Biotin (Vitamin B7)

Vitamin B7 Test (Biotin in Serum)

Clinical Information

The role of biotin in the body is varied. It is an important cofactor and is involved in the metabolism of fatty acids and amino acids. Likewise, it plays a crucial role in the utilization of other B vitamins1.

Biotin is important for the maintenance of the hair, normal skin, and mucous membranes. It is also important for brain and nerve functions that determine concentration, learning, memory, and reasoning. However, claims on benefits of biotin on the maintenance of normal teeth, nails, reduction of tiredness and fatigue is not established2.

Signs and Symptoms of Deficiency or Toxicity

Signs and symptoms develop gradually. Some manifestations are thinning hair; scaly red rash around body openings such as the nose, mouth, and perineum; seizures; and brittle nails to name a few3.

Deficiency is rare3.

No established adverse effects3.

Biomarker and Methods of Analysis


Serum is a very good transport system for bound proteins to other tissues. It is more recommended than plasma which is not a sensitive marker of biotin status as it is shown to be resistant even with clinical signs of deficiency5, 6.

Supplementation Guide

No established clinical guidelines for supplementation.

No established upper limit but a suggested safety value of 2.5 mg7.

Dietary avidin binds to dietary biotin. Hence absorption is affected. Medications such as anticonvulsants also interact with biotin by increasing biotin catabolism4.

Food Sources

Most biotin in food is bound to protein3. Foods highest in biotin are organ meats, eggs, fish, meat, seeds, nuts, and potatoes4.

(1) Huskisson E, Maggini S, Ruf M. The role of vitamins and mineral in energy metabolism and well-being. The Journal of International Medical Research 2007; 35: 277-289
(2) European Food and Safety Authority Panel on Dieteic Products, Nutrition and Allergies (NDA). Scientific opinion on the substantiation of health claims related to biotin and maintenance of normal skin and mucous membranes (ID 121), maintenance of normal hair (ID 121), maintennace of normal bone (ID 121), maintenance of normal teeth (ID 121), maintenance of normal nails (ID 121, 2877), reduction of tiredness and fatigue (ID 119), contribution to normal psychological functions (ID 120) and contibution to normal macronutrient metabolism (ID 4661) pursuant to Article 13(1) of Regulation (EC) No 1924/2006. EFSA Jurnal 210; 8(10)1728.
(3) Office of Dietary Supplements-National Institutes of Health. Biotin. Fact Sheet for Health Professionals. Retrived from
(4) Higdon J, Drake VJ, Delage B. (July 2015). Micronutrient Information Center. Biotin. Retrieved from
(5) Mock DM, Lankford GL, Mock NI. Biotin accounts for only half of the total avidin-binding substances in human serum. The Journal of Nutrition 1995; 125(4):941-946.
(6) Grassl SM. Human placental brush-border membrane Na(+)-biotin cotransport. The Journal of Biological Chemistry 1992; 267(25): 17760-17765.
(7) Hathcock , John H. Safety of Vitamin and Minral Supplements. Safe Levels Identified by Risk Assessment. April 2004.