Vitamin B7 deficiency is a condition caused by the lack of biotin in the body.
Biotin, also known as vitamin B7 or vitamin H, is a vitamin found in food. It is one of 8 vitamins of the group B.
Biotin is involved in the cell growth, the production of fatty acids and the metabolism of fats and amino acids. Biotin is a coenzyme in several ferments such as Acetyl-CoA carboxylase alpha, Acetyl-CoA carboxylase beta, Methylcrotonyl-CoA carboxylase, Propionyl-CoA carboxylase, Pyruvate carboxylase. All of these enzymes are carboxylase enzymes required for the fatty acid synthesis, amino acid catabolism and gluconeogenesis.
The current adequate intakes for biotin are:
for adults ages 19 and up – 30 μg/day;
for pregnancy – 30 μg/day;
for lactation 35 μg/day;
for infants up to 12 months – 5-6 μg/day
for children ages 1–18 years increases with age from 8 to 25 μg/day.
The low requirement for biotin determines the rare incidence of biotin deficiency.
The best sources of biotin are:
Causes and risk factors
There is a bunch of rare metabolic disorders in which an individual’s metabolism of biotin is abnormal. One of them is the deficiency in the holocarboxylase synthetase enzyme (which links biotin onto the carboxylase, where the biotin is needed as a cofactor).
Raw egg whites contain a protein called avidin that interferes with the absorption of biotin, therefore people who regularly consume eggs in large amounts may become biotin-deficient.
People who consume alcohol are also at risk of developing the biotin deficiency. There are several conditions when the consumption of biotin in the body is increased or its absorption decreases. These are such conditions as a partial gastrectomy or have other disorders accompanied by achlorhydria, burns, epilepsy, smoking, pregnancy and lactation. Athletes and the elderly have a higher requirement of biotin as well.
Biotin deficiency is common for people who get total parenteral nutrition without biotin supplementation. A shortage of proteins involved in biotin homeostasis can cause biotin deficiency.
Some anti-convulsant medications (phenytoin, primidone, and carbamazepine) interfere with the transport of biotin through the mucous membranes.
See also: Vitamin F deficiency
Biotin deficiency usually develops when a person’s diet doesn’t contain an adequate amount of vitamin.
Signs and symptoms of vitamin B7 deficiency include:
Hair loss (alopecia) and fine hair;
Conjunctivitis and dry eyes;
Dermatitis in the form of a scaly, red rash around the eyes, nose, mouth, and genital area, cracked lips;
Loss of appetite;
Fatigue and insomnia;
Neurological symptoms such as depression, lethargy, hallucinations, and numbness and tingling of the extremities (paresthesias);
Increased susceptibility to infections (especially fungal) due to poor immunity;
The level of biotin in the body can be measured by the excretion of 3-hydroxyisovaleric acid and biotin in urine and the activity of propionyl-CoA carboxylase in lymphocytes.
Biotin supplements are used to treat the condition.