What You Can Learn From People Who Take Vitamins (It's Not What You Think)
For decades, in study after study, people who take vitamin supplements have been shown to be healthier than people who don't. And yet, for just as long, in every good randomized trial where some people were given a supplement and others a placebo, taking the supplement gave no benefit. New published reports mean we finally have enough data to draw some definite conclusions. (See also: Know What You're Getting With Herbal Supplements)
The studies that suggested there might be a benefit were associational studies. Take a large population and divide them into the people who take supplements and the people who don't. Then, look at rates of various diseases for each group. In study after study, people who take supplements are healthier.
Scientists know that sort of study has limitations, so the next step would always be a proper randomized trial. Take a group of people and give them all a pill to take — with half the pills being a supplement and half the pills being a placebo. In those studies, in study after study, the people given the supplements did no better than the people given the placebo.
Vitamins Don't Improve Health — Habits Do
There's a reason why the sort of people who take supplements are healthier — they're different from the people who don't. They tend to be people who care more about their health. They eat more vegetables and less cured meats. They're less likely to smoke or to use alcohol to excess. They exercise more. They're more affluent. They get medical care when they have a health problem, and they get regular checkups. (See also: 6 Most Important Health Appointments)
Taking supplements is a marker for those behaviors — behaviors that actually improve your health.
Actually taking supplements, however, turns out to be a big waste of money. Worse, in many cases they actually do harm. (See also: Healthy Habits That Can Hurt You)
- Three trials of multivitamins, and twenty-four studies of single or paired vitamins randomly assigned for 400,000 people showed no beneficial effects on mortality, heart disease, or cancer.
- A large, long-term study showed a daily multivitamin did nothing to prevent cognitive decline among men age 65 or older. Similarly, multivitamins, B vitamins, E and C, and omega-3 fatty acids did nothing to improve cognitive function in people with mild to moderate dementia.
- High-dose multivitamins given to people who'd had a heart attack did nothing to prevent a recurrence.
- Antioxidants don't prevent chronic diseases, nor do folic acid or B vitamins.
- Taking β-carotene makes people with lung cancer die sooner.
- Taking high doses of vitamin E seems to make everybody die sooner.
For details and links to references, see Enough Is Enough: Stop Wasting Money on Vitamin and Mineral Supplements in Annals of Internal Medicine. (Most of the references are behind paywalls, but the summary is free.)
There's one possible exception: Vitamin D. If you live somewhere with long, dark winters — and especially if you always wear sunscreen when you're out in the sun — then maybe vitamin D supplements will do you some good. It doesn't take much sunshine to make your own vitamin D, though, if you've got pale skin. A ten-minute mid-day walk would be great. Just walking across the parking lot and back a couple of times a day will do the trick, if your arms and face are exposed to the sun. If you've got dark skin, it will take longer. (See also: Surprising Benefits of a 10-Minute Walk)
Also, the study specifically didn't try to look at prenatal vitamins. There's good evidence that folic acid supplements taken early in pregnancy prevent spina bifida. Go with whatever your doctor says, when it comes to prenatal care.
Eat better. Exercise more. Get regular checkups. Get your flu shot. Do all the things that the sort of person who takes supplements does. But you can quit spending money on supplements.
If you take multivitamins, will you continue to now that the science seems to be clear? Please share in comments!