What is biotin (vitamin B7)?

Biotin was once known as B7 or vitamin H. It is one of 8 vitamins that belong to the B group and, like the others, is used in many of the body’s biochemical systems. Biotin is found in a variety of plant and animal foods, but is also produced by the friendly bacteria that normally live in our intestines.

What does biotin do in the body?

Biotin performs a number of important functions. It:

• is essential for the activity of four key enzymes in the body
• metabolises protein and fat
• aids growth
• nourishes nerve cells.

How much biotin do I need?

The Adequate Intakes^* (AIs) for biotin per day are:

Infants

5 μg for infants (0-6 months)

6 μg for infants (7-12 months)

Children

8 μg for children (1-3 years)

12 μg for children (4-8 years)

20 μg for children (9-13 years)

Older children

25 μg for girls (14-18 years)

30 μg for boys (14-18 years)

Women

25 μg for women (18 years and over)

30 μg during pregnancy

35 μg during lactation

Men

30 μg for men (18 years and over )

μg means micrograms which is smaller than milligrams.

^*There are no RDIs for biotin as there are with better-known vitamins so an Adequate Intake (AI) figure is given instead.

Source: NHMRC Australia New Zealand 2006, Nutrient Reference Values

Safe upper limit for biotin

We don’t yet have sufficient evidence of ill effects to warrant the setting of an upper limit. Having said this, there are no known toxic symptoms from excess biotin as it’s water-soluble with excess being washed out in the urine and so it’s unlikely that levels of intake higher than the AIs would be associated with adverse health effects.

List of the best biotin-rich food sources

Biotin is a vitamin not widely reported in food composition tables and its availability is not well known for most foods. However, as it’s usually found in the company of other B group vitamins foods that are good sources of all the B vitamins will be good for biotin e.g. egg yolk, organ meats (liver, kidney, heart), yeast, oats, whole grains, legumes and nuts.

My top 20 sources

Here’s a list of the 20 richest food sources of biotin by concentration by weight per 100g (3½oz) in descending order:

1. Liver
2. Dried yeast
3. All nuts but especially peanuts, hazelnuts, almonds, pistachios
4. Instant coffee
5. Brans such as wheat bran, rice bran, oat bran
6. Liquorice
7. Sundried tomatoes
8. Yeast spread e.g. Vegemite, Marmite
9. Worcestershire sauce
10. Rolled oats and oat bran cereals
11. Sunflower seeds
12. Wheat germ
13. Wheat bran cereal and wholewheat biscuit breakfast cereals
14. Cocoa powder
15. Mushrooms
16. Tahini (sesame seed paste)
17. Soy beans, split peas, lentils and other legumes
18. Wholemeal wheat and rye flour
19. Pearl barley
20. Broccoli

Source: FSANZ  NUTTAB 2010 database

Easy ways get your recommended day's intake

The best way to get your daily biotin requirement is to eat a balanced diet that contains a variety of foods. But here are some easy ways to reach the goal of 25 to 30μg a day: 

Source: FSANZ NUTTAB 2010 database

Biotin deficiency signs

Biotin deficiency is rare mainly because the daily requirement for biotin is low and many foods provide adequate amounts of it. Also our natural intestinal bacteria actually synthesize small amounts of it.

Deficiency has been identified in people who have been tube fed with a biotin-free mixture (parenteral nutrition) over long periods of time. Deficiency is also seen in rare genetic disorders such as biotinidase deficiency.

Here are the tell-tale signs of biotin deficiency:

• Dermatitis and rashes
• Conjunctivitis
• Loss of hair or total baldness (alopecia)
• Severe malnutrition
• Central nervous system abnormalities (depression, lethargy, hallucinations and burning or prickling sensations in the extremities) including developmental delay in babies.

Interesting facts about biotin

Although rare, deficiency of biotin has been noticed in people who consume a lot of raw egg whites over long periods of time. One case study involved an 11-year-old boy who ate a large number of raw egg whites. Doses of biotin and the removal of raw eggs from the diet led to the reversal of all of the symptoms observed, including his total hair loss and skin disease.

Egg white contains high levels of avidin, a natural protein that binds to biotin strongly. When cooked, avidin is partially denatured which reduces the binding and so cooked egg whites are not a problem.