New research on the benefits and harms of vitamins and supplements emerges
To optimize your health, your body needs a variety of vitamins and minerals. However, a question we're asked a lot is, "Is it worth it to take a vitamin?" If you believe the latest research, the answer is no.
Ultimately, there are two answers to this question, the first being that, for the most part, Americans are not deficient in vitamins. A recent CDC survey found that we're sufficiently nourished in essential nutrients like vitamins A, D and folate. But just because we aren't deficient, doesn't necessarily mean that our vitamin levels are optimal. The question is, how important are optimal levels?
"You get your nutrients through your food. Through the milenia, that’s what the case was and we survived as a species—in fact, we thrived," says Alice Lichtenstein, DSc, senior scientist and director of the Cardiovascular Nutrition Laboratory at the Jean Mayer U.S. Department of Agriculture (USDA) Human Nutrition Research Center on Aging at Tufts University and the author of a position paper on the usefulness of multivitamins. "To assume that we suddenly have lost this ability doesn't quite make sense."
While whole foods are a good source of nutrients, many public health researchers actually credit processed, packaged foods that have been fortified with vitamins for the nutrient-rich American diet. "Most people, if they are eating a generally healthy diet—not a perfect diet, but a generally healthy diet, don't need a multivitamin," says Katherine Zeratsky, a registered dietician at the Mayo Clinic. "With things like breakfast cereals, nutrition bars, foritified grains, and bread, which are all fortified with other minerals, we are getting more than we realize and more than we need."
This makes multi-vitamins more than redundant. In fact, it could make them dangerous. Lichtenstein points out that a large surplus of supplemental folate may have an adverse effect on colon cancer and other research has found a relationship between folic acid supplements and prostate and breast cancers as well. She adds that an overabundance of vitamin A, to levels of toxicity, can manifest in accelerated bone loss.
Some vitamins are water-soluble and others are fat-soluble, explains Zeratsky. While water-soluble vitamins will pass right through the body and are expelled in urine (the inspiration for the popular "expensive urine" quip among physicians), fat-soluble vitamins are stored and build up over time, making it a bit easier to reach toxicity. Fat-soluble vitamins include D, E and A— common inclusions in both fortified foods and in multivitamins.
What's more, a longitudinal study of women who took multi-vitamins and those who did not found that taking a regular multi-vitamin was actually associated with a shorter overall life expectancy. Critics of the study suggested that a bias may exist—namely, that people who take a multi-vitamin may be doing so in response to overall health problems that reduce their life spans.
Although, according to Lichtenstein, the average multi-vitamin user is a middle-aged woman who eats healthfully and exercises and has an above-average education level. “The population who takes them is most often the population who is least likely to need them,” she says.
But there are people who can benefit from a multi-vitamin or certain supplements. One example that all of the experts we spoke with gave was women of child-bearing age—and especially those trying to get pregnant—who should ensure that they get enough folate to prevent birth defects like spina-bifida. Additionally, women who are going through or have gone through menopause might need a boost in certain nutrients, and those on specialized diets that are lacking in nutrition might also benefit. Because it’s so highly individualized, a supplement regime should be planned with a doctor.
Still, there remains no evidence that multi-vitamins are useful to overall or long-term health—and there is some, albeit inconclusive evidence that they are harmful.
If you are going to take a multi-vitamin, Zeratsky says that she doesn't believe it will hurt. To ensure purity, she recommends looking for a brand that has been certified by a third party testing agency, like U.S. Pharmacopeal. Since vitamins and supplements are not regulated at the same level as food, it's important to know the source of what you're taking.
But long-term health isn't the primary concern at the center of this question. Some people report, in a clinical setting (as opposed to a significant study) that the family of B vitamins gives them extra energy, according to Zaretsky. Although B vitamins are prevalent enough in our diet to maintain basic levels, it's possible that people who have an energy response to B vitamins may be low in these nutrients without being deficient. The extra boost may also increase energy, as the vitamins play a role in regulating metabolism.
Beyond that, when it comes to exercise, important vitamins for energy, muscle function, recovery, and bone strength include vitamin D, vitamin C, and electrolytes such as potassium and sodium. Calcium is also really important, not only for bone health, but for regulating how our muscles contract, according to Zaretsky.
That said, it's better to get these nutrients from sunlight (in the case of the hormone, vitamin D) and whole foods. "Our healthy diet goes so far beyond what a pill can offer—known and unknown," says Zaretsky, pointing to the fiber and phytonutrients that foods contain and pills lack.
Agrees Lichtenstein: "The data generally supports better outcomes who are eating well-balanced diet. It's not particularly exciting, but from the perspective of what we can support in the research, that’s the best information we have."