The global burden of high fasting plasma glucose associated with zinc deficiency: Results of a systematic review and meta-analysis

Effects of Zinc-Biofortified Wheat Intake on Plasma Markers of Fatty Acid Metabolism and Oxidative Stress Among Adolescents

BACKGROUND/OBJECTIVE

Zinc deficiency is common worldwide and has been linked to reduced growth and immune function, increased risk of and slower recovery from infections, and increased risk of non-communicable diseases. To address the issue, zinc biofortification of wheat has been proposed as a sustainable approach to increase dietary zinc intake in countries like Pakistan, where zinc deficiency rates are high and wheat is the primary staple crop. Since plasma zinc concentration (PZC) does not reliably respond to small changes in zinc intake, biomarkers sensitive to small changes in zinc intake achievable though biofortification are needed. Activity indices for zinc-dependent metabolic steps of desaturation and elongation of omega-6 fatty acids (FAs) have been proposed as sensitive zinc biomarkers. Oxylipin metabolites of polyunsaturated FAs may also respond to changes in zinc intake and further mediate metabolic response to oxidative stress. The objective of the current study was to assess the effects of consuming zinc-biofortified wheat flour on plasma markers of fatty acid (FA) metabolism in females aged 10-16 years.

METHODS

A nested secondary analysis was conducted in samples from a double-blind, cluster-randomized controlled trial conducted in rural Pakistan, whereparticipants (n = 517) consumed either zinc-biofortified wheat flour or control flour for 25 weeks. Total plasma FAs and oxylipins were measured by liquid chromatography tandem mass spectrometry (LC-MS/MS). Activity indices were estimated from the ratios of product to precursor FAs.

RESULTS

Except for docosahexaenoic acid (DHA, p < 0.05), no significant intervention effect was observed on plasma FAs and FA activity index endpoints. Zinc-biofortified wheat intake reduced pro-inflammatory oxylipins and biomarkers of oxidative stress, 5-HETE (p < 0.05), 9-HETE (p < 0.05), 11-HETE (p < 0.05), and 15-HETE (p < 0.05), compared with the control. However, after adjustment for multiple comparisons, none of the intervention effects remained significant.

CONCLUSIONS

Further study of the responsiveness and specificity of plasma oxylipins to changes in zinc intake is warranted.

Preventing and Controlling Zinc Deficiency Across the Life Course: A Call to Action

Through diverse roles, zinc determines a greater number of critical life functions than any other single micronutrient. Beyond the well-recognized importance of zinc for child growth and resistance to infections, zinc has numerous specific roles covering the regulation of glucose metabolism, and growing evidence links zinc deficiency with increased risk of diabetes and cardiometabolic disorders. Zinc nutriture is, thus, vitally important to health across the life course. Zinc deficiency is also one of the most common forms of micronutrient malnutrition globally. A clearer estimate of the burden of health disparity attributable to zinc deficiency in adulthood and later life emerges when accounting for its contribution to global elevated fasting blood glucose and related noncommunicable diseases (NCDs). Yet progress attenuating its prevalence has been limited due, in part, to the lack of sensitive and specific methods to assess human zinc status. This narrative review covers recent developments in our understanding of zinc's role in health, the impact of the changing climate and global context on zinc intake, novel functional biomarkers showing promise for monitoring population-level interventions, and solutions for improving population zinc intake. It aims to spur on implementation of evidence-based interventions for preventing and controlling zinc deficiency across the life course. Increasing zinc intake and combating global zinc deficiency requires context-specific strategies and a combination of complementary, evidence-based interventions, including supplementation, food fortification, and food and agricultural solutions such as biofortification, alongside efforts to improve zinc bioavailability. Enhancing dietary zinc content and bioavailability through zinc biofortification is an inclusive nutrition solution that can benefit the most vulnerable individuals and populations affected by inadequate diets to the greatest extent.

Zinc supplementation and cardiovascular disease risk factors: A GRADE-assessed systematic review and dose-response meta-analysis

BACKGROUND AND OBJECTIVE

A deficit in zinc has been related to a higher probability of developing cardiovascular diseases (CVDs). The anti-inflammatory and anti-oxidative capabilities of zinc may have a wide range of therapeutic impacts on CVDs. We conducted a comprehensive systematic review and meta-analysis of the possible impacts that zinc supplementation may have on the risk factors associated with CVDs.

METHODS

To identify eligible randomized clinical trials (RCTs) evaluating the effects of zinc supplementation on CVDs risk factors, electronic databases including PubMed, Web of Science, and Scopus were systematically searched up to January 2023. The heterogeneity of trials was checked using the I² statistic. According to the heterogeneity tests, random effects models were estimated and pooled data were defined as the weighted mean difference (WMD) with a 95% confidence interval (CI).

RESULTS

Of 23165 initial records, 75 studies that met inclusion criteria were analyzed in this meta-analysis. The pooled findings indicated the significant lowering effects of zinc supplementation on triglycerides (TG), total cholesterol (TC), fasting blood glucose (FBG), Hemoglobin A1C (HbA1C), Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), C-reactive protein (CRP), interleukin-6 (IL-6), Tumor necrosis factor-α (TNF-α), nitric oxide (NO), malondialdehyde (MDA), total antioxidant capacity (TAC), and glutathione (GSH), with no noticeable effects on low-density lipoprotein (LDL), high-density lipoprotein (HDL), insulin, systolic blood pressure (SBP), diastolic blood pressure (DBP), aspartate transaminase (AST), and Alanine aminotransferase (ALT).

CONCLUSION

Overall, zinc supplementation may boost recognized coronary risk factors that contribute to the development of CVDs. Future research should be conducted to bolster our results.