How much money would the US auto industry be making if every car they sold never started? How much could video game console makers charge if their products didn’t play any games? Well, in 2010 the US dietary supplement industry sold $28 billion dollars in vitamins, minerals and other supplements that, as far as we can tell, benefited virtually no one.

The current issue of Annals of Internal Medicine published three studies examining the effects of multivitamins. This is not the first investigation of a mysterious unexplored field. Lots of studies have already shown that in well-nourished people living in the Western Hemisphere, multivitamins are not helpful. Think of this more as sweeping away any traces of doubt.

One study explored the effects of a high-dose vitamin and mineral supplement on heart disease. About 1,700 patients who had a heart attack in the past were randomized to the supplement or a placebo. They were followed for four years to measure their rates of recurrent cardiovascular events. There was no difference in the occurrence of these events between the group receiving the supplement and the group receiving placebo.

Another study examined the effects of a multivitamin on cognitive decline. About 6,000 male physicians aged 65 and older were randomized to a multivitamin or placebo and given a battery of five tests of cognition and memory over 12 years of follow up. The two groups did the same.

The third study was a review of prior studies of vitamin and mineral supplements for the prevention of cancer or cardiovascular disease. The study conclusion was negative. There is no reason to take vitamins or minerals for cancer or cardiovascular disease prevention. And the review highlighted the harms of some vitamins. β-carotene and vitamin A increase lung cancer risk in smokers, and vitamin E increases the risk of prostate cancer.

An editorial in the same journal issue crystalized our current knowledge.

In conclusion, β-carotene, vitamin E, and possibly high doses of vitamin A supplements are harmful. Other antioxidants, folic acid and B vitamins, and multivitamin and mineral supplements are ineffective for preventing mortality or morbidity due to major chronic diseases.

Their conclusion:

The message is simple: Most supplements do not prevent chronic disease or death, their use is not justified, and they should be avoided.

There are specific patient populations who are especially vulnerable to vitamin malabsorption, such as those who have had intestinal surgery and patients on long-term acid suppressing medications. They may be recommended specific vitamin supplements. Women in their child-bearing years should take folic acid. And it’s possible that vitamin D in the elderly prevents falls. But apart from those narrow groups, well-nourished people don’t benefit from supplements. (I don’t take any vitamins or minerals.)

Perhaps the latest studies and the barrage of resulting media coverage will make a difference. Then maybe we could save some of that $28 billion and spend it to buy some skepticism.

Learn more:

Multivitamins Found to Have Little Benefit (Wall Street Journal)
How do Americans waste $28 billion a year? On vitamins, doctors say (Los Angeles Times)
The Case Against Multivitamins Grows Stronger (Shots, NPR’s health news)
Oral High-Dose Multivitamins and Minerals After Myocardial Infarction: A Randomized Trial (Annals of Internal Medicine article. Abstract available without subscription)
Long-Term Multivitamin Supplementation and Cognitive Function in Men: A Randomized Trial (Annals of Internal Medicine article. Abstract available without subscription)
Vitamin and Mineral Supplements in the Primary Prevention of Cardiovascular Disease and Cancer: An Updated Systematic Evidence Review for the U.S. Preventive Services Task Force (Annals of Internal Medicine. Available without subscription.)
Enough Is Enough: Stop Wasting Money on Vitamin and Mineral Supplements (Annals of Internal Medicine editorial. Subscription required.)
A Reminder to Dump Your Multivitamin (my post from 2011 reviewing the known effects of various vitamin supplements)