Effects of one year of supplementation with zinc and other micronutrients on cellular immunity in the elderly.

The objective of this study was to determine the effects of a year of Zn supplementation on Zn concentrations in circulating cells and on cellular immune functions in the elderly. Subjects, aged 60-89, were given a placebo, 15 mg Zn, or 100 mg Zn daily for 12 months. All subjects also received a multivitamin/mineral supplement that contained no additional Zn. Blood samples were drawn and immune functions assessed prior to and at 3, 6, 12, and 16 months after beginning Zn supplementation. Subject diets were also assessed at each visit. Dietary folate, pyridoxine, alpha-tocopherol, copper, zinc, and magnesium were consistently below recommended intakes. Although plasma Zn increased significantly in the 100 mg Zn treatment group, concentrations of Zn in erythrocytes, mononuclear cells, polymorphonuclear leukocytes, and platelets were not significantly increased by zinc supplementation. Natural killer cell activity was transiently enhanced by the 100 mg/day dose of Zn. There was a progressive improvement in delayed dermal hypersensitivity (DDH) and in lymphocyte proliferative responses to two mitogens; this may have been due to one or more components of the multivitamin/mineral supplement administered to all study subjects. The enhancement of DDH was significantly greater in the placebo group than in either zinc treatment group. Thus, zinc had a beneficial effect on one measure of cellular immune function while simultaneously having an adverse effect on another measure of cellular immunity.

Zinc and immunocompetence in elderly people: effects of zinc supplementation for 3 months.

One hundred and three apparently healthy elderly subjects age 60-89 y were randomly assigned to one of three treatments: placebo, 15 mg zinc/d, or 100 mg Zn/d for 3 mo. Plasma Zn was significantly increased only in the 100 mg Zn group. Zn concentrations in erythrocytes, platelets, mononuclear cells, and polymorphonuclear leukocytes were not significantly increased by any treatment. None of the treatments significantly altered delayed dermal hypersensitivity (DDH) to a panel of seven recall antigens or in vitro lymphocyte proliferative responses (LPR) to mitogens and antigens. Fifteen subjects had initially poor lymphocyte proliferative responses that improved in 14 of these individuals during the study; this was not due to Zn supplementation but might have been caused by one or more components of a vitamin-mineral supplement administered to all study subjects.

Zinc and immunocompetence in the elderly: baseline data on zinc nutriture and immunity in unsupplemented subjects.

Zinc nutriture and immune function were studied in 100 subjects, age 60-89 yr. Mean (+/- SD) zinc concentrations found were 84.8 +/- 15.5 micrograms/dL (13.0 +/- 2.4 microM) for plasma, 1.04 +/- 0.24 micrograms (0.016 +/- 0.004 mumol)/10(9) cells for erythrocytes, 4.06 +/- 1.85 micrograms (0.062 +/- 0.028 mumol)/10(9) cells for mononuclear cells, 3.91 +/- 1.77 micrograms (0.060 +/- 0.027 mumol)/10(9) cells for polymorphonuclear leukocytes, 0.53 +/- 0.39 micrograms (0.0081 +/- 0.0060 mumol)/10(9) cells for platelets, and 222 +/- 101 micrograms (3.39 +/- 1.54 mumol)/g for hair. Zinc ingestion was below the RDA in more than 90% of study subjects. The incidence of anergy to a panel of seven skin test antigens was 41%; responses to these antigens were significantly associated with the plasma zinc concentration. Subjects with depressed lymphocyte responses to mitogens had significantly lower platelet and significantly higher mononuclear cell zinc concentrations than those with normal responses.