Many people think that B vitamin supplements have health benefits and that any amounts, even high doses, are safe because they are water-soluble, meaning that what your body doesn’t need will simply pass into your urine. It’s important to get adequate amounts of all B vitamins. But, with a few exceptions, it’s unclear whether taking extra amounts as a supplement is beneficial. Dietary supplements can be costly, and some B vitamins can be toxic if you take too much. Vitamin B6, for example, can cause severe nerve damage if you take large amounts regularly. And high doses of niacin can cause flushing, headaches, rashes, and dizziness. Vitamin B12, on the other hand, seems safe at almost any dose.

A newly completed series of B vitamin fact sheets from the Office of Dietary Supplements (ODS) summarizes what you need to know about these important nutrients (see the full list below).

Our riboflavin fact sheet explains that while it’s not clear if this B vitamin helps prevent migraine headaches, some experts recommend trying it under the guidance of a healthcare provider.

Biotin is often found in dietary supplements promoted to improve the health of hair, nails, and skin, yet there’s little scientific evidence to support these claims.

“B vitamins are some of the most popular dietary supplements on the market, so it’s important that we understand their health effects,” said Joseph M. Betz, Ph.D., Acting Director of ODS. “ODS has cosponsored research studies on B vitamins to understand how they exert their effects in the body and whether they affect the risk of chronic disease.”

Our fact sheets explain that there are a few cases in which B vitamins do have proven health benefits. For example, folate, also called folic acid, helps reduce a woman’s risk of having a baby with a serious birth defect called a neural tube defect. The fact sheet explains why it’s important for a woman to get enough of this nutrient before becoming pregnant, as well as after learning she is pregnant.

“People can get adequate amounts of essential nutrients by eating a nutritious variety of foods, but in some cases, dietary supplements may be recommended,” said Anne L. Thurn, Ph.D., Director of the ODS Communications Program. “For example, people over 50 often have trouble absorbing the vitamin B12 found naturally in food, so they should get most of their vitamin B12 from dietary supplements or fortified foods.”

All of the B vitamin fact sheets are available as indepth health professional versions that are fully referenced, and as consumer versions in both English and Spanish.

“We hope that our fact sheets help consumers and healthcare providers navigate the sometimes confusing world of dietary supplements,” said Dr. Betz. “But it’s also important for people to talk with their healthcare provider for specific advice.”