Do low-phytate maize or zinc supplements enhance growth?

May 2010

An article published in the May 2010 issue of The Journal of Nutrition presents the results of a trial that measured the effect of giving low-phytate maize, zinc supplements, or both on linear growth velocity among infants aged 6 to 12 months in Guatemala. Stunting prevalence is high in this population, and zinc deficiency—resulting from low zinc intake and the absorption-reducing effects of high-phytate diets—is a suspected cause. Maize tends to be high in phytic acid, which inhibits zinc absorption. Infants were first randomized to receive either ‘control’ maize or low-phytate maize, and then randomized to receive either 5-mg zinc tablets or placebo daily. Infants who received zinc had higher serum zinc concentrations, but that did not translate to better growth. The authors suggested that the lack of an effect from low-phytate maize may be due to relatively low maize consumption in this age group, and especially due to low zinc intake from complementary foods such that total zinc intake may have been too low to demonstrate an effect of using low-phytate maize. The lack of an impact on child growth—despite higher-plasma zinc concentration—underscores the need to improve scientific understanding of the relationship between zinc and growth. Most notable, the authors say, is the high rate of stunting at an early age in this population, for which scientists, to date, have no conclusive explanation.

Neither a Zinc Supplement nor Phytate-Reduced Maize nor Their Combination Enhance Growth of 6- to 12-Month-Old Guatemalan Infants