Americans spend about $10 billion each year on vitamin and mineral supplements.

Are we spending our money wisely? Or, as the Guardian newspaper put it, are we just “flushing our money down the toilet”?

It’s looking more and more like the latter. At least, for most of us. As reported in an article in the February issue of the newsletter Consumer Reports on Health (now available online at the Consumers Union website), “recent studies undertaken to assess [the benefits of vitamin and mineral supplements] have delivered a flurry of disappointing results. The supplements failed to prevent Alzheimer’s disease, cancer, heart attacks, strokes, Type 2 diabetes and premature death.”

While some people may need supplements at certain stages of their lives, nutritional deficiencies are uncommon in the United States. Major health organizations for cancer, diabetes and heart disease all advise against supplements in favor of a healthful diet rich in fruits, vegetables, whole grains and legumes. Unlike pills, those foods contain fiber plus thousands of health-protective substances that seem to work together more powerfully than any single ingredient can work alone.

Another concern is that some vitamin pills can be toxic if taken in high doses for a long time. Studies show that beta carotene pills can be toxic if taken in high doses for a long time. Studies show that beta carotene pills, for example, can increase the risk of lung cancer in smokers, and a 2008 review suggests that the pills, plus supplemental doses of the vitamins A and E, may increase the risk of premature death. Yet despite such unfavorable results, vitamin and mineral pills are widely used to fend off disease.

The article goes on to briefly summarize the recent studies that have failed to find evidence to support the use of supplements for preventing cancer, heart disease, type 2 diabetes and cognitive decline, or for strengthening the immune system. The article does note that there’s some evidence to support the use of supplements by people with moderate age-related macular degeneration and osteoporosis, although in the latter case, the supplements (calcium and vitamin D) were found to prevent fractures primarily in women living in nursing homes.

(Consumers Union provides a chart that explains "When a supplement might make sense" and a discussion of "Who really needs a multi?")

Right now, Vitamin D seems to be the supplement du jour. As I reported in MinnPost a couple of years ago (and which remains true today), hardly a week goes by when I don’t receive some kind of press release stating Vitamin D deficiencies have been linked to this or that medical condition.

But, as JoAnn E. Manson, MD, chief of preventive medicine at Brigham and Women’s Hospital in Boston and an investigator on several Harvard University vitamin studies, told the New York Times last fall: “Vitamin D looks really promising. But we need to learn the lessons from the past. We should wait for large-scale clinical trials before jumping on the vitamin bandwagon and taking high doses.”

We should also “supplement” our diets with vitamins and minerals the old-fashioned way: by eating a wide variety of nutrient-rich foods, especially fruits and vegetables. Often.