Vitamin B2 (Riboflavin)

What is riboflavin?

Riboflavin, or vitamin B2, is a water-soluble B vitamin. It forms two coenzymes, FAD and FMN, that the body needs to produce energy, process fats and medicines, and use other B vitamins, including vitamin B6. Adult men need 1.3 mg a day and adult women 1.1 mg a day (NIH ODS).

What the research says

Riboflavin is best known in research for migraine prevention, where high doses have been studied. Its link to sleep is much weaker. Some sleep products include it because it helps activate vitamin B6, which is involved in making serotonin and melatonin, and some observational studies have looked at dietary B2 intake and sleep. Observational links cannot show cause and effect, and we found no well-designed trials showing that riboflavin supplements improve sleep in people who already get enough.

Most people in the United States meet their needs from food. Eggs, organ meats, lean meats, milk and fortified grains are rich sources, and milk and bread are among the largest contributors to intake in the US diet (NIH ODS). Deficiency is uncommon and usually occurs alongside other nutrient shortfalls.

Some groups are more likely to run low, according to ODS, including vegetarian athletes, vegans and people who consume little milk, and pregnant or breastfeeding women who rarely eat meat or dairy, along with their infants. People with a rare inherited condition called riboflavin transporter deficiency also need medical treatment with high doses. In these situations, the right step is to talk with a clinician about diet and testing.

For sleep specifically, riboflavin’s inclusion in a formula is best read as general nutritional support rather than an active sleep ingredient. ODS notes that riboflavin’s solubility and absorption in the gut are limited, which may be why high intakes from food show no observable toxicity. If a product leans on riboflavin to justify sleep claims, treat that as a sign that the marketing is stretching the evidence.

How it’s used in supplements

Riboflavin appears in multivitamins, B-complex products and many energy, sleep and migraine formulas. It can turn urine bright yellow, which is harmless.

Riboflavin appears to have very low toxicity. Because no adverse effects were reported from high intakes, even 400 mg a day for at least three months, the Food and Nutrition Board did not set an upper limit. ODS still urges caution about consuming excessive amounts, and notes that riboflavin is not known to have clinically relevant interactions with medications (NIH ODS). As with any supplement, tell your doctor what you take, especially if you are pregnant or managing a chronic condition.