Aug. 8, 2005 -- Multivitamin and multimineral supplementation does not affect morbidity, according to the results of a randomized, double-blind study published in the Aug. 6 issue of the British Medical Journal.

"At least 25% of older people in the United Kingdom take nutritional supplements," write Alison Avenell, from the University of Aberdeen, United Kingdom, and colleagues from the Writing Group of the Mineral and Vitamin Intervention Study (MAVIS). "Multivitamin and multimineral supplements are widely available and most brands have similar contents. Whether such supplementation influences infections in older people, particularly those not in nursing homes, is unclear from randomized controlled trials."

In communities associated with six general practices in Grampian, Scotland, 910 men and women age 65 years or older who did not take vitamins or minerals were randomized to receive either daily multivitamin and multimineral supplementation or placebo for one year. The primary endpoints were primary care contacts for infections, self-reported days with infection, and quality of life, and secondary outcomes included antibiotic prescriptions, hospital admissions, adverse events, and compliance.

Supplementation did not significantly affect primary care contacts and days of infection per person (incidence rate ratios, 0.96 [95% confidence interval {CI}, 0.78 - 1.19] and 1.07 [95% CI, 0.90 - 1.27], respectively). The groups did not differ significantly in quality of life or in any secondary outcomes, either overall or in subgroups.

"Routine multivitamin and multimineral supplementation of older people living at home does not affect self-reported infection-related morbidity," the authors write.

Study limitations include few subjects age 85 years or older or in nursing homes, who may be at higher risk of nutritional deficiency; possibly healthier study subjects than people who did not volunteer for the study; exclusion of people already taking nutritional supplements; inability to exclude the possibility that the intakes provided in the supplement were insufficient to affect the immune system; and use of self-report to establish infections.

Health Foundation (formerly PPP Healthcare Medical Trust) funded this study. The authors report no competing interests.

In an accompanying editorial, Salah Gariballa, from the University of Sheffield, Northern General Hospital in Sheffield, United Kingdom, suggests that vitamin and mineral supplements may help prevent infections in some older people but that improved diet and physical activity are more beneficial.

She notes that this was a robust study overall but that limitations may include confounding and measurement biases, lack of data on dietary intake or physical activity, low doses of multivitamins and minerals used, and the relatively healthy study population.

"Supplements of vitamins and minerals might still benefit older people with increased risk of infections and those with evidence of vitamin deficiencies, Dr. Gariballa writes. But we will not know for sure until further robust studies have been done among high risk groups, including those with poor immunity and those living in institutional care."

Dr. Gariballa reports no financial conflicts of interest.

BMJ. 2005;331:304-305, 324-327