Research: SANTOS and colleagues, Je

Listed in Issue 31

Abstract

SANTOS and colleagues, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston MA 02111 USA write that providing healthy elderly people with dietary supplements of beta-carotene has been considered a method to enhance their immune response . The authors studied the effects of beta-carotene upon immunity.

Background

Methodology

The authors conducted a randomised, double-blind, placebo-controlled longitudinal comparison of healthy elderly women to study the short-term effects of beta-carotene (90mg/day) upon immunity for 3 weeks (Study 1). The authors conducted a second study, a randomised, double-blind, placebo-controlled longitudinal comparison of men enrolled in the Physicians Health Study (Study 2) to assess the long-term effect of beta-carotene (50 mg every other day for 10-12 years).

Results

The participants in both studies who took the beta-carotene supplements showed significantly greater concentrations of plasma beta-carotene than those in the placebo group. In neither the short-term or long-term studies, the pre- to post-intervention change in delayed-type hypersensitivity skin test responses between the beta-carotene and placebo groups was not significantly different. There were no significant differences seen upon in vitro lymphocyte proliferation, production of interleukin-2 or prostaglandin E2 in either the short- or long-term supplementation groups. There were no differences in profiles of lymphocyte subsets (total T cells (CD3+), T-helper cells (CD4+), T cytotoxic-suppressor cells (CD8+) and B cells (CD19+), nor differences in percentages of CD16+ natural killer cells or activated lymphocytes (cells expressing interleukin 2 transferrin receptor) in the long-term supplemented group.

Conclusion

The results from these two trials showed that supplementation with beta-carotene did not enhance or suppress T cell-mediated immunity in healthy elderly people.

References

Santos MS et al. Short- and long-term beta-carotene supplementation do not influence T cell-mediated immunity in healthy elderly persons. Am J Clin Nutr 66 (4): 917-24. Oct 1997.

Comment

What is now required would be parallel short and long-term studies investigating the effects of beta-carotene upon immunity in elderly people who were not healthy. One would imagine that an effect could be seen where deficiencies exist.

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