Are vitamin pills good for you or not? Forty years ago, I was taught in medical school that they were useless, because you got all the vitamins you needed in a typical diet. What my teachers meant was that you got enough of the vitamins in your diet to prevent well-recognized vitamin-deficiency diseases. For example, you got more than enough vitamin C in your diet to prevent the disease called scurvy.
Over the next 30 years, however, lots of evidence emerged that people who ate diets rich in certain vitamins—particularly vitamins C, and E, and the B vitamins—had better health. In other words, the evidence suggested that vitamins had positive health effects beyond just preventing the rare vitamin-deficiency diseases. This led to the widespread use of daily multivitamin pills. But even more recently, a number of studies of vitamins B, C, and E in pill form failed to find health benefits, dousing the hopes of vitamin supplement enthusiasts.
A newly exciting vitamin
Until about 10 years ago, experts weren’t very interested in another vitamin—vitamin D. They thought the role of vitamin D was well understood—it helped keep bones strong—and that most people got all the vitamin D they needed through both diet and sun exposure. Vitamin D is unlike all of the other vitamins in that we get most of the vitamin D in our bodies from the sun: When sunlight hits our skin, the skin makes vitamin D.
Over the past decade, a series of surprising scientific studies has changed experts’ minds about the importance of vitamin D. First of all, many of the body’s tissues—not just bones—have receptors for vitamin D, suggesting that vitamin D may do more than just keep the bones happy.
Second, preliminary studies suggest that people with higher blood levels of vitamin D may have a reduced risk of getting autoimmune diseases like multiple sclerosis and diabetes, cancers (particularly colon cancer), and muscle weakness (that often leads to falls and broken bones in older people). One large study published in 2007 even found a lower risk of death in people who took regular vitamin D pills. Finally, studies have found that many adults—particularly those of us living in the northern part of the northern hemisphere, or the southern part of the southern hemisphere, where there is less sunlight in winter months—have low blood levels of vitamin D. People who are home-bound or living in institutions are at extra risk, as are dark-skinned people.
What does this mean to you?
So, the evidence is building that many of us are deficient in vitamin D, and that this could be putting our health at risk. Should we do anything about it and, if so, what? Since there has not been a large randomized trial of vitamin D pills, we have only indirect evidence to rely upon. For that reason, doctors are not unanimous in their judgment. Here’s what I think is the best assessment of the current evidence.
I think it is a good idea for the average adult to take a vitamin D supplement each day. The current recommendations are for a total of 400-800 IU (International Units) a day. (And this recommendation will probably go up to around 1,000 IU/day relatively soon). If you take a multivitamin pill, check to see how much vitamin D it contains, to see whether or not you need to take a separate vitamin D pill.
Most experts advise against taking more than 2,000 IU/day, because of possible toxic effects. I agree with this.
I don’t agree with some experts who recommend getting 15 minutes of sunlight each day, without using sun block. I think the benefits of this practice are outweighed by the risks of skin cancer.
Do you take extra vitamin D? Why do you take it? Do you try to get your vitamin D in other ways, besides through pills?
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