Vitamin B2, also called riboflavin, is one of the eight B vitamins your body depends on to function properly. It helps turn the food you eat into energy and plays a key role in keeping your cells healthy, especially those that produce energy. It’s essential not just for metabolism, the process by which your body converts calories into fuel, but also for supporting your body’s defenses against harmful molecules called free radicals, which are linked to aging and chronic diseases.
When you eat foods containing vitamin B2—like milk, eggs, leafy greens, meat, and fortified cereals—your digestive system breaks it down and absorbs it in the small intestine. Once inside the body, vitamin B2 is converted into two active forms called FMN and FAD. These are helpers (known as “coenzymes”) that allow enzymes—your body’s biological machines—to do their jobs. These helpers are crucial for many chemical reactions that release energy, especially inside mitochondria, the parts of your cells known as the “power plants.”
Vitamin B2 is essential for energy production, especially in the heart, muscles, liver, and brain, organs that use a lot of energy. It helps drive the breakdown of carbohydrates, fats, and proteins, and supports a critical cycle called the electron transport chain. This is the final step your body uses to make ATP, your cells’ main energy source.
Vitamin B2 is also part of the system that recharges glutathione, one of your body’s most important antioxidants. Antioxidants are substances that help protect your cells from oxidative stress, a type of cellular “rust” that damages tissues over time and contributes to conditions like heart disease, Alzheimer’s, and cancer.
When your body doesn’t get enough vitamin B2, energy production slows and you may notice vague symptoms like tiredness or weakness. But deficiency can also cause more visible signs like cracked lips, red and swollen tongue, sore throat, skin rash (especially around the nose and mouth), or even light sensitivity. These symptoms happen because vitamin B2 is essential for healthy skin, mucous membranes (the moist linings inside your mouth and throat), and red blood cells.
Deficiency, called ariboflavinosis, can result from poor diet, digestive disorders (like celiac disease), long-term use of certain medications (such as barbiturates), or conditions that increase nutritional needs, such as pregnancy, heavy exercise, or anorexia. People who avoid dairy (a major source of vitamin B2) or eat a very limited diet are more likely to have low levels
Vitamin B2 does more than just prevent symptoms of deficiency. It supports healthy aging by helping reduce oxidative stress, and may protect against certain chronic diseases. For example, it plays a role in managing homocysteine, a substance that, at high levels, is linked to heart disease. By helping convert homocysteine into other useful compounds, vitamin B2 may help lower cardiovascular risk, especially in people with certain genetic variations that make them more sensitive to B-vitamin levels.
Vitamin B2 also helps your body use other nutrients. It’s needed to activate vitamin B6 and convert the amino acid tryptophan into niacin (vitamin B3). These roles make it a kind of “behind-the-scenes” vitamin that keeps your nutrient network running smoothly.
In higher-than-normal doses, vitamin B2 has been used to prevent migraines. Studies suggest that taking 400 mg daily, much more than the recommended amount for general nutrition, can reduce how often migraines occur and how severe they are. This is thought to be because vitamin B2 improves the way energy is made in brain cells.
It also has medical uses in treating rare genetic conditions that affect energy metabolism, like multiple acyl-CoA dehydrogenase deficiency (MADD) and Brown-Vialetto-Van Laere syndrome. In these disorders, problems with vitamin B2 transport or use can severely impair the body’s ability to generate energy. High-dose vitamin B2 can sometimes restore the function of defective enzymes and improve symptoms.