ZINC SUPPLEMENTATION AFFECTS THE ACTIVITY PATTERNS OF RURAL GUATEMALAN INFANTS

Zinc deficiency has been associated with growth deficits, reduced diet ary intake and appetite, and has been hypothesized to result in reduce d activity. This randomized, double-blind, placebo-controlled study ex amined whether 10 mg of oral zinc as zinc sulfate, given daily for up to 7 mo, affected activity patterns of 85 Guatemalan infants recruited at 6-9 mo of age. Infant activity was assessed by time sampling-obser vation method at 10-min intervals during a 12-h data collection period , at base line, 3 and 7 mo follow-up. Motor development and the percen tage of time infants were observed in various positions (being carried , lying down, sitting, crawling, standing or walking) and engaged in v arious activities (eating, sleeping, resting, crying/whining or playin g) were compared by treatment group. No differences in motor developme nt were observed by treatment group. However, at follow-up 2 (after 7 mo of supplementation), zinc-supplemented infants were significantly m ore frequently observed sitting up compared with lying down, and were playing during 4.18 +/- 1.95% (P < 0.05) more observations than unsupp lemented infants. They were also somewhat less likely to be observed c rying or whining (P < 0.10) compared with those receiving the placebo. These effects are independent of other factors including infant age, motor development, sex, maternal education, family socioeconomic statu s and nutritional status at base line. Further research must be conduc ted to determine the long-term developmental importance of these diffe rences in activity patterns associated with zinc supplementation in th is setting.