Vitamin B2 (riboflavin)
Water-soluble B vitamin for energy release, growth and red blood cell production
Also known as
Definition
Vitamin B2 (riboflavin) is a water-soluble B vitamin that works closely with the other B vitamins. It is important for growth, supports the production of red blood cells and helps release energy from carbohydrates, proteins and fats. The body keeps only a small reserve; excess amounts leave it through the urine. A vitamin B test can measure the level in blood or urine.
| Parameter | Value |
|---|---|
| Unit | nmol/l or µg/l, depending on lab and method |
| Reference Range | No single range: labs use their own reference ranges depending on the sample (blood or urine) and method, and for some B vitamins it is not fully settled what a normal level is. The range on your own report is what counts; discuss deviations with your doctor. |
Agree on your personal target range with your doctor.
↓ What a low value means
A low value may be related to low intake or impaired use. Deficiency is rare in countries with a varied food supply. Risk factors for B vitamin deficiencies include alcohol use disorder, celiac disease, Crohn's disease, other absorption disorders, surgery on the digestive tract and a diet without animal foods. Severe riboflavin deficiency can come with anemia, sores on the mouth or lips, skin problems, sore throat and swollen mucous membranes. Your doctor handles the assessment.
↑ What a high value means
According to MedlinePlus, no poisoning from riboflavin is known, because excess amounts are excreted in the urine. For B vitamins in general: high levels can cause problems or may be related to an underlying condition such as liver disease. Discuss a raised value with your doctor.
When to test
A test is considered with symptoms that fit a deficiency or with risk factors such as absorption disorders in the gut, alcohol use disorder, surgery on the digestive tract or medicines that affect how B vitamins are used. Fasting for a few hours may be needed before a blood draw. Inflammation and some medicines can affect the result.
Frequently asked questions
Does the body store vitamin B2? +
Only to a small extent. As a water-soluble vitamin, riboflavin is not stored in large amounts; what the body does not need leaves through the urine. Regular intake from food is therefore needed to maintain the small reserve.
Which foods contain riboflavin? +
Among others, milk and dairy products, eggs, green leafy vegetables, lean meats, organ meats such as liver and kidneys, legumes and nuts. Breads and cereals are often fortified with it.
Why is riboflavin sensitive to light? +
Riboflavin is destroyed by light. Foods containing riboflavin should therefore not be stored in clear containers exposed to light.
How does the test work? +
Vitamin B2 can be measured in blood or urine, with urine as a single sample or a 24-hour collection. Before a blood draw, you may need to fast for a few hours; your practice or lab will give you the instructions.
Vitamin B2 (riboflavin)
Sources
Last updated: October 05, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.