Riboflavin (or vitamin B2)

Vitamin B2, also called riboflavin, is one of the vital B vitamins that we need for full health. It is water soluble and yellow in colour, and as such is used as a food colour. It helps us activate other vitamins and minerals such as vitamins B6 and folate as well as iron.

Like other B vitamins riboflavin is used to produce energy. It is part of two chemicals, called FAD and FMN which help our cells produce energy from glucose and oxygen.

Riboflavin deficiency

Riboflavin deficiency is normally associated with deficiency in other B vitamins. It can affect alcoholics, anorexics and the lactose intolerant. Athletes and people with physically active occupations may require more than the rest of the population. There are also some drugs that affect how well riboflavin can be used by the body. Drugs for depression such as tricyclic anti-depressants and anti-psychotics such as chlorpromazine can affect how well riboflavin can be used by our bodies. Anti-convulsants, such as phenobarbitol and phenytoin can speed the breakdown of riboflavin, which could lead to deficiency.

In cases where riboflavin deficiency is present on its own the main symptoms centre around the mouth, tongue and throat, which become red, sore and swollen. The lips become cracked and blood vessels become visible over the eye. If deficiency continues then symptoms of vitamin B3 (pellagra) and B6 deficiency may also occur.

Riboflavin the food additive.

Vitamin B2 is classified as E101 in the European food supplementation scheme. It is used to colour foods yellow. You will often find it in sauces, processed cheese, pickled cucumbers, various enrichewd milk products as well as in breakfast cereals. If you ever see E101 on  the label of a packaged food you can rest assured that this particular colour will do you no harm. Many other colours used in food processing are not so benign.

Should I supplement riboflavin.

It is unlikely that you would supplement riboflavin on its own as it plays an important role in activating other B vitamins and iron. As such it is best taken as part of a B-complex supplement or multivitamin pill, where it can contribute synergistically to your wellbeing along with other important B vitamins and iron. 

People who are most likely to need vitamin B2 include heavy drinkers and those on the contraceptive pill. Both these drugs deplete the body of vitamin B2. Athletes, heavy labourers, and people over 50, are at increased risk of depletion either because they use up more, or because they don't consume enough B2.

Levels of riboflavin in supplements can be several time the recommended daily amount - RDA. There are currently no reports of serious toxicity with high levels of riboflavin supplementation, although there are some reports of increased sensitivity of the eyes to the sun. It may be advisable to wear sunglasses if you are supplementing more than 10mg per day. There is an upper limit on how much you can absorb from one dose of riboflavin of 27mg, so supplements containing more than this may be a waste of time(1).

Prevention of disease

There is some epidemiological evidence that vitamin B2 can help prevent certain conditions.


Cataracts are often caused by damage to proteins in the lens of the eye. The evidence is so far in the form of an association between higher intakes of vitamin B2 and reduced incidence of cataracts. However, as with many epidemiological studies, it could be that those with higher B2 intakes are consuming other nutrients that may be responsible for the reduced risk.


There is some reasonably convincing evidence that riboflavin supplementation can reduce the likelihood of migraine attacks(2). Some studies have used large amounts of 400mg/day(2), and others more modest amounts of 25mg/day(3). It is thought that the beneficial effects are due to the ability of riboflavin to support the energy plants called mitochondria in our brain cells.

Testing for riboflavin levels

A functional riboflavin test is available in the UK where the amount of an enzyme, glutathione reductase, that depends on vitamin B2 for its activation is measured. This is known as an EGR test whjere an erythrocyte glutathione reductase activation less than 1.20 is “normal”. This costs arounf £20 (or around £50 for B1, B2 and B6).

Where can I find B2 naturally?

Vitamin B2 can be found in foods such as liver, fish, meat, eggs and dairy produce. It also appears in plants such as green vegetables and asparagus. Processed foods are often fortified with vitamin B2, a common example being breakfast cereals.


1) http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=795872 p436 para1

2) http://www.ncbi.nlm.nih.gov/pubmed/9484373?dopt=Abstract

3) http://www.ncbi.nlm.nih.gov/pubmed/15447697?dopt=Citation