The ABCs of Vitamin B

What you need to know about the eight different types of this essential nutrient

carlosgaw / getty images

Constance Sommer,

AARP

En español

Published July 21, 2022

Thought much about B vitamins lately? If not, maybe you should.

There are eight varieties of B vitamins. And between them, they support brain health, heart health, DNA development and energy regulation. Plus, they’ve been found to prevent migraines, ward off recurrence of some skin cancers, and even possibly slow the progression of a devastating neurodegenerative disease.

Some people believe “the B stands for ‘boring,’ ” says Mark Moyad, M.D., director of preventive and alternative medicine education at the University of Michigan Medical Center in the department of urology.

The reality, he says, is when you look a little closer, the B vitamins “are one of the most fascinating categories in medicine.”

But like other vitamins, they should not be taken on a whim. There’s evidence, for example, that too much folic acid (vitamin B9) in supplement form can encourage the growth of cancer cells in older people, and an excess of biotin (vitamin B7) can mess with blood lab results.

“There’s some risks to taking supplements,” says Debbie Fetter, an assistant professor of nutrition at UC Davis. “They’re not entirely benign,” given that they can have side effects and even interfere with other drugs.

Experts recommend checking with your physician before you start any supplement, both to make sure it isn’t interacting with something you’re already taking, and to ensure that you’re not consuming excessive amounts of a nutrient you’re getting plenty of in your diet.

This particularly applies to B vitamins. Here’s what you need to know about them:

B1 (thiamine)

What it does: Thiamine helps to turn the food you eat into the energy your body needs, the National Institute of Health’s Office of Dietary Supplements explains. It’s especially essential for cell formation and function, and for brain and heart health, adds Sue-Ellen Anderson-Haynes, a Massachusetts-based nutritionist and spokesperson for the Academy of Nutrition and Dietetics.

Foods you can find it in: You’ll find thiamine in yeast, pork, brown rice, beans and lentils, and fortified breakfast cereals. That said, heating these foods can reduce the thiamine content, according to the Mayo Clinic.

How much you should be getting: The National Institute on Aging says men 51 and older need 1.2 milligrams (mg) per day; women 51 and older need 1.1 mg daily.

Who might need a supplement: Most people in the U.S. consume the recommended amounts of thiamine, according to the NIH. However, it’s worth noting that up to 20 to 30 percent of older adults may have some degree of thiamine deficiency, so talk to your doctor if you’re concerned. Health care providers may recommend individuals who consume too much alcohol, people with HIV, diabetics and people who had bariatric surgery supplement with thiamine, Anderson-Haynes says.

B2 (riboflavin)

What it does: It helps break down carbohydrates, proteins and fats, says the Mayo Clinic. And like vitamin B1, it plays a major role in cell growth and function.

Surprising benefits: A high dose can reduce migraine frequency by up to 50 percent, studies show, though researchers aren’t sure why.

Foods you can find it in: You’ll find riboflavin in eggs, organ meats, lean meats, low-fat milk, mushrooms, spinach, fortified cereals, breads and grain products, according to the NIH.

How much you should be getting daily: Men 51 and older should aim for 1.3 mg, and women 51 and older should get 1.1 mg, the NIA says. If you’re a migraine sufferer, your doctor may recommend a much higher dose (about 400 mg daily) as a preventive measure.

Who might need a supplement: Vegans, athletes who are vegetarians, and people who don’t consume dairy may have trouble meeting the recommended daily amount, the NIH says, and may benefit from a supplement. The same goes for people with a genetic disorder called riboflavin transporter deficiency.

B3 (niacin)

What it does: This one is also important in cell development, again helping to turn the food you eat into the energy you need, Anderson-Haynes says.

Surprising benefits: When taken in the form of nicotinamide (one of two main forms of niacin in dietary supplements; the other is nicotinic acid), it can reduce the risk of recurrent nonmelanoma cancers, a study in The New England Journal of Medicine suggests.

Foods you can find it in: Red meat, poultry, fish, nuts, legumes, seeds, brown rice, fortified cereals and grains, and bananas.

How much you should be getting daily: Men 51 and older should get 16 mg a day and women 51 and older need 14 mg, the NIA says.

Who might need a supplement: Those who have limited diets due to poverty or illness, those who consume too much alcohol, and individuals who may have carcinoid syndrome might benefit, according to the Harvard T.H. Chan School of Public Health. Most people get what they need in their diet.

B5 (pantothenic acid)

What it does: This B vitamin helps to break down fats and give the body energy.

Potential benefits: Researchers are looking into whether a B5 derivative, pantethine, may help lower cholesterol, slow the progression of Alzheimer’s, or even prevent or treat COVID and long COVID.

Foods you can find it in: Animal meat, seafood, eggs and milk, mushrooms (especially shiitakes), avocados, potatoes, broccoli, whole grains (brown rice, wheat, oats), peanuts, sunflower seeds and chickpeas

How much you should be getting daily: 5 mg for adults, the NIH says.

