Changes in growth, body composition, and zinc indexes were evaluated after 25 wk in a double-blind zinc-supplementation study of 162 periurban Guatemalan children aged 81.5 +/- 7.0 mo (mean +/- SD). Children receiving the zinc supplement (10 mg Zn/d as amino acid chelate) for 90.1 +/- 9.2 d had higher mean fasting plasma zinc (16.2 +/- 2.9 vs 14.9 +/- 2.1 mumol/L, P < 0.01), a greater increase in median triceps skinfold Z score (0.50 vs 0.38, P < 0.05), and a smaller deficit in median midarm circumference (MAC) Z score (-0.03 vs -0.20, P < 0.05) compared with the placebo group. Initial hair zinc classified as < 1.68 and > 1.68 mumol/g was the only laboratory variable that explained some of the variance in final Z scores of midarm-muscle area (P < 0.05) and MAC (P < 0.01). Children responded to the zinc supplement with changes in indexes of body composition rather than growth.

In a study of periurban Guatemalan school-children (89 males, 73 females) aged 81.5 +/- 7.0 mo (mean +/- SD), height, weight, arm circumference, and triceps-skinfold-thickness (TSF) measurements were examined in relation to plasma and hair zinc concentrations, plasma and red blood cell alkaline phosphatase activities, recognition thresholds for salt (RTS), delayed-cutaneous hypersensitivity response to seven recall skin test antigens, and cognitive measures. Children were stunted [median height-for-age (HA) Z score -1.49] but not wasted [median weight-for-height (WH) Z score 0.20], with median midarm muscle area (MAMA) and midarm-fat area (MAFA) Z scores of -0.57 and -0.35, respectively. Of the children, 63.5% of males and 44.1% of females had hair zinc < 1.68 mumol/g (P < 0.05); 12.3% of males and 1.5% of females had plasma zinc < 10.71 mumol/L (P < 0.05). Children with hair zinc < 1.68 mumol/g had higher (P < 0.05) medians for WA Z and WH Z scores, RTS, and phytic acid intake than did those with hair zinc > or = 1.68 mumol/g. Zinc status explained some of the variance in growth (HA, WA, and WH Z scores), body composition (MAFA Z scores), and taste acuity. Suboptimal zinc status arose partly from diets low in readily available zinc.

After a 1-wk baseline period, a dietary regimen was developed to induce mild zinc deficiency in 15 males (aged 25.3 +/- 3.3 y, mean +/- SD). The regimen consisted of 1 wk on a liquid diet containing 0.6 mg Zn/d and molar ratios of phytate to zinc (phy:Zn) and of phytate X calcium to zinc [(phy X Ca): Zn] of 209 and 4116, respectively, followed by 6 wk on a diet based on soy protein and egg albumin containing 4 mg Zn/d and with phy:Zn and (Ca X phy):Zn of 70 and 2000, respectively. Subjects were then repleted with 30 mg Zn/d for 2 wk. Fasting blood and urine samples were taken weekly. Changes were observed in mean plasma (mumol/L) and urinary zinc (mumol/d): baseline 97.0 +/- 10.9 and 8.0 +/- 2.7, depletion 80.1 +/- 13.4 and 4.3 +/- 2.3, and repletion 100.8 +/- 13.6 and 8.2 +/- 3.1, respectively (P less than 0.05); taste acuity (0.05 less than P less than 0.10); and cellular immune responses (P less than 0.05). Activities of plasma angiotensin-1-converting enzyme and acidic alpha-D-mannosidase were unchanged. Mild zinc deficiency was induced by the dietary regimen.

During a controlled zinc depletion-repletion study, fifteen men aged 25.3 (sd 3.3) years were fed on a low-Zn diet with high phytate:Zn and phytate × calcium: Zn molar ratios for 7 weeks, followed by a 2 week repletion period when 30 mg supplemental Zn/d was given. Changes in plasma, urine, and hair Zn concentrations, taste acuity, and cellular immune response confirmed the development of mild Zn deficiency. Zn concentrations in neutrophils, platelets, erythrocytes and erythrocyte membranes, mean platelet volume, and activities of alkaline phosphatse (EC3.1.3.1) and α-d-mannosidase (EC3.2.1.24) in neutrophils did not respond to changes in Zn status. In contrast, alkaline phosphatase activity in erythrocyte membranes showed a significant decline which was consistent in all subjects (nmol product formed/min per mg protein; baselinev.7-week Zn depletion, 0.656 (sd 0.279)v.0.506 (sd 0.230), at 7 weeks;P< 0.05); neutral phosphatase activity remained unchanged. Alkaline phosphatase activity in erythrocyte membranes may be a potential index of Zn status in humans