Vitamin B7 – Biotin – What Is It?


Chemical structure of biotin

Vitamin B7 is also known as biotin, vitamin H or coenzyme R.  Biotin is a water-soluble vitamin that takes part in reactions that add carbon dioxide to compounds.  This vitamin is absorbed in the small intestine and what little is stored in the body is stored in the muscles, liver, and brain.  It is believed that intestinal bacteria synthesize at least some of the biotin that our bodies need as humans excrete more biotin than we consume.

What Does It Do?

Biotin is an essential co-factor for five enzymes that are responsible for the metabolism of carbohydrates, amino acids, and fatty acids.  Specifically, it is involved in gluconeogenesis (making glucose from non-carbohydrates sources, such as fatty acids and proteins) and the synthesis of fatty acids and certain amino acids (isoleucine and valine).  It is also involved in cell growth and the breakdown of branched chain amino acids.  Without this vitamin, there would be a decrease in aerobic respiration as biotin is involved in the citric acid cycle.

Where Can You Find It?

biotin-foodsDifferent quantities of biotin can be found in a wide variety of foods.  Sources rich in biotin include peanut butter, whole grains, milk, salmon, eggs and cheeses.

How Much Do You Need?

Due to insufficient information regarding how much biotin we need on a daily basis, there are no RDAs for biotin.  However, the Adequate Intake (AIs) for biotin is shown below:


Adequate Intake
Infants and children
0-6 months

5   mcg

7-12 months

6   mcg

1-3 years

8   mcg

4-8 years

12   mcg

9-13 years

20   mcg

Adolescents, 14-18 years

25   mcg

Adults, 19+

30   mcg


30   mcg


35   mcg

What Happens If You Don’t Get Enough?

Biotin Deficiency

Red rash around eyes, nose, and mouth associated with biotin deficiency

A protein in raw egg whites (avidin) can bind to biotin and prevent its absorption.  Symptoms of deficiency have been found in people who eat as few as three raw egg whites a day.  Chronic alcoholism may also lead to biotin deficiency.  There are a few inherited disorders where the enzymes that use biotin cannot properly utilize this vitamin.  These are called multiple carboxylase deficiency disorders.

Symptoms of biotin deficiency include hair loss (alopecia); pink eye (conjunctivitis); a red, scaly rash around the eyes, mouth, and nose; depression; listlessness; hallucinations; weight loss; anorexia; muscle pain; and tingling in the arms and legs.

What Happens If You Take Too Much?

Current research suggests that there are no adverse effects from the intake of too much biotin.  Since it is a water-soluble vitamin, excess amounts are excreted in urine.  Therefore, there is no Upper Tolerable Limit for biotin.

Bottom Line

The best way to consume any nutrient in order to avoid under-consumption is to consume a wide variety of foods, in a wide variety of colors, and eat according to MyPlate.

Until next time, remember that… there are no excuses when it comes to your health!


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