Clinical Briefs: Multivitamins and Type 2 Diabetes

With Comments from Russell H. Greenfield, MD

Source: Barringer TA, et al. Effect of a multivitamin and mineral supplement on infection and quality of life. Ann Intern Med 2003; 138:365-371.

Goal: To investigate whether the use of a multivitamin and mineral supplement has a significant clinical impact on well-being and incidence of infection.

Design: Randomized, double-blind, placebo-controlled study.

Subjects: One hundred fifty-eight subjects older than age 45 who had not used a multivitamin and mineral supplement during the previous month were recruited from two academic primary care clinics (130 available for final analysis).

Methods: Subjects were randomized to receive either placebo or a suitably representative multivitamin and mineral supplement to be taken every day for one year. Subjects were to maintain a daily diary tracking infections and sick days, the contents of which were reviewed at each quarterly visit. Evaluable data included self-reported symptoms of infection, infection-associated absenteeism, and quality of life using results from completed Medical Outcomes Study 12-Item Short Forms. Subjects were stratified by age (45-64, and ³ 65 years) and presence of Type 2 diabetes.

Results: Only 43% of those people using a multivitamin reported an infectious illness, while 73% of those taking the placebo experienced an infection. Illness-related absenteeism was higher in the placebo group. Of note, however, is that subjects with Type 2 diabetes accounted for the majority of positive findings, with only 17% of those taking a multivitamin reporting an infection compared to 93% in the placebo group. Not one diabetic subject receiving a multivitamin missed work due to infection, compared with 89% of those in the placebo group. Healthy individuals experienced no significant benefit from use of the supplement. No differences in quality of life were detected per short form responses.

Conclusion: Perhaps due to correction of underlying micronutrient deficiencies, the use of a multivitamin and mineral supplement appears to decrease the incidence of infection in Type 2 diabetics.

Study strengths: Overall design; statistical analysis; efforts to make the placebo and multivitamin indistinguishable from one another.

Study weaknesses: Overall low incidence of infection (54/130 subjects reported no infections over the course of a year); significant dropout rate (likely due to duration of study and daily diary requirement); relatively small sample size with all patients older than age 45, and only a small number older than age 65, limiting generalizability; difficult to gauge compliance with heavy reliance upon self-reporting.

Of note: Subjects with diabetes were more likely to be indigent, obese, less-educated, and poorly nourished than those without diabetes.

Did you know? The normal immune response can be significantly impaired in the presence of even mild nutritional deficiencies.

Clinical import: This well-done trial strongly suggests that patients older than age 45 with Type 2 diabetes benefit (decreased infection rate) from using a daily multivitamin and mineral supplement.

What to do with this article: Keep a hard copy in your file cabinet.

Dr. Greenfield is Medical Director, Carolinas Integrative Health, Carolinas HealthCare System, Charlotte, NC.