Who might need a supplement: Deficiency is rare; most Americans get enough B5 in their diet, the NIH says.

B6 (pyridoxine)

What it does: Vitamin B6 is a key player in more than 100 enzyme reactions involved in metabolism. It’s also important to immune function, the NIH says.

Surprising benefit: Increasing vitamin B6 intake may lower depression and anxiety in women, a large study published in the International Journal for Vitamin and Nutrition Research found.

Foods you can find it in: Tuna, salmon, beef liver, and potatoes and other starchy vegetables. You can also find B6 in fortified cereals, chicken, turkey, chickpeas, cottage cheese, squash, rice, bananas and spinach.

How much you should be getting daily: 1.7 mg for men and 1.5 mg for women, the NIH says.

Who might need a supplement: Those whose kidneys don’t work properly, who have autoimmune diseases, and those who consume too much alcohol, according to the NIH.

B7 (biotin)

What it does: It helps turn the carbohydrates, proteins and fats that we eat into energy the body needs.

Popular theory: Plenty of people say that taking biotin makes your hair, skin and nails stronger, but there isn’t a lot of evidence for that, experts say. Plus, the Food and Drug Administration says, taking biotin in supplement form can “significantly interfere with certain lab tests and cause incorrect results that may go undetected” — especially tests that diagnose heart attacks.

“Biotin interference is a major deal,” the University of Michigan’s Moyad says. He recommends patients stop taking biotin a couple of days before doing any blood test.

Foods you can find it in: Meat, fish, eggs, organ meats, seeds, nuts, sweet potatoes, broccoli and spinach, according to the NIH.

How much you should be getting: 30 micrograms (mcg) per day, the NIH says.

Who may need a supplement: Individuals who are dependent on alcohol and people with a rare genetic disorder called biotinidase deficiency.

B9 (folate /folic acid)

What it does: Folate helps in the production of genetic material (DNA and RNA). And research suggests it supports brain health and aids in mental and emotional health.

Surprising benefits: Some studies have found a link between low folate levels and depression.

Watch out: Older adults who take folic acid supplements may be at increased risk of cancer, particularly prostate cancer, researchers are discovering.

Popping folic acid supplements “is not as benign as people thought,” says Natalia Krupenko, a nutritional scientist at the University of North Carolina, who studies the interaction between folate and cancer. “Try to get it from your food,” she adds. Most supplements tend to contain more than the recommended daily dose of folic acid, according to the NIH.

Foods you can find it in: Beef liver, asparagus, brussels sprouts, dark, leafy greens like spinach or mustard greens, oranges and orange juice, nuts, beans and peas. In addition, folic acid is added to all kinds of grain foods, from breakfast cereals to corn tortillas, enriched rice and pasta, and bread.

How much you should be getting daily: 400 mcg

Who might need a supplement: Non-Hispanic Black women, people with disorders that lower nutrient absorption (like celiac or inflammatory bowel disease), people with a specific mutation in the MTHFR gene, and those who consume too much alcohol, the NIH says.

B12 (cobalamin)

What it does: B12 “is basically your energy vitamin,” Anderson-Haynes says. It helps to prevent a blood condition that makes people tired and weak, according to the NIH, and helps to keep the body’s blood and nerve cells healthy.

Surprising benefits: Ultra-high doses of the vitamin may slow the progression of ALS, a degenerative neurological disease, researchers recently discovered.

Watch out: Some drugs can lead to B12 deficiency, particularly ones taken for acid reflux (H2 receptor blockers like cimetidine, famotidine and ranitidine, and proton pump inhibitors like omeprazole, esomeprazole and lansoprazole). The common diabetes medication metformin may also affect vitamin B12 absorption.

Foods you can find it in: Meat (especially beef liver), poultry, clams, fish, eggs, dairy products and some fortified products like nutritional yeast, breakfast cereals and other grains

How much you should be getting daily: 2.4 mcg

Who might need a supplement: Somewhere between 3 and 43 percent of older adults have a vitamin B12 deficiency, according to the NIH. Your doctor can do a blood test to find out if your B12 levels are running low. Other risk factors for B12 deficiency include those with gastric disorders or who’ve had stomach surgery, who might not absorb enough B12; individuals with a condition called pernicious anemia; and vegetarians, vegans and infants of vegan women. “There’s a lot of different factors that can mess with your B12,” Moyad says. Symptoms of a B12 deficiency can include feelings of weakness and fatigue, says the NIH.

Should I take a B complex?

Probably not, unless you’ve been instructed by your physician, who can test you for any vitamin B deficiencies, including those more common in older adults.

“If you eat a good diet, you don’t need a B complex,” says Lisa Young, a nutritionist and professor at New York University. “Most of these nutrients are found in lots of foods, so a deficiency is going to be somewhat unlikely.” And when it comes to vitamins in supplement form, more isn’t always better.