We found no evidence to support antioxidant supplements for primary or secondary prevention. Beta-carotene and vitamin E seem to increase mortality, and so may higher doses of vitamin A. Antioxidant supplements need to be considered as medicinal products and should undergo sufficient evaluation before marketing.
Effect of daily vitamin E and multivitamin-mineral supplementation on acute respiratory tract infections in elderly persons: a randomized controlled trial.
Immune response in elderly individuals has been reported to improve after micronutrient supplementation. However, efficacy trials evaluating infectious diseases as outcomes are scarce and inconclusive.
                To investigate the effect of daily multivitamin-mineral and vitamin E supplementation on incidence and severity of acute respiratory tract infections in elderly individuals.
                A randomized, double blind, placebo-controlled, 2 x 2 factorial trial.
                A total of 652 noninstitutionalized individuals aged 60 years or older enrolled from 2 community-based sampling strategies in the Wageningen area of the Netherlands, conducted from 1998 to 2000. At baseline, 6% of participants had suboptimal ascorbic acid and 1.3% had suboptimal alpha-tocopherol plasma concentration.
                Physiological doses of multivitamin-minerals, 200 mg of vitamin E, both, or placebo.
                Incidence and severity of self-reported acute respiratory tract infections at 15 months, as assessed by a nurse (telephone contact), home visits, and microbiological and serological testing in subsets of patients.
                During a median observation period of 441 days, 443 (68%) of 652 participants recorded 1024 respiratory tract infection episodes. The incidence rate ratio of acute respiratory tract infection for multivitamin-mineral supplementation was 0.95 (95% confidence interval, 0.75-1.15; P =.58) and for vitamin E supplementation, 1.12 (95% confidence interval, 0.88-1.25; P =.21). Severity of infections was not influenced by multivitamin-mineral supplementation. For vitamin E vs no vitamin E, severity was worse: median (interquartile range) for illness-duration was 19 (9-37) vs 14 (6-29) days, P =.02; number of symptoms, 6 (3-8) vs 4 (3-8), P =.03; presence of fever, 36.7% vs 25.2%, P =.009; and restriction of activity, 52.3% vs 41.1%, P =.02.
                Neither daily multivitamin-mineral supplementation at physiological dose nor 200 mg of vitamin E showed a favorable effect on incidence and severity of acute respiratory tract infections in well-nourished noninstitutionalized elderly individuals. Instead we observed adverse effects of vitamin E on illness severity.