Effects of Foods Fortified with Zinc, Alone or Cofortified with Multiple Micronutrients, on Health and Functional Outcomes: A Systematic Review and Meta-Analysis

Abstract

Seventeen per cent of the world's population is estimated to be at risk of inadequate zinc intake, which could in part be addressed by zinc fortification of widely consumed foods. We conducted a review of efficacy and effectiveness studies to ascertain the effect of zinc fortification [postharvest fortification of an industrially produced food or beverage; alone or with multiple micronutrients (MMN)] on a range of health outcomes. Previous reviews have required that the effect of zinc be isolated; because zinc is always cofortified with MMN in existing fortification programs, we did not impose this condition. Outcomes assessed were zinc-related biomarkers (plasma or serum, hair or urine zinc concentrations, comet assay, plasma fatty acid concentrations, and the proportion of and total zinc absorbed in the intestine from the diet), child anthropometry, morbidity, mortality, cognition, plasma or serum iron and copper concentrations, and for observational studies, a change in consumption of the food vehicle. Fifty-nine studies were included in the review; 54 in meta-analyses, totaling 73 comparisons. Zinc fortification with and without MMN increased plasma zinc concentrations (efficacy, n = 27: 4.68 μg/dL; 95% CI: 2.62–6.75; effectiveness, n = 13: 6.28 μg/dL; 95% CI: 5.03–7.77 μg/dL) and reduced the prevalence of zinc deficiency (efficacy, n = 11: OR: 0.76, 95% CI: 0.60–0.96; effectiveness, n = 10: OR: 0.45, 95% CI: 0.31–0.64). There were statistically significant increases in child weight (efficacy, n = 11: 0.43 kg, 95% CI: 0.11–0.75 kg), improvements in short-term auditory memory (efficacy, n = 3: 0.32 point, 95% CI: 0.13–0.50 point), and decreased incidence of diarrhea (efficacy, n = 3: RR: 0.79, 95% CI: 0.68–0.92) and fever (efficacy, n = 2: RR: 0.85, 95% CI: 0.74–0.97). However, these effects cannot be solely attributed to zinc. Our review found that zinc fortification with or without MMN reduced the prevalence of zinc deficiency and may provide health and functional benefits, including a reduced incidence of diarrhea.

The effect of zinc-biofortified rice on zinc status of Bangladeshi preschool children: a randomized, double-masked, household-based, controlled trial

“…A systematic review ( 51 ) concluded that zinc fortification at low levels (between 4 and 10 mg/d) had no significant effect on PZC, whereas zinc supplementation at similar levels increased PZC and reduced the risk of zinc deficiency ( 51 ). In contrast, a recent systematic review concluded that zinc fortification (single or with multiple micronutrients) increases plasma zinc concentrations ( 52 ). In a recent pooled analysis of 3 postharvest zinc-fortified rice studies, the nonsignificant mean between-group difference was 0.38 μmol/L ( 53 ).…”

Zinc Fortification: Current Trends and Strategies

“…However, changes in growth may also be due to changes in energy intake or infections. This contributes to their variability, and these endpoints do not exhibit a clear response to zinc fortification [ 57 , 58 ]. Recently, functional biomarkers of zinc, responsive to the small changes in dietary zinc intake that are typical in zinc fortification, have been identified.…”

“…These data suggest the comet assay may be a promising biomarker for monitoring the effects of zinc fortification. However, no randomized trials have assessed the response of DNA strand breaks to zinc fortification [ 58 ].…”

Unusual Bioactive Compounds with Antioxidant Properties in Adjuvant Therapy Supporting Cognition Impairment in Age-Related Neurodegenerative Disorders

“…Numerous studies have shown the effect of various types of diet on the improvement of cognitive functions [172][173][174][175]. The most frequently mentioned of which are the Mediterranean diet (MD) and the Dietary Approach to Stop Hypertension (DASH) diet, as well as a combination of both nutritional patterns-the MIND diet [174,175].…”