Nutrition and Immunity

Many factors can influence how well our immune system works. Immune function tends to decline with age, which can make older people more susceptible to infections. However, mild exercise when performed regularly can stimulate immunity. Nutrition also plays a key role in maintaining a healthy immune response.

Marginal intakes or low body stores of vitamins A, C, E or B6, as well as zinc or selenium have been shown to reduce or impair the body's defense system. Research has also demonstrated that regularly taking a compete vitamin and mineral supplement can support immunity in older individuals.

In one year-long clinical trial, the effects of a multivitamin/mineral supplement were compared with a placebo in healthy men and women sixty-five and older. Significant improvements in immune tests were found only in the group taking the supplement. Most importantly, the supplement group reported less than half the number of infection-related illnesses compared to the placebo group. The number of days antibiotics were used to treat infections was also much lower.

These findings were confirmed in a second study. This double-blind randomized trial, also followed healthy, well-nourished older men and women for a year. Again, the multivitamin/mineral takers experienced nearly two-thirds fewer days of infection-related illness compared to those taking a dummy pill.

Researchers have also looked at the ability of vitamin E to boost immunity in healthy elderly people. Vitamin E (at doses of 60 IU, 200 IU or 800 IU) was found in one trial to significantly improve certain measures of immune function. Fewer infections were also reported, suggesting that vitamin E helped stimulate the immune system to resist infectious disease. The most effective dose in this study was 200 IU, although the optimal level has not been conclusively determined.

References

1. Langseth L et al. Nutrition and Immunity in Man. International Life Sciences Institute Monograph Series, 1999: 1-26.
2. Chandra RK. Effect of vitamin and trace element supplementation on immune responses and infection in elderly subjects. Lancet 1992; 340:1124-27.
3. Spiller G et al. Effects of long term vitamin-mineral supplementation on immune response in older adults. J Am Coll of Nutr 1998; 17:511.
4. Meydani SN et al. Vitamin E supplementation in vivo immune response in healthy elderly subjects: A randomized controlled trial. J Am Med Assoc 1997; 277:1380-6.