Find out more about the recommended daily intake, symptoms of deficiency and whether you should consider a supplement.
Medically reviewed by Dr Juliet McGrattan (MBChB) and words by Piriya Mahendra Pordes
The bacteria that live naturally in our bowel produce biotin so it remains unclear whether we need additional biotin from our diet.
Vitamin B7 is often recommended for strengthening hair and nails and it’s found in many cosmetic products for hair and skin. There is, however, little evidence to prove any benefit.
Vitamin B7 daily needs
There is no recommended daily allowance (RDA) of vitamin B7 in the UK because there isn’t enough evidence to set one. A suggested amount that is safe and adequate is 20µg (micrograms) per day.
Vitamin B7 deficiency
What happens if I don’t have enough vitamin B7? Vitamin B7 deficiency is extremely rare. This is because vitamin B is produced by bacteria in the intestine and is widely available in food.
Vitamin B7 deficiency can be caused be eating raw egg whites (two or more a day) over many months, as raw egg white contains a protein called avidin, which binds to vitamin B7.
People with genetic disorders, such as biotinidase deficiency, multiple carboxylase deficiency and holocarboxylase synthetase deficiency are also susceptible to vitamin B7 deficiency.
Vitamin B7 deficiency symptoms
Symptoms of deficiency include:
- a fine scaly seborrhoeic dermatitis and/or a red rash, usually on the face
- brittle hair or hair loss
- poor co-ordination of body movements (ataxia)
- loss of appetite and nausea
- mild depression
- birth defects (reported in animals)
- possible reduced immunity and susceptibility to bacterial/fungal infections
Vitamin B7 best foods sources
Good food sources of vitamin B7 include:
- egg yolk
- seeds and nuts e.g almonds
- green, leafy vegetables such as spinach and Swiss chard
- sweet potatoes
- saskatoon berries
What are the effects of cooking on vitamin B7? Vitamin B7 is not particularly susceptible to loss during cooking.
When cooking, it is important to use fresh food, steam rather than boil and avoid overly long cooking times to preserve vitamins.
Should I take a vitamin B7 supplement?
The Department of Health advises that you should get all the vitamin B7 you need by eating a healthy and balanced diet.
People on kidney dialysis or receive all their nutrition through a drip, may need a vitamin B7 supplement, but this must be checked with the relevant healthcare provider.
Research suggests vitamin B7 supplements may have a role to play in improving blood sugar levels in people with diabetes but more research needs to be done to confirm this.
Pregnant women with low levels of vitamin B7 may be advised to take vitamin B7 supplements.
Preliminary evidence suggests that vitamin B7 could help to strengthen brittle nails but the benefit is not proven.
Other uses of vitamin B7 supplements for conditions such as cradle cap, hair loss, depression and hepatitis have been untested.
However, if you take biotin supplements, do not take too much as this can be harmful.
Vitamin B7 supplement side effects
What are the side effects and safety precautions of taking a vitamin B7 supplement? Deficiency is rare and supplementation is not often required.
Vitamin B7 is deemed likely to be safe for most people when taken orally at the correct dosage. There isn’t thought to be any harm in taking up to 0.9mg daily.
What happens if I take too much vitamin B7?
Vitamin B7 is a water-soluble vitamin, which means that any excess is excreted in the urine and faeces making toxicity rare.
Little information is available regarding toxicity but if you are concerned that you may have overdosed on vitamin B7, then seek medical advice.
A condition called eosinophilic pleuropericardial effusion may result when excess vitamin B7 is ingested along with vitamin B5.
Do vitamin B7 supplements have any drug interactions?
Alcohol and some anti-convulsant drugs may affect the transport of biotin in the body.