Vitamin B8 (or biotin) is a water-soluble vitamin also known as vitamin H. 

Biotin is a coenzyme that helps break down carbohydrates, certain amino acids, and fatty acids. Biotin also aids in the synthesis of vitamins B9 and B12. 

Roles

What does vitamin B8 do? 

  • Helps cells grow;
  • Assists in the production of fatty acids;
  • Metabolizes fats and amino acids (parts of proteins);
  • Plays a role in producing energy;
  • Helps maintain steady blood sugar levels.

Needs

Vitamin B8 doses are expressed in terms of adequate intake (AI) amounts, because data does not permit calculation of a recommended dietary allowance. There is generally little documentation regarding the amount of nutritionally available biotin: it is found in varying concentrations in a wide range of foods. Biotin is also produced naturally in the intestine by bacteria. 

Patients undergoing hemodialysis and peritoneal dialysis treatments (procedures that mechanically remove waste the kidneys are not able to excrete normally), and persons deficient in biotinidase are likely to require more biotin. 

Lacking sufficient data to determine a tolerable upper intake level (TUIL), individuals who consume nutrients in quantities that exceed the recommended adequate intake (AI) should exercise extreme care. 

Recommended Adequate Intake* (AI) for Vitamin B8: 

Age
Amount/Day in µg
Infants
0 to 6 months
5
7 to 12 months
6
Children
1 to 3 years
8
4 to 8 years
12
Preteens
9 to 13 years
20
Teens
14 to 18 years
25
Adults
19 years and up
30
Pregnant women
 
30
Nursing mothers
 
35

Source: DRI, Dietary Reference Intakes, The Essential Guide to Nutrient Requirements 2006, p.196.

*Lacking sufficient scientific evidence, authorities have established adequate intake (AI) amounts rather than recommended dietary allowances (RDAs). Adequate intake is based on observed average intakes in North Americans in good health.

Sources

Biotin is widely found in a variety of foods, but often in small amounts. The typical U.S. diet is estimated to provide approximately 40 µg of it per day. Royal jelly and brewers’ yeast are the only two foods that contain substantial quantities of biotin. The best natural human-grade food sources of biotin are liver, legumes, soy, Swiss chard, tomatoes, Romaine lettuce, and carrots. It is also found in almonds, eggs, onions, cabbage, cucumbers, cauliflower, goat milk, cow milk, raspberries, strawberries, halibut, oatmeal, and nuts. 

Food Sources for Vitamin B8: 

Foods
Portion Size
Vitamin B8
Cooked liver
85g
27-35µg
Cooked egg
1 large
13-25µg
Yeast
1 envelope (7g)
1.4-14µg
Cooked salmon
85g
4-5µg
Avocado
1 whole
2-6µg
Cooked pork
85g
2-4µg
Wholegrain bread
1 slice
0,02-6µg
Raw cauliflower
1 cup
0,2-4µg
Cheddar cheese
28g
0,4-2µg
Raspberries
1 cup
0,2-2µg

Deficiency

Biotin deficiency is relatively rare and harmless, and may be treated with supplements. This deficiency may be caused by excess consumption of raw egg whites (because of their elevated levels of avidin protein). Avidin binds tightly with biotin, thereby diminishing its absorption. Cooking alters avidin without affecting biotin. 

In children, genetically based metabolic anomalies may be behind biotin deficiency. This deficiency appears as changes in immune system function and in a heightened susceptibility to bacterial and fungal infections. 

Signs of vitamin B8 deficiency:

  • Skin inflammation and hypersensitivity (redness around the eyes, nose, and mouth);
  • Conjunctivitis;
  • Hair loss;
  • Absence or loss of pigment in the hair;
  • Muscle soreness;
  • Loss of appetite;
  • Nausea;
  • Neurological disorders (depression, fatigue, hallucinations, and tingling hands and feet);
  • Increase in blood cholesterol levels;
  • Decrease in blood hemoglobin, which could lead to anemia.

Adverse effects

No harmful effects have been tied to excessive biotin intake. 

Signs of excess vitamin B8:  

  • None.

Interactions

Natural health products or vitamin supplements: 

  • none; 

Drugs that may result in a vitamin B8 deficiency: 

  • Some antibiotics;
  • Some drugs used to treat epilepsy.

Additional information

Speak with your pharmacist if you plan to take vitamin B8 supplements. Your pharmacist can help you choose the solution that’s best for you based on your health and any drugs you take. 

Other names

Vitamin B8, Biotin, vitamin H