Many of the following substances have been referred to as vitamins because they were believed to be vitamins at one time. They are not considered vitamins anymore 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: adenine, a nucleobase, is synthesized by the human body.
Vitamin B7: is also known as “vitamin I” of Centanni E. (1935)-also called “Enteral factor”-is a water and alcohol-soluble rice-bran factor that prevents digestive disturbance in pigeons. It governs the anatomical and functional integrity of the intestinal tract. Later found in yeast. Possible candidates for this substance are inositol, niacin (nicotinic acid), and biotin. Carnitine was also claimed to be a candidate but is not soluble in alcohol. Ref: Biochim, e terap. sper. 22:137 (April 30)1935 E. Centenni. Presse med. 51 No6 66-7 1943 R. Jacquot (on enteral B7 in Yeast) et. al.
Vitamin B8: adenosine monophosphate, or alternately myo-inositol, is synthesized by the human body.
Vitamin B10: para-aminobenzoic acid (PABA)
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; also known as vitamin S or factor S.
Vitamin B13: orotic acid, now known not to be a vitamin.
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
Vitamin B16: dimethylglycine (DMG)
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 accepted scientific evidence.
Vitamin B20: carnitine
Vitamin B22: often claimed as an ingredient of Aloe vera extracts but also in many other foods. Claimed by one source to be vitamin B12b-?.
Vitamin Bh: biotin
Vitamin Bm: “mouse factor”: also used to designate inositol
Vitamin Bp: choline[dubious – discuss] Choline is only required for survival of some mutants. Most commonly it is synthesized in vivo de novo. May be added as supplement especially when methionine supply is limited[why?]
Vitamin Bt: L-carnitine
Vitamin Bv: a type of B6 but not pyridoxine[clarification needed]
Vitamin Bw: a type of biotin but not d-biotin[clarification needed]
Vitamin Bx: para-aminobenzoic acid
Note: B16, B17, B18, B19, B20, B21 & B22 do not appear to be animal factors but are claimed by some naturopaths as human therapeutic factors.[citation