Although vitamins and minerals are commonly used, the health benefits of these supplements are unclear. Most research has looked at the effect of these supplements on immunity and infectious disease, with conflicting results. Barringer and associates used a randomized, double-blind, placebo-controlled trial to assess the subjective effect of vitamin and mineral supplementation on physical and emotional well-being in healthy adults.

A total of 158 participants older than 45 years received a daily oral tablet containing common doses of vitamins and minerals or a control tablet containing calcium, magnesium, and vitamin B₂ for 12 months. All participants completed a stress scale questionnaire and kept a daily food diary. The primary end point was participant-reported infection noted in a daily symptom list kept by all participants as well as a record of infection significance represented by days of missed work or inability to perform planned activities. Quality of life was assessed at baseline and at 12 months using the Medical Outcomes Study 12-Item Short Form.

Seventy-three percent of the participants in the control group had at least one infection-related illness, a rate that was significantly greater than the 43 percent infection rate in the treatment group. Illness-related absenteeism also was significantly greater in the control group. These differences were primarily noted among participants with diabetes. There was no difference in effect on quality of life between the treatment and control groups.

The authors conclude that although there appears to be no improvement in physical and mental health measures or quality of life among healthy users of daily vitamin and mineral supplements, patients with diabetes who may suffer from micronutrient deficiency demonstrate reduced infection frequency. Further testing is necessary to identify additional populations who may benefit from daily vitamin and mineral supplementation.

In an editorial in the same journal, Fawzi and Stampfer point out the specific vitamin supplements that have been demonstrated to prevent chronic disease in certain situations, including folate, vitamin B₁₂, vitamin A, andzinc. Although the data are not definite, they suggest that the potential positive impact of supplements on infection deserves further study, especially among susceptible populations, such as patients with diabetes.