Vitamin B2, also called riboflavin, is a water-soluble vitamin your body uses to convert food into energy. Adults need between 1.1 and 1.3 mg per day, and most people in Western countries get enough through dairy, meat, and fortified cereals. But B2 plays a surprisingly wide role in the body, from protecting your cells against oxidative damage to potentially reducing migraine frequency.
What Riboflavin Does in Your Body
Riboflavin’s main job is helping your cells produce energy. Once absorbed, your body converts it into two active forms that function as coenzymes, meaning they help other enzymes do their work. These coenzymes participate in dozens of metabolic reactions, including breaking down fats, proteins, and carbohydrates into usable fuel.
Beyond energy production, riboflavin supports your body’s antioxidant defenses. It helps regenerate glutathione, one of the most important molecules your cells use to neutralize harmful free radicals. This protective role extends to your eyes, skin, and red blood cells. Riboflavin also plays a part in activating other B vitamins, including B6 and folate, so a deficiency in B2 can create a ripple effect across multiple nutrient pathways.
How Much You Need
The recommended daily amount depends on your age and sex:
- Children 1 to 8 years: 0.5 to 0.6 mg
- Children 9 to 13 years: 0.9 mg
- Teen and adult men: 1.3 mg
- Teen and adult women: 1.0 to 1.1 mg
- Pregnant women: 1.4 mg
- Breastfeeding women: 1.6 mg
These amounts are easily achievable through a balanced diet. A single cup of milk plus a hard-boiled egg already gets you roughly halfway to an adult’s daily target.
Best Food Sources
Dairy products are the single biggest contributor to riboflavin intake in the U.S., U.K., and Ireland, followed by meat and fortified breakfast cereals. But the richest source by far is organ meat. Three ounces of pan-fried beef liver delivers 2.9 mg, more than double the daily requirement for any age group.
For more common foods, here’s what a typical serving provides:
- Plain fat-free yogurt (1 cup): 0.6 mg
- Milk, 2% fat (1 cup): 0.5 mg
- Grilled beef tenderloin (3 oz): 0.4 mg
- Clams (3 oz, cooked): 0.4 mg
- Swiss cheese (3 oz): 0.3 mg
- Hard-boiled egg (1 large): 0.26 mg
- Cooked spinach (½ cup): 0.21 mg
- Grilled portabella mushrooms (½ cup): 0.2 mg
Vegetables like broccoli, asparagus, and spinach contribute smaller amounts, but they add up across a full day of eating.
How Cooking Affects Riboflavin
Riboflavin holds up well to heat, which sets it apart from more fragile vitamins like vitamin C. Cooking chicken retains between 46% and 94% of its riboflavin depending on the method, and blanched or processed peas and lima beans keep more than 70%. The main way you lose riboflavin during cooking is through leaching: the vitamin dissolves into cooking water and gets poured down the drain. Steaming, roasting, or using less water helps preserve more of it.
Light is a different story. Riboflavin is highly sensitive to UV and visible light, which is one reason milk now comes in opaque containers rather than clear glass bottles. If you store riboflavin-rich foods in direct sunlight, degradation happens quickly. Keep milk, eggs, and grains in dark or opaque packaging when possible.
How Your Body Absorbs It
Riboflavin is absorbed primarily in the small intestine through specialized transport proteins. Your body has three distinct riboflavin transporters expressed in different tissues. Two of them are active in the small intestine, shuttling the vitamin from your gut into the bloodstream. A third is highly concentrated in the brain, which underscores how important riboflavin is for nervous system function.
Because riboflavin is water-soluble, your body doesn’t store large reserves of it. Excess amounts are excreted in urine, which is why taking a B-complex supplement often turns your urine bright yellow. This also means riboflavin has very low toxicity. No tolerable upper intake level has been established because even high supplemental doses haven’t produced harmful effects in studies.
Signs of Deficiency
Riboflavin deficiency, sometimes called ariboflavinosis, tends to show up first in tissues that turn over quickly: skin, the lining of your mouth, and your eyes. Early signs include cracks at the corners of your mouth, a sore or swollen throat, and a swollen, reddened tongue. Skin around the mouth and nose may become itchy, flaky, or develop a form of dermatitis.
As deficiency progresses, you may notice blurred vision, fatigue, and even depression. Hair loss, liver problems, and reproductive issues can occur in more severe cases. Deficiency rarely happens in isolation. Because riboflavin helps activate other B vitamins, being low in B2 often means your body can’t properly use B6 and folate either, compounding symptoms.
People most at risk include those with very limited diets, heavy alcohol use, or certain genetic conditions affecting riboflavin transport. Vegans who don’t consume fortified foods or supplements may also fall short, since the richest natural sources are animal-based.
Riboflavin and Migraine Prevention
One of the most studied uses of supplemental riboflavin is preventing migraines. The theory centers on energy metabolism: some migraine sufferers appear to have impaired energy production in their brain cells, and high-dose riboflavin may help correct this.
In adults, clinical trials using 400 mg per day (roughly 300 times the RDA) have shown consistent benefits. One trial found a 68% improvement in migraine severity scores. Another reported that headache frequency dropped from 4 days per month to 2 days per month after three months at the same dose, and roughly 63% of participants in a separate study were classified as responders. Multiple trials have found that 400 mg daily reduces both the frequency and number of headache days compared to placebo.
Results in children and adolescents are more mixed. Some pediatric trials using 200 to 400 mg daily found significant reductions in headache frequency and duration within three to four months. Others, particularly at lower doses like 50 mg, showed no meaningful difference from placebo for migraines specifically (though one did reduce tension-type headaches). The most consistent pediatric results come from doses of 400 mg daily for at least three months.
The 400 mg dose used in migraine trials is far above what you’d get from food alone, so this is strictly supplement territory. Given riboflavin’s strong safety profile and lack of a known toxic threshold, it’s considered a low-risk option, which is part of why it’s gained traction as a migraine preventive strategy.