The efficacy of micronutrient supplementation in reducing the prevalence of anaemia and deficiencies of zinc and iron among adolescents in Sri Lanka

Abstract

Objective: To determine the effectiveness of combined iron and zinc over the iron or zinc-only supplementation in correcting deficiency and possible interactive effects in a group of adolescent school children. Subjects and methods: Schoolchildren (n ¼ 821) of 12-16 years of age were randomized into four groups and supplemented with iron (50 mg/day), zinc (14 mg/day), iron þ zinc or placebo capsules 5 days per week for 24 weeks. Anthropometry, and haemoglobin (Hb), serum zinc (SZn) and serum ferritin (SF) concentrations were determined before and after the intervention. Results: There were no significant effects between-groups in their weight, height and Hb concentrations with the intervention when compared with the placebo group. Iron-only and combination-supplemented groups had reached mean SF concentrations of 55.1 mg/l with no difference between them (P ¼ 0.99). The zinc-only group had a mean change of 4.3 mmol//l whereas the combine-supplemented group had a mean change of 4.0 mmol/l (P ¼ 0.82). The prevalence of anaemia was found to be 70.3% in the iron group at baseline; this was reduced to 14.5% after the supplementation. In the combinesupplemented group anaemia, prevalence was reduced from 64.8 to 19.3%. Conclusions: Zinc alone or in combination with iron has not shown a significant improvement in growth in adolescence. Severe and moderate forms of anaemia were successfully treated in children who received iron supplementation. Initial high prevalence of low SZn and iron stores was significantly improved with micronutrient supplementation.

Zinc Supplementation in Children Is Not Associated with Decreases in Hemoglobin Concentrations

“…Zinc toxicity (nausea, vomiting) can occur with very high doses, and sideroblastic anemia due to zinc-induced copper deficiency has been documented with doses around 300-600 mg/d in adults (7.5-15 times the tolerable upper intake level) (4). A 13-mo-old child whose daily intake ranged from 120 to 180 mg/d (17)(18)(19)(20)(21)(22)(23)(24)(25)(26) times the upper intake level of 7 mg/d) was also reported to have sideroblastic anemia (5). However, those doses are much higher than doses typically used in supplementation studies (#20 mg/d) and the range of zinc doses presented in this meta-analysis.…”

“…Thus, the pooled estimate of effect is partially based on follow-up values. These values may not represent the true effect of zinc, because there were differences in baseline hemoglobin concentrations between treatment arms in some trials (17,20,26). Second, although the exclusion of 2 outliers did not substantially change the conclusions of the metaanalysis, it is noteworthy that both of these trials were conducted in populations with high rates of zinc deficiency and/or anemia and both suggest a large positive effect of zinc supplementation on hemoglobin concentrations.…”

“…In this model, there was no evidence for influential studies: weights ranged from 0.1 to 7.8%. However, the trials by Olney et al (33) and Hettiarachchi et al (17) were considered as outliers, because their effect sizes were 3-5 times as large as the next largest effect size. After exclusion of those 2 studies from the analysis, the WMD was 20.2 g/L (95% CI: 20.9, 0.5; P = 0.59) and there was no evidence of heterogeneity between studies (I 2 = 0%; P = 0.60).…”

“…Follow-up mean values of hemoglobin and their SD were used for the other 11 studies (15,17,(21)(22)(23)(24)(25)27,29,30) (Table 1). Of those 11 studies, 5 did not report baseline hemoglobin concentrations (15,22,27,29).…”

Linkages of biomarkers of zinc with cognitive performance and taste acuity in adolescent girls

“…These results indicate that the interactions among different micronutrients may have variable effect on the cognition. However, the risk of interactions varies with dose and duration of supplementation and baseline micronutrient status of participants (Hettiarachchi et al, 2008;Sandstrom, 2001). Thus, it is necessary to understand the role of specific nutrients like zinc and interactive effects among multiple micronutrients especially in growing age.…”