in Lp(a) response (P < 0.001; diet x time interaction). However, T fat did not change Lp(a) during the time course studied. T fat resulted in less area under the plasma Lp(a) concentration curve compared to S and P fat (P

Fruit and vegetable consumption is inversely associated with coronary heart disease (CHD) risk. The aim of the present study was to determine the effect of supplementation with dehydrated juice concentrates from mixed fruit and vegetables on selected plasma vitamins and antioxidant status. We assessed CHD risk by measuring the concentrations of homocysteine, lipids, lipoproteins, glucose and insulin. Men were recruited to participate in a randomized double-blind, crossover trial with 2 periods of 6 wk, separated by a 3-wk wash-out period. Supplementation with the encapsulated mixed extract (Juice Plus) was compared with physically similar placebo capsules. Thirty-two men (13 smokers, 19 nonsmokers) completed the study with a mean compliance of 88%. Compared with placebo, supplementation increased the concentrations of plasma beta-carotene (0.24 +/- 0.15 vs. 1.12 +/- 0.70 micro mol/L; mean +/- SD; P < 0.0001), retinol (1.87 +/- 0.33 vs. 2.00 +/- 0.43 micro mol/L; P < 0.05), alpha-tocopherol (16.8 +/- 7.3 vs. 19.3 +/- 6.8 micro mol/L; P < 0.01), ascorbic acid (72.1 +/- 19.4 vs. 84.1 +/- 13.5 micro mol/L; P < 0.002) and folic acid (24.5 +/- 10.0 vs. 44.9 +/- 16.9 nmol/L; P < 0.0001). Plasma homocysteine was reduced (8.2 +/- 1.5 vs. 7.6 +/- 1.1; P < 0.05) and inversely related (r = -0.40, P < 0.001) with serum folate concentrations. Plasma vitamin C was positively correlated with the resistance of LDL to oxidation (r = 0.26, P < 0.05) and the plasma ferric reducing/antioxidant power (FRAP) tended to be greater after supplementation than after the placebo period (1125.5 +/- 144.1 vs. 1180.3 +/- 158.1 micro mol/L; P < 0.065). Plasma glucose, insulin and lipid concentrations were unaffected. Responses of smokers and nonsmokers did not differ. In the absence of dietary modification, supplementation with a fruit and vegetable concentrate produced responses consistent with a reduction in CHD risk.

Background: The consumption of trans fatty acids adversely affects fasting plasma lipoprotein concentrations., Objective: This study aimed to investigate whether postprandial lipoprotein metabolism is affected by the consumption of trans fatty acids., Design: In a randomized crossover study, 19 healthy men consumed fatty meals that were identical except that 10% of energy was provided as trans 18:1 acids in the trans meal and as oleic acid in the cis meal., Results: The meals induced similar responses in plasma lipids. Cholesteryl ester transfer (CET) was activated after consumption of both meals (P < 0.0001); however, it was 28% higher after the trans meal than after the cis meal (280 +/- 129 compared with 219 +/- 116 nmol cholesteryl ester/mL plasma * 6 h; time x diet interaction: P < 0.0001). Plasma apolipoprotein(a) [apo(a)] concentrations remained constant; however, triacylglycerol-rich lipoproteins formed 4 h after ingestion of the trans meal contained a higher concentration of apo(a) than did those formed after ingestion of the cis meal (48.9 +/- 6.6 compared with 39.6 +/- 5.4 U/L; P < 0.02). The change in CET and in the proportion of plasma apo(a) in the triacylglycerol-rich lipoprotein fractions correlated with indexes of alimentary lipemia., Conclusions: Consumption of meals high in trans fatty acids results in higher CET and postprandial lipoprotein concentrations enriched in apo(a) than does consumption of meals free of trans fatty acids. This study highlights the importance of double-bond configuration in determining postprandial lipoprotein composition.

Consumption of isoflavone-rich soyabean protein is reported to reduce total and LDL-cholesterol, but the specific components responsible are undetermined. In a previous crossover trial we showed that purified isoflavones, derived from red clover (Trifolium pratense), raised HDL3-cholesterol in premenopausal women; however, these findings were inconclusive due to period and carryover effects. In an attempt to overcome this problem, we utilised a parallel study designed to re-examine the effects of purified isoflavones on plasma lipoproteins and markers of insulin resistance in premenopausal women. Twenty-five healthy premenopausal women participated in a double-blind, randomised, parallel study. The treatment group (n 12) consumed a placebo for the first menstrual cycle and an isoflavone supplement (86 mg/d, derived from red clover) for three cycles, while the placebo group (n 13) consumed a placebo supplement for four menstrual cycles. Blood samples were collected weekly during cycles 1, 3 and 4. Supplementation with isoflavones resulted in a 15-fold increase in urinary isoflavone excretion (P<0.0001). There were no significant effects on total cholesterol, LDL- and HDL-cholesterol, HDL subfractions, triacylglycerol, lipoprotein(a), glucose or insulin concentrations. Our present results indicate that purified isoflavones derived from red clover have no effect on cholesterol homeostasis or insulin resistance in premenopausal women, a group which is at low risk of CHD.