Polarized light micrograph of D-biotin (vitamin H, coenzyme R, or vitamin B7) crystals, a coenzyme used in cell growth, the production of fatty acids, the metabolism of fats and amino acids, and in the biotechnology industry to conjugate proteins for biotinylation. It plays a role in the Krebs cycle, in gluconeogenesis, and in maintaining a steady blood sugar level. Biotin occurs bound to proteins or polypeptides, and is abundant in liver, pancreas, kidney, yeast, and milk. It relieves progressive multiple sclerosis disease. Biotin deficiency, a rare nutritional disorder, can become fatal if untreated. Biotin supplementation is recommended during pregnancy and for strengthening hair and nails. It is found in many cosmetic and health products for the hair and skin. Field of view size: 0.740 x 1.110 mm (0.0291 x 0.0437 in)