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Many of the following substances have been referred to as vitamins as they were once believed to be vitamins. They are no longer considered as such, and the numbers that were assigned to them now form the "gaps" in the true series of B-complex vitamins described above (e.g., there is no vitamin B4). Some of them, though not essential to humans, are essential in the diets of other organisms; others have no known nutritional value and may even be toxic under certain conditions. Vitamin B4: can refer to the distinct chemicals choline, adenine, or carnitine.[35][36] Choline is synthesized by the human body, but not sufficiently to maintain good health, and is now considered as an essential dietary nutrient.[37] Adenine is a nucleobase synthesized by the human body.[38] Carnitine is an essential dietary nutrient for certain worms, but not for humans.[39] Vitamin B8: adenosine monophosphate (AMP), also known as adenylic acid.[40] Vitamin B10: para-aminobenzoic acid (pABA or PABA), a chemical component of the folate molecule produced by plants and bacteria, and found in many foods.[41][42] It is best known as a UV-blocking sunscreen applied to the skin, and is sometimes taken orally for certain medical conditions.[41][43] Vitamin B11: pteryl-hepta-glutamic acid—chick growth factor, which is a form of folic acid. Later found to be one of five folates necessary for humans. Vitamin Bc-conjugate was also found to be PHGA. Vitamin B13: orotic acid.[44] Vitamin B14: cell proliferant, anti-anemia, rat growth factor, and antitumor pterin phosphate named by Earl R. Norris. Isolated from human urine at 0.33ppm (later in blood), but later abandoned by him as further evidence did not confirm this. He also claimed this was not xanthopterin. Vitamin B15: pangamic acid,[44] also known as pangamate. Promoted in various forms as a dietary supplement and drug; considered unsafe and subject to seizure by the US Food and Drug Administration.[45] Vitamin B16: dimethylglycine (DMG)[46] is synthesized by the human body in the Citric acid (or Kreb) cycle. Vitamin B17: nitrilosides, amygdalin or Laetrile. These substances are found in a number of seeds, sprouts, beans, tubers, and grains. While toxic in large quantities, proponents claim that it is effective in cancer treatment and prevention despite a lack of scientific evidence.[47] Vitamin B20: L-carnitine.[46] Vitamin Bf: carnitine.[40] Vitamin Bm: myo-inositol, also called “mouse antialopaecia factor”.[48] Vitamin Bp: “antiperosis factor”, which prevents perosis, a leg disorder, in chicks; can be replaced by choline and manganese salts.[39][40][49] Vitamin BT: carnitine.[50][39] Vitamin Bv: a type of B6 other than pyridoxine. Vitamin BW: a type of biotin other than d-biotin. Vitamin Bx: an alternative name for both pABA (see vitamin B10) and pantothenic acid.[39][43] |
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