Zinc supplementation impairs monocyte function

Abstract

Zinc has been shown to be involved in many functions of the immune system. This study was conducted to examine the effect of zinc supplementation on phagocytic, fungicidal and metabolic activity of blood monocytes of marasmic infants during nutritional rehabilitation. A controlled, double-blind design was used in which 19 infants fed a zinc-fortified formula were compared with 20 infants fed the same, unfortified formula. Evaluation of phagocytic-fungicidal capacity, growth, zinc, copper and iron status was performed in both groups on admission and after 60 and 105 days of nutritional rehabilitation. Although energy, copper and iron intakes were similar in the two groups, a decrease in the number of infants able to phagocytose one or more Candida buds was observed after 60 days of zinc supplementation compared to admission (p < 0.03). No change in phagocytic ability was detected between admission and 60 days in the control group. The number of infants with depressed fungicidal activity increased significantly after 105 days of nutritional rehabilitation in the zinc-fortified group as compared to controls (p < 0.04). The number and duration of impetigo episodes was significantly greater in the group fed the zinc-fortified formula. These results suggest that zinc supplements at the RDA level may impair monocyte function.

Possibilities for zinc in the treatment of acute diarrhea

“…Although the dose used in the Chandra study (5) might seem unrealistically excessive, this dose translates into Ϸ4 mg elemental Zn/kg for a 70-kg adult, not too unlike the nearly 3 mg/kg of the 20-mg dose in a 7-kg, 7-mo-old infant. Depressed fungicidal activity consistent with impaired monocyte function as well as increased incidence and duration of impetigo was observed in infants consuming a formula delivering 1.9 mg elemental Zn · kg Ϫ1 · d Ϫ1 compared with control infants consuming 0.35 mg Zn · kg Ϫ1 · d Ϫ1 (10). Just as it is required for most pharmacologic agents used in pediatric medicine, a dose adjusted for body weight might be necessary to ensure the efficacious and safe therapeutic use of zinc in the treatment of acute infectious diarrhea.…”

An overview of interactions between micronutrients and of micronutrients with drugs, genes and immune mechanisms

“…Depressed immune responses were observed in another study where patients were given 100-300 mg/d (Chandra, 1984). Likewise, the phagocytic and fungicidal activity of monocytes was impaired, and the duration of episodes of impetigo was increased in a group of marasmic infants who were given a Zn-fortified formula in a double-blind controlled trial (Schlesinger et al 1993). The results were seen between 60 and 150 d of Zn supplementation and suggest that Zn supplements even at the recommended dietary allowance level may impair monocyte function.…”

A systems biology approach to nutritional immunology – Focus on innate immunity

“…Zinc is critical to innate immune cell development and activity, and zinc-deficient conditions impair macrophage phagocytosis and intracellular killing (Sheikh et al, 2010;Wirth et al, 1989). Zinc supplementation in malnourished children and children with Escherichia coliinduced diarrhea resulted in reduced phagocytic and fungicidal activity and oxidative burst (Schlesinger et al, 1993;Sheikh et al, 2010). Conversely, high zinc concentrations have been reported to suppress macrophage chemotaxis, activation, phagocytosis and oxidative burst in vitro (Allen et al, 1983;Chvapil et al, 1977;Karl et al, 1973).…”