Dietary phytate x calcium/zinc millimolar ratios and zinc nutriture in some Ontario preschool children.

Millimolar ratios of phytate/Zn, Ca x phytate/Zn, and Ca x phytate/Zn per 4.2 MJ were calculated from 3-d weighed-food records collected from 62 male (M) (mean age: 58 +/- 7 mo [mean +/- SD]) and 44 female (F) (mean age: 58 +/- 6 mo) preschool children from Southern Ontario. Food-composition values for phytate were based on laboratory analysis and the literature. No gender differences existed for median millimolar ratios of phytate/Zn (median: M, 5.3; F, 5.3), and Ca x phytate/Zn per 4.2 MJ (M, 68.1; F, 59.5), but median intakes of phytate (M, 399; F, 333 mg/d) and median millimolar ratios of Ca x phytate/Zn (median: M, 102.1; F, 72.3; p less than 0.01) were higher for boys than for girls. Of the children, only two (1M, 1F) and 22 (17 M, 5F) had millimolar ratios of phytate/Zn and Ca x phytate/Zn per 4.2 MJ, respectively, that were above critical values. Millimolar ratios of Ca x phytate/Zn (p = 0.06) and Ca x phytate/Zn per 4.2 MJ (p = 0.05) were higher in boys with hair zinc less than 1.07 mumol/g v greater than or equal to 1.07 mumol/g. Analysis of variance showed that height was influenced by an interaction between millimolar ratios of Ca x phytate/Zn per 4.2 MJ and sex (p = 0.0007), when age and midparent height were treated as covariates. Results suggest that dietary Ca x phytate/Zn millimolar ratios, when expressed per 4.2 MJ, influenced the zinc nutriture of these Southern Ontario boys.

Seasonal variations in hair zinc concentrations in Canadian and African children.

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.

A growth-limiting, mild zinc-deficiency syndrome in some southern Ontario boys with low height percentiles.

A double-blind, pair-matched 12-mo study examined the effects of a zinc supplement (10 mg Zn/d as ZnSO4) on linear growth, taste acuity, attention span, biochemical indices, and energy intakes of 60 boys (aged 5-7 y) with height less than or equal to 15th and midparent height greater than 25th percentiles. Boys with initial hair Zn less than 1.68 mumol/g (n = 16) had a lower mean (+/- SD) weight-for-age Z score (-0.44 +/- 0.59 vs -0.08 +/- 0.84), and a higher median recognition threshold for salt (15 vs 7.5 mmol; p = 0.02) than those with hair Zn greater than 1.68 mumol/g. Only boys with hair Zn less than 1.68 mumol/g responded to the Zn supplement with a higher mean change in height-for-age Z score (p less than 0.05); taste acuity, energy intakes, and attention span were unaffected. A growth-limiting Zn deficiency syndrome exists in boys with low height percentiles, hair Zn levels less than 1.68 mumol/g, and impaired taste acuity.

Seasonal variations in hair zinc concentrations in Canadian and African children

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

Food consumption patterns of Canadian preschool children in relation to zinc and growth status.

Hair and serum zinc and copper, growth percentiles, and dietary intakes, based on 3-day weighed food records, were determined for 106 Canadian preschool children (62 M, 44 F) aged 4-5 yr. Mean (+/- SD) hair zinc levels were (M) 103 +/- 35 micrograms/g vs (F) 129 +/- 34 micrograms/g, p less than 0.001, and median hair copper level was 12.4 micrograms/g (M + F). Mean serum zinc and copper were 111 +/- 13 micrograms/dL (M + F) and 122 +/- 21 micrograms/dL (M + F), respectively. Males with low hair zinc (less than 70 micrograms/g) had a lower mean height-for-age percentile (42 +/- 29 vs 58 +/- 25%, p less than 0.05), even when adjusted for midparent height. Males with hair zinc less than 70 micrograms/g and/or height-for-age less than 15% consumed less meat, poultry, and fish and received similar average zinc intakes but higher calcium intakes than males with hair zinc greater than or equal to 70 micrograms/g and/or height-for-age greater than or equal to 15%. Suboptimal zinc nutriture was associated with lower intakes of readily available zinc from flesh foods and higher intakes of calcium.