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Inadequate nutriture of zinc, copper and iron alter immunocompetence in humans and experimental animals. For each of these minerals deficient status leads to increased susceptibility to infectious illnesses. Specific components of the immune response may be altered in a variety of patients and models. Although many generalized functions for these nutrients could lead to altered immune function, specific functions for these minerals in immunity have not yet been identified. For zinc, copper and iron the importance of adequate nutrition in maintaining immunocompetency cannot be understated.

Natural killer (NK) cell activity is impaired in iron-deficient rats. Natural killer cells destroy tumor cells; therefore, iron-deficient rats may be less able to combat cancer growth. Natural killer cell cytotoxicity, both basal and interferon gamma (IFN gamma)-stimulated, was studied in moderately and severely iron-deficient rats challenged with the carcinogen 7,12-dimethylbenz[a]anthracene (DMBA). Female weanling rats were fed ad libitum semipurified diets containing 8, 13 or 42 mg Fe/kg. A pair-fed group was fed the 42 mg Fe/kg diet at the level consumed by the 8 mg Fe/kg group. Following 6 wk of dietary treatment, DMBA-treated rats received a single intragastric dose of DMBA. Dietary treatment was continued. Rats were killed at 1, 4, 8, 14 and 20 wk post-DMBA treatment. Natural killer cell cytotoxicity (both basal and IFN gamma-stimulated) was analyzed. Feeding the 13 mg Fe/kg diet resulted in lower NK cell activity (P = 0.006) and greater tumor burden (P = 0.045) and tumor incidence. Interferon gamma treatment relieved the lower NK cell cytotoxicity observed in moderate iron deficiency. Feeding the 8 mg Fe/kg diet impaired NK cell activity (P = 0.006), but tumor burden and incidence were less than in moderate iron deficiency. In this model, iron deficiency, particularly moderate iron deficiency, contributed to cancer development and compromised NK cell cytotoxicity.

No abstract

We studied parameters of iron and copper status in male and female weanling rats that swan 1 1/2 hours per day, 5 days per week or were sedentary for 9 weeks. Final body weights of exercised males were lower (P less than 0.005) than sedentary males, although food intakes were comparable. Blood hemoglobin concentrations and hematocrit levels were increased in the exercising males compared to the sedentary males (P less than 0.025). Serum ceruloplasmin levels were significantly elevated in the exercised group. There was a trend toward decreased iron and increased copper in the spleens, livers and hearts of the exercised males. Total fecal iron was increased and, therefore, apparent iron absorption was decreased in the male exercise group as calculated from an iron and copper balance study conducted during week 8 of the exercise period. In female rats there were no effects of exercise in the parameters measured. Whether the different responses of males and females are due to sexual differences or a relative lack of exercise in the female rats which floated easily is not known. Elevated ceruloplasmin levels may be related to the stress of exercise. The results of this study indicate that exercise produces an alteration in iron and copper distribution and/or iron reutilization, absorption or excretion.