Guide to Vitamins

Should I Take B Vitamins?

The lowdown on thiamin, folate, B6, B12, and more

Markham Heid
Published in
5 min readNov 11, 2019


Illustrations by Kieran Blakey

This story is a part of The Elemental Guide to Vitamins. Here are the vitamins and supplements that are covered: multivitamins, vitamin D, vitamin C, calcium, B vitamins, omega-3, vitamin E, fiber, protein, and probiotics.

InIn the late 1800s, a Dutch physician named Christiaan Eijkman traveled to the East Indies to study a nerve disease called beriberi that causes pain, confusion, a racing heart, and, in extreme cases, death.

Scientists at the time believed beriberi was caused by some kind of infectious germ. But Eijkman recognized that local chickens that were fed only white rice, as opposed to those fed brown rice, developed a form of leg paralysis that seemed related to beriberi symptoms in humans. This observation contributed to the discovery of thiamin, also known as vitamin B1, which is found in brown rice and other foods and which humans (and apparently chickens) need for proper cell health and functioning.

Along with thiamin, most people are familiar with three other B vitamins: B9 (aka, folate), B6, and B12. But there are eight B vitamins in all, and every one of them plays an important role in the function of the body’s cells and enzymes. In fact, they’re grouped together as “B” vitamins because of their closely related roles in cell and enzyme health.

“B12 is really critical from head to toe.”

Vitamin B12, for example, supports cell health and also helps the body make new DNA. People who don’t get enough B12 may feel tired and weak and can experience a loss of appetite, weight loss, confusion, or nerve pain. Anywhere between 1.5% and 15% of Americans are deficient in B12. People older than 50 and those on vegan or vegetarian diets are at greatest risk, according to the National Institutes of Health. (Animal products are the only ones that naturally contain B12, although many breakfast cereals, “alternative” milks, and other food products are fortified with it.)

“B12 is really critical from head to toe,” says Dr. Mark Moyad, the Jenkins/Pokempner director of preventive and alternative medicine at the University of Michigan. “If you’re low on B12, that can cause nerve and memory problems or anemia, or it can even mimic the symptoms of a neurological disease like multiple sclerosis.”

Moyad says B12 is starting to get more attention from doctors. But it’s “dirt cheap” to produce, which means most supplement makers don’t have a financial incentive to study or promote it. “There are a lot of people charging a lot of money for B12 injections, but in head-to-head trials, a cheap pill works just as well,” he adds.

There’s evidence that people who are B12 deficient may improve their energy and endurance by taking a supplement. And there are some preliminary studies linking B12 pills to blood changes that may benefit those at risk for dementia. While none of those benefits is well-established, B12’s safety profile may be the best of the popular supplements. It can interfere with the action of some prescription drugs, including some antibiotics and the diabetes drug metformin. But otherwise, there aren’t any established risks associated with B12 pills.

B12 aside, folate supplements are usually recommended for women who are pregnant or trying to get pregnant. Research from Harvard Medical School and elsewhere has found that folate helps protect against neural tube defects in newborns, and it may offer other prenatal benefits. Beyond B12 and folate, however, the research backing other B vitamin supplements is all over the map.

A small 2018 study found that people who took a multivitamin packed with high doses of B vitamins experienced a drop in inflammation and oxidative stress, both of which are likely drivers of a variety of diseases — including heart disease and cancer. “People who have less healthy diets or extreme diets could benefit” from a B vitamin supplement, says Luke Downey, co-author of the study and an associate professor of health sciences at Swinburne University of Technology in Australia. On the other hand, “people who have a varied and healthy diet are unlikely to notice any real benefit from taking supplements.”

More research from Downey has found that people who took a B vitamin complex, which is a mixture of all the B vitamins, reported an improved mood, less confusion, and less stress. But he says other studies have not turned up these benefits. Some have even turned up risks. In certain patient groups — such as those with diabetes — a B vitamin complex may cause a worsening of nerve-related symptoms.

“I think the rest of the B’s” — meaning, everything but vitamin B12 and folate — “are overrated,” Moyad says. While they’re important, “the body’s requirements for most of them are low, and you get all of them in food.”

He says that taking a low-dose B12 supplement may be a good idea, especially for people who don’t eat animal products or foods fortified with B12. But it may be hard to find a product that’s truly low-dose. A 2019 analysis from, an independent company that tests consumer supplements for safety, found that most B12 supplements contain far more than the 2.4-microgram daily requirement. That site recommends breaking up the pill or taking liquid B12 doses, many of which top 50 micrograms.

The bottom line: The body needs its B vitamins. And it’s worthwhile to supplement B12 and folate if you need it. Though keep in mind that most people are likely getting what they need from their diet.

This story is a part of The Elemental Guide to Vitamins.



Markham Heid

I’m a frequent contributor at TIME, the New York Times, and other media orgs. I write mostly about health and science. I like long walks and the Grateful Dead.