Dietary sources biotin

Humans and other mammals do not synthesize the biotin that is brought from dietary source and from microorganisms of the normal micro flora colonizing the large intestine. In vivo studies have shown that the human large intestine is capable of absorbing installed biotin, but the contribution of biotin from microorganisms to the totally absorbed biotin has not been fully estabhshed and needs to be further clarified (Said 2009). 

Mock, D.M., 2004. Biotin physiology, dietary sources and requirements. In Caballero, B., Allen, L., and Prentice, A. (ed.) Encyclopaedia of Human Nutrition 2nd ed. Academic Press, London, UK 206-209. 

In the organism that Is required In small amounts In food to sustain the normal metabolic functions of life. The key to this definition Is that this chemical compound must be supplied to the organism because the animal cannot synthesize vitamins. Lack of It produces a specific deficiency syndrome and supplying It cures that deficiency. An exception to this definition Is vitamin D, which can be made In the skin upon adequate exposure to sunlight. However, without adequate exposure, the animal Is dependent on a dietary source. Biotin, panthothenlc acid, and vitamin R are made by bacteria In the human Intestine, based on a symbiotic relation-ship and, thus, are not required by the human. Niacin can also be synthesized In humans from the amino acid tryptophane. 

They are the major dietary source of vitamin B-12 and vitamin B-6, and they supply appreciable amounts of vitamin A, biotin, niacin, pantothenic acid, riboflavin, and thiamin. 

Biotin is widely distributed in foods. Beef liver, yeast, peanuts, kidney, chocolate, and egg yolk are especially rich sources. The intestinal flora synthesizes biotin. Fecal excretion reflects this enteric synthesis. Total daily urinary and fecal excretion exceeds the dietary intake. 

Sources Dietary Reference Intakes for Calcium, Phosphorous, Magnesium, Vitamin D, and Fluoride (1997) Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin Folate, Vitamin B, Pantothenic Acid, Biotin, and Choline (1998) Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids (2000) Dietary Reference hitakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc (2001) Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2002/2005) and Dietary Reference Intakes for Calcium and Vitamin D (2011). These reports may be accessed via www.nap.edu... 

The intervention of gastrointestinal proteases and peptidases transforms the protein bound forms of dietary biotin into biocytin or biotinyl-L-lysine and biotin-short peptides. In humans, it was assumed that biotinyl proteins and peptides arose from only two sources protein bound in food and degradation of endogenous biotin-containing carboxylases. 

Good sources of biotin are liver, pork, nuts, chocolate, pulses, cereals, and royal jelly, but biotin is widely distributed among all types of food and dietary deficiency is rare. However, biotin is inactivated by avidin which is present in raw egg whites and severe eczema has been reported from... 

Sources Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine Dietary Reference Intakes for calcium, phosphorus, magnesium, vitamin D and fluoride, 1997 Dietary reference intakes for thiamin, riboflavin, niacin, vitamin B, folate, vitamin Bj, pantothenic acid, biotin and choline, 1998 Dietary reference intakes for vitamin C, vitamin E, selenium and carotenoids, 2000 Dietary Reference Intakes for vitamin A, vitamin K, arsenc, boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium and zinc, 2001, National Academy Press Washington, DC. 

Biotin. Milk is a fairly good source of biotin, generally providing about 3 meg per 100 g. Two glasses of milk would provide between 7 and 23% of the average daily dietary intake of this vitamin. Less than 10% of biotin is destroyed by pasteurization. 

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