Get to Know Vitamin B2

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Get to Know Vitamin B2

This is the third piece in a series on vitamins and minerals, also called micronutrients. In this series, we’ll cover what each micronutrient does, food sources, supplements, and signs of deficiencies and excess.

Vitamin B2 is part of the B-complex vitamin family. Also known as riboflavin, this vitamin plays a role in energy production for the body, but it has other jobs, too. Read on to learn more!

What is vitamin B2?

Vitamin B2 (aka “riboflavin”) is a water-soluble B vitamin. It’s found naturally in many foods, and it’s also available as a dietary supplement. In addition, bacteria in the gut make small amounts of vitamin B2, although not in amounts sufficient to meet daily requirements.

What does vitamin B2 do?

Vitamin B2, along with the other B vitamins, helps the body produce energy from the foods that we eat. This vitamin is part of two major coenzymes (substances that help to enhance the action of an enzyme), flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). These two coenzymes play a major role in energy production, cellular function, growth, and development, and in the metabolism of fats, drugs, and steroids, according to the Office of Dietary Supplements (ODS), which is part of the National Institutes of Health.

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There are other roles that vitamin B2 plays, as well. These include:

  • Helping the body change vitamins B6 and folate into useable forms
  • Promoting the growth and development of red blood cells
  • Promoting healthy vision
  • Working as an antioxidant to fight off free radicals which can damage cells

Some research indicates that vitamin B2 may help prevent migraines. The studies using vitamin B2 have been small, but in one study with 55 adults who had migraines, taking 400 milligrams of this vitamin daily reduced the frequency of migraines by two per month compared with placebo (an inactive substance). While more research is needed, the ODS says that the Quality Standards Subcommittee of the American Academy of Neurology and the American Headache Society “concluded that riboflavin is probably effective for preventing migraine headaches and recommended offering it for this purpose.”

Health experts have been looking at the possible role that vitamin B2 may play in cancer prevention, specifically for lung and colorectal cancers. Results have been inconclusive, however.

Studies show that taking riboflavin may reduce homocysteine levels in the blood. Homocysteine is an amino acid and high levels are linked with certain medical conditions, including heart attack, stroke, and dementia. Research doesn’t indicate that taking vitamin B2 or any B vitamin supplements lowers the risk of heart attacks or deaths from heart disease, and the American Heart Association does not recommend the use of B vitamin supplements for reducing heart disease risk.

What foods have vitamin B2?

Vitamin B2 is found in a number of different foods, primarily in meat and fortified foods. Top sources are:

  • Beef liver
  • Lean beef and pork
  • Chicken
  • Eggs
  • Clams
  • Fortified breads and cereals
  • Milk
  • Yogurt
  • Almonds
  • Green leafy vegetables
  • Legumes
  • Nuts

Vitamin B2 is also found in multivitamin/mineral supplements, B-complex vitamin supplements, and supplements containing just vitamin B2 (riboflavin).

How much vitamin B2 do you need?

The Recommended Daily Allowance for vitamin B2 is as follows:

  • For men age 19 and older: 1.3 milligrams (mg) daily
  • For women age 19 and older: 1.1 mg daily
  • For pregnancy: 1.4 mg daily
  • For lactation: 1.6 mg daily

What are signs of vitamin B2 deficiency?

Vitamin B2 deficiency is rare in the United States. The 2003-2006 National Health and Nutrition Examination Survey (NHANES) showed that less than 6% of the U.S. population had vitamin B2 intakes below daily recommendations.

Signs of vitamin B2 deficiency (also called “ariboflavinosis) include:

  • Skin disorders
  • Cracked lips
  • Cracks in the corners of the mouth
  • Swelling of the mouth, tongue and throat
  • Sore throat
  • Hair loss
  • Anemia
  • Red and itchy eyes
  • Cataracts

Vitamin B2 deficiency typically occurs along with deficiencies in the other B vitamins.

Some groups of people are more likely than others to not get enough vitamin B2:

  • Athletes who are vegetarians
  • People who abuse alcohol
  • People who have anorexia
  • People with lactose intolerance
  • Pregnant women who consume little dairy foods or meat
  • Vegans and vegetarians

What are signs of vitamin B2 toxicity?

There is no known toxicity observed with vitamin B2, since this vitamin is water soluble and the amount that is absorbed in the digestive tract is limited. Adverse effects from high vitamin B2 intakes from foods or supplements have not been reported. But data is limited and this does not mean that high intake of vitamin B2 do not cause adverse effects.

High doses of vitamin B2 supplements may cause your urine to turn bright yellow (which is harmless), and might cause diarrhea and an increase in urination (let your health care provider know if you have either of these side effects).

Other things to know about vitamin B2

Ultraviolet and visible light can inactivate vitamin B2, which is why you will rarely see milk stored in clear glass bottles.

Because vitamin B2 is water soluble, about twice as much of this vitamin is lost in cooking water when foods are boiled. Less is lost when foods are steamed or microwaved.

Learn more about vitamins and minerals by reading the other pieces in this series:

Get to Know Vitamin A

Get to Know Vitamin B1

Get to Know Vitamin B3

Get to Know Vitamin B5

Get to Know Vitamin B6

Get to Know Vitamin B7

Get to Know Vitamin B9

Amy Campbell, MS, RD, LDN, CDCES

Amy Campbell, MS, RD, LDN, CDCES

Amy Campbell, MS, RD, LDN, CDCES on social media

A Registered Dietitian and Certified Diabetes Educator at Good Measures, LLC, where she is a CDE manager for a virtual diabetes program. Campbell is the author of Staying Healthy with Diabetes: Nutrition & Meal Planning, a co-author of 16 Myths of a Diabetic Diet, and has written for  publications including Diabetes Self-Management, Diabetes Spectrum, Clinical Diabetes, the Diabetes Research & Wellness Foundation’s newsletter,, and

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