The history of vitamins is surely an interesting one. I still don’t know much about it but I do know that there were a lot of vitamins that were labeled that no longer “make the cut”. This is often either because the vitamins became reclassified or they were found to be synthesized by the human body thus not essential to obtain from the diet. On this latter point, just because something can be synthesized from the body does not mean such synthesis is optimal. So paying attention to what substances received a label of being a vitamin still offers clues to important nutritional factors for humans. In this list only vitamins K1 and K2 are still considered vitamins.
- Vitamin B4 – adenine, found in nature linked to B1 but not included with synthetic B1, the human anti-paralysis factor, may play a role in preventing congestive heart failure
- Vitamin B8 – inositol, common in food and stored in relatively high levels in the human body, stores can be depleted by caffeine use, depletion of stores may lead to skin, hair, and eye problems, as well as constipation
- Vitamin F – essential fatty acids linoleic acid (LA, an omega-6) and alpha linolenic acid (ALA, an omega-3), was considered a vitamin from roughly 1923 until 1930 then reclassified as fatty acids.
- Vitamin G – riboflavin, reclassified as B2, the “G” complex has many property differences from the “B” complex
- Vitamin K1 – blood clotting factor in humans
- Vitamin K2 – calcium transport factor in humans
- Vitamin P (P for permeability) – bioflavonoids, capillary permeability factor, anti-oxidant properties, vitamin designation from the 1930’s until the 1950’s
- Vitamin PP – niacin, reclassified as B3
- Vitamin U (U for ucler) – the anti-ulcer factor found in cabbage, an enzyme, never officially designated as a vitamin
- The other B Vitamins – Wikipedia has a list of the missing B Vitamins
- Some details on these and others (H, J, L1, L2, M, O, S) can be found at Wikipