Will a Vitamin a Day Keep the Doctor Away?

A June 20, 2002 press release from the Council for Responsible Nutrition (CRN) proclaimed: “Harvard Researchers Publish JAMA [Journal of the American Medical Association] Articles Recommending Vitamin Supplements For All Adults.” The studies concerned vitamins for chronic disease prevention. The press quoted the authors of the studies saying “we recommend that all adults take one multivitamin daily.” This research was published in the June 19, 2002 issue of JAMA.

CRN is one of the dietary supplement industry’s leading lobbying groups and operates under a thin veneer of scientific rigor. Their credo: if you don’t have it (scientific evidence), advertise that you do; it’s cheaper.

Only two months later, on August 14, 2002, JAMA published research on the effect of daily multivitamin-mineral and vitamin E use on acute respiratory tract infections in the elderly. This study concluded that neither daily multivitamin-mineral use nor 200 milligrams of vitamin E showed a beneficial effect on the incidence and severity of acute respiratory tract infections in well-nourished noninstitutionalized elderly persons. In fact, these researchers observed adverse effects of vitamin E on the severity of illness.

CRN did not issue a press release about the results of this most recent JAMA publication. More vitamins are sold if the negatives are not mentioned.

In their June 20th press release CRN was selective in their praise of vitamins. There were several observations made by the authors of the June 19th JAMA studies that add important context to the debate about the benefits of vitamins not highlighted by CRN:

The science of vitamin supplementation for chronic disease prevention is not well developed, and much of the evidence come from observational studies.

The JAMA authors went on to say:

Foods contain thousands of compounds that may be biologically active, including hundreds of natural antioxidants, caro-tenoids, and flavonoids. For these reasons, vitamin supplementation is not an adequate substitute for a good diet (emphasis added).

Why are there such conflicting results between the June and August studies?

First, the June study addressed vitamins for chronic disease prevention in adults and the August publication was about the effect of vitamins on the development of acute respiratory tract infections in the elderly. These are two very different situations.

Second, the June study was a review of the published literature, a type of summary of studies, while the August study was an experiment, the scientific gold standard, a randomized controlled trial. Literature reviews are important and useful, but one of their most important uses is to develop research questions that ultimately must be tested using a randomized controlled trial.

It is too soon to forget the lesson of hormone replacement therapy (HRT). Studies other than randomized controlled trials were the basis for prescribing HRT to millions of women to prevent cardiovascular disease. When a randomized controlled trial of HRT was undertaken it was stopped early because of increases in breast cancer, cardiovascular disease, stroke, and blood clots that were found in the women using HRT (see the September 2002 issue of Worst Pills, Best Pills News).

Third, literature reviews are prone to a type of bias that can incorrectly lead to a conclusion that a particular treatment or behavior such as taking vitamins is beneficial. This is known as publication bias and occurs because journal editors are more likely to publish favorable studies than those that are unfavorable. Also, because so much research is currently being sponsored and controlled by companies that are selling the treatment, only those studies that reflect favorably on the product may even be submitted for publication.

The June literature review looked primarily at vegans (strict vegetarians), alcohol dependent individuals, patients with malabsorption problems and the elderly. The review concluded that inadequate intake of several vitamins is linked to, but does not cause, some chronic disease in these groups of patients, if the elderly are malnourished. This is not unreasonable.

Turning to the August randomized, controlled trial. This trial was conducted in the Netherlands and involved 652 individuals aged 60 years or older most of whom lived at home. They were randomly assigned to four groups: 1) multivitamin-mineral, 2) vitamin E alone, 3) multivitamin plus vitamin E, and 4) a dummy placebo. The 652 individuals were followed for a maximum of 15 months and kept track of the number and severity of acute respiratory tract infections under the supervision of a nurse.

The multivitamin-mineral group had 240 episodes of acute infections with 71 percent experiencing at least one episode; the vitamin E alone group developed 280 episodes of infection among 68 percent; the multivitamin-mineral plus vitamin E group experienced 274 infections among 66 percent; and the placebo group had 230 infections among 67 percent of the individuals.

The number and severity of acute respiratory tract infections were not lowered in those taking multivitamin-minerals alone or with vitamin E. However, among those receiving vitamin E alone and experiencing an infection, the duration of illness and the total number of symptoms were significantly higher, and fever and restriction of activity occurred more frequently, than those in the no-vitamin groups.

The results of this study have important personal and public health implications. The elderly may be worse off with vitamin E supplementation than without it and the health care system may be unnecessarily being burdened because of vitamin E supplementation.

The authors concluded:

If our results are confirmed and vitamin E exacerbates respiratory tract infections, elderly people, especially those who are already well-nourished, should be cautious about taking vitamin E supplements.

The researchers give the always appropriate scientific response—confirmation of their results is needed and a recommendation of being cautious. A clearer recommendation would be more appropriate. As the authors noted, the only previous studies of vitamin E supplementation in these types of patients did not focus on infectious diseases and no published research could be found on vitamin E supplementation and the severity of respiratory tract infections. It is no longer possible to say, I’ll take vitamin E, it might help but it won’t harm. The weight of the evidence is, for now, for the use of vitamin E described in the study, more harm than benefit will result.

Will a vitamin a day keep the doctor away? If you are malnourished or a strict vegetarian trying to prevent chronic disease due to a vitamin deficiency maybe, but there is also the possibility of harm. If you are a well-nourished elderly person living at home, taking vitamin E may actually increase the number of times you must see your doctor.

What You Can Do

Your best bet for a long and healthy life is a good diet and exercise. This is also less expensive than buying a lot of costly vitamins.