Decades of research has failed to find any substantial evidence that the majority of vitamins and supplements do any significant good.
It seems like simple, obvious advice: Eat your vegetables, get some exercise, and — of course — take your vitamins.
Decades of research has failed to find any substantial evidence that vitamins and supplements do any significant good. In fact, recent studies skew in the opposite direction, finding that certain vitamins may be bad for you.
Several supplements have been linked with an increase in certain cancers, for example, while others have been associated with a rise in the risk of kidney stones. Still others have been linked with an overall higher risk of death from any cause.
So here are the vitamins and supplements you should take — and the ones you should avoid:
For decades, it was assumed that multivitamins were critical to overall health. Vitamin C to "boost your immune system;" vitamin A to protect your vision; vitamin B to keep you energized.
Not only do you already get these ingredients from the food you eat, but studies suggest that consuming them in excess can actually cause harm. A large 2011 study of close to 39,000 older women over 25 years found that women who took them in the long term actually had a higher overall risk of death than those who did not.
Vitamin D isn't present in most of the foods we eat, but it's a critical ingredient that keeps our bones strong by helping us absorb calcium. Getting sunlight helps our bodies produce it as well, but it can be tough to get enough in the winter. Several recent study reviews have found that people who took vitamin D supplements daily lived longer, on average, than those who didn't.
Vitamins A, C, and E are antioxidants found in plentiful form in many fruits — especially berries — and veggies, and they've been touted for their alleged ability to protect against cancer.
But studies suggest that when taken in excess, antioxidants can actually be harmful. A large, long-term study of male smokers found that those who regularly took Vitamin A were more likely to get lung cancer than those who didn't. And a 2007 review of trials of several different types of antioxidant supplements put it this way: "Treatment with beta carotene, vitamin A, and vitamin E may increase mortality."
A 2013 review of 29 trials which involved more than 11,300 people found "no consistent effect of vitamin C ... on the duration or severity of colds." The only place the authors observed some benefits of vitamin C supplementation was in marathon runners, skiers, and soldiers on "subarctic exercise" — and even in those small populations, the observed effect was small.
"The failure of vitamin C supplementation to reduce the incidence of colds in the general population indicates that routine vitamin C supplementation is not justified," the study authors wrote.
In addition to lacking in huge benefits, large doses of vitamin C may be harmful. Studies suggest that megadoses of 2,000 milligrams of the vitamin or more can raise your risk of painful kidney stones. To be safe, get your vitamin C from food. Strawberries are packed with the nutrient.
A large 2014 study of more than 25,000 people with heart disease found that putting people on long-acting doses of vitamin B3 to raise their levels of "good," or HDL, cholesterol didn't reduce the incidence of heart attacks, strokes, or deaths.
Plus, people in the study who took the B3 supplements were more likely than those taking a placebo to develop infections, liver problems, and internal bleeding.
Probiotics — pricey bacterial supplements that can cost upward of $1 per pill but are found naturally in smaller amounts in yogurt and other fermented foods — have become a big business with a market of roughly $23.1 billion in 2012.
The idea behind them is simple: Support the trillions of bacteria blossoming in our gut which we know play a crucial role in regulating our health.
But putting that idea into actual practice has been a bit more complicated. So far, the effects of probiotics have been all over the map. Sometimes they help, sometimes they don't. So rather than shelling out for a pill that promises to be a cure-all, snack on a parfait.
Unlike Vitamin C, which studies have found likely does nothing to prevent or treat the common cold, zinc may actually be worth it. The mineral seems to interfere with the replication of rhinoviruses, the bugs that cause the common cold.
In a 2011 review of studies of people who'd recently gotten sick, researchers looked at those who'd started taking zinc and compared them with those who just took a placebo. The ones on the zinc had shorter colds and less severe symptoms.
The antioxidant Vitamin E was popularized for its alleged ability to protect against cancer. But a large 2011 study of close to 36,000 men found that the risk of prostate cancer actually increased among the men taking Vitamin E compared to the men taking a placebo.
And a 2005 study linked high doses of Vitamin E with an overall higher risk of death. So if you're looking for more Vitamin E, make yourself a fresh spinach salad and skip the pill. Dark greens like spinach are rich with this stuff.
Folic acid is a B vitamin which our bodies use to make new cells. The National Institutes of Health recommends that women who are currently pregnant or who want to get pregnant take 400 micrograms of folic acid daily because their bodies demand more of this key nutrient when they are carrying a growing fetus.
Additionally, several large studies have linked folic acid supplementation before and during pregnancy with decreased rates of neural-tube defects, serious and life-threatening birth defects of the baby's brain, spine, or spinal cord.