More than half of American adults take dietary supplements. Now a major new study finds that supplements either do no good or increase the risk of dying from cancer or heart disease.
On the front of its Personal Journal section, the Wall Street Journal points out that investigators followed some 39,000 women for approximately 19 years. The New York Times reports in “Vital Signs” that “some supplements, like iron, were associated with a substantial increase in the risk of death, while others – vitamin A and vitamin D, for example – had no effect.”
“As in the broader population, women in the study who took supplements tended to be healthier – with lower rates of diabetes and high blood pressure, and lower body mass index – than women who didn’t,” the Los Angeles Times reports. Still, “with the exception of the women taking calcium, they died at slightly higher rates.”
The Times points out, however, that researchers “did not explore whether supplements contributed to the causes of death among the women.”
Still, USA Today reports, “The study highlights concerns about the long-term use of supplements and vitamins in people who do not have severe nutritional deficiencies,” the investigators said.
An accompanying editorial notes that [the] findings “add to the growing evidence demonstrating that certain supplements can be harmful.
In the past, I’ve warned you about the potential risks of multivitamins. (see my blog: Are multivitamins helpful or harmful when it comes to preventing chronic diseases?)
Overall, we now have a spate of high-profile studies published in the last few years showing that a variety of popular supplements — including calcium, selenium, and vitamins A, C and E — don’t do anything to reduce the risk of developing heart disease, stroke, or a variety of cancers. And, in the past few years, several high-quality studies have failed to show that extra vitamins, at least in pill form, help prevent chronic disease or prolong life.
Some physicians continue to recommend them as a backstop for patients whose diets may contain nutritional gaps. And since they don’t require a prescription, many people simply assume they are safe.
But those assumptions may not be warranted, especially if people wind up overdosing on vitamins and minerals.
Nevertheless, there are vitamins that may be helpful. Calcium can strengthen bones, reduce the risk of fractures, and reduce the risk of colon polyps or perhaps colon cancer. And, as readers to this website know, there have been dozens of studies published this last year on the benefits of vitamin D (leading the American Academy of Pediatrics to double the recommended daily dose for children and teens).
Vitamin D looks really promising, bbut 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.
In the meantime, I think I’m going to apply these studies in two ways:

•  I’m going to quit taking a daily multivitamin and just concentrate on eating a more nutritious diet.
• I’m not only not going to recommend multivitamins for the vast majority of my patients (pregnant patients excluded), but actively discourage them from taking multivitamins.