Spherulitic crystallites of the important vitamin biotin (vitamin H) acquire a pseudo three-dimensional appearance when photographed under a combination of polarized light and Hoffman modulation contrast. The photomicrograph below was taken using this combination in addition to a first-order retardation placed between the specimen and the analyzer at a 45-degree angle to the vibration directions of the polarizer and analyzer.

Biotin is a water-soluble member of the B-complex group of vitamins and is commonly referred to as vitamin H. The biochemical acts as a carrier for carbon dioxide in the pyruvate carboxylase reaction, where biotin is linked to the epsilon-amino group of a lysine residue in the enzyme. Biotin is necessary for both metabolism and growth in humans, particularly with reference to production of fatty acids, antibodies, digestive enzymes, and in niacin (vitamin B-3) metabolism. Food sources for biotin are liver, kidney, soy flour, egg yolk, cereal, and yeast. There are suggestions that biotin is also capable of curing baldness, alleviating muscle pain and depression, and functions as a cure for dermatitis, although there is no substantial evidence for any of these claims. Biotin deficiency results in fatigue, depression, nausea, muscle pains, hair loss, and anemia.

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