ABSTRACT
Proximal occipital scalp hair samples were collected during three survey periods from 30 omniverous Canadian boys aged 75.6 +/- 10.4 months (mean +/- SD) and 66 rural Malawian children (37 M; 29 F) aged 62 +/- 10 months (mean +/- SD) consuming predominantly plant-based diets. Hair samples were washed and then analyzed for zinc and copper using instrumental neutron activation analysis. Selected anthropometric measurements were also taken and dietary intakes calculated from weighed dietary records. A marked seasonal variation in hair zinc concentrations occurred in both groups; levels were highest in the season with shortest daylight hours (i.e. December /January in Canada vs July/August in Malawi). A similar trend was not observed for hair copper concentrations. Changes in hair zinc were not associated with changes in growth indices; age; socio-economic group; method of infant feeding; in either group; but were related to intakes of protein (per 1000 kcal) (p = 0.02; r = -0.36); zinc (mg day-1) (p = 0.01; r = -0.39); and dietary fiber (g day-1) (p = 0.04; r = 0.28); in the Malawian children during the second survey period. The seasonal effect on hair zinc concentrations must always be considered when interpreting hair zinc concentrations in children; its etiology remains unclear
ABSTRACT
Dietary zinc; calcium; and phytate intakes of 66 rural Malawian children aged 4-6 y were determined during three seasons on the basis of weighed food records and analyzed food composition data. Height and weight measurements were also recorded and hair samples were collected for zinc analysis. Seasonal daily zinc; calcium; and phytate intakes of females ranged from 6.2 +/- 1.7 to 6.8 +/- 2.1 mg (mean +/- SD); from 335 +/- 170 to 401 +/- 257 mg; and from 1621 +/- 660 to 1729 +/- 592 mg; respectively and; for males; 7.0 +/- 1.7 to 8.0 +/- 2.3 mg; 342 +/- 164 to 473 +/- 310 mg; and 1857 +/- 530 to 2161 +/- 684 mg; respectively. Cereals provided greater than 42 percent of dietary zinc. Seasonal mean molar ratios of phytate to Zn and Ca x phytate to Zn (per 1000 kcal (4.2 MJ)) and the median Ca to phytate molar ratio ranged from 24 to 27; 151 to 188 mmol/1000 kcal (4.2 MJ); and 3.1 to 3.4; respectively. Over 78 percent of the children consumed diets with phytate-to-Zn and Ca x phytate.Zn-1 . 1000 kcal-1 molar ratios above values suggested to jeopardize zinc status. Correlations between hair zinc; phytate-to-Zn; and Ca x phytate.Zn-1 . 1000 kcal-1 molar ratios suggest that high phytic acid intakes may compromise zinc status in these children