Vitamin B2 (Riboflavin)
What it does and why you need it
Riboflavin (vitamin B2) is part of two coenzymes (FAD and FMN) that the body uses to drive energy metabolism and to recycle other B vitamins. It also has a role in skin and mucous membrane health, and in vision (riboflavin deficiency is one cause of eye irritation and light sensitivity).
Riboflavin is destroyed by sunlight, which is why milk in opaque cartons or coloured plastic protects the content better than clear-glass bottles. Cooking losses are modest.
Best food sources
Values per 100g from USDA SR Legacy and McCance and Widdowson 7th edition; the site's food entries currently store macros only.
| Food | Typical UK portion | Riboflavin per portion | % men's RNI |
|---|---|---|---|
| Milk | 200ml (a small glass) | around 0.4mg | 31% |
| Plain yoghurt | 125g (one pot) | around 0.35mg | 27% |
| Egg, whole | One medium, around 50g | around 0.25mg | 19% |
| Mushrooms, cooked | 80g | around 0.3mg | 23% |
| Fortified breakfast cereal (UK label) | 30g | around 0.4mg, check the pack | around 30% |
| Cheddar cheese | 30g | around 0.15mg | 12% |
A glass of milk plus a yoghurt plus eggs at breakfast covers the day for most adults; for vegans, fortified plant milk and fortified cereal play the same role.
UK reference intake by age and sex
UK Reference Nutrient Intake (RNI) for riboflavin is set by SACN (1991).
| Group | Daily riboflavin (mg) |
|---|---|
| Babies, 0 to 12 months | 0.4 |
| Children, 1 to 3 years | 0.6 |
| Children, 4 to 6 years | 0.8 |
| Children, 7 to 10 years | 1.0 |
| Boys, 11 to 14 years | 1.2 |
| Girls, 11 to 14 years | 1.1 |
| Men, 15 years and over | 1.3 |
| Women, 15 years and over | 1.1 |
| Pregnancy | 1.4 (an increment of 0.3) |
| Breastfeeding | 1.6 (an increment of 0.5) |
Deficiency signs and who is at risk
Riboflavin deficiency is rare in the UK general population because dairy is so widely eaten. When it occurs, signs include cracks at the corners of the mouth (angular stomatitis), a sore, red tongue, eye irritation and light sensitivity, and skin rashes around the nose. It can co-exist with deficiencies of other B vitamins.
At higher risk in the UK
- Vegans whose diet does not include fortified products.
- People with severely restricted diets, eating disorders, or food insecurity.
- People with malabsorption conditions.
- Heavy alcohol use.
Too much: safe upper limit
Riboflavin from food is not a realistic concern; the body excretes the excess (a noticeably yellow urine after a B-complex supplement is the riboflavin going out, and it is harmless).
NHS supplement guidance: taking 40mg or less a day of riboflavin in supplements is unlikely to cause any harm.
Supplements and UK guidance
Routine riboflavin supplementation is not needed for adults eating dairy or fortified plant alternatives. Higher therapeutic doses are used in some specific situations (notably migraine prevention) on specialist advice; this is not general advice.
For vegans: a daily B-complex or multivitamin that includes riboflavin is a reasonable backstop if fortified products are not part of the regular shopping pattern.
Related
- Also used as a food colour: E101 riboflavin.
- The B-vitamin family: Vitamin B1, Vitamin B3, Vitamin B6, Folate, Vitamin B12.
- Best food sources: Milk, Plain yoghurt, Eggs, Mushrooms.
Sources and references
- NHS. Vitamins and minerals: Vitamins B. nhs.uk/conditions/vitamins-and-minerals/vitamin-b.
- SACN. Dietary Reference Values for Food Energy and Nutrients for the United Kingdom. Department of Health Report 41 (1991).
- Public Health England. McCance and Widdowson's The Composition of Foods, 7th summary edition (2015).
This page is reference information for UK shoppers. It is not medical advice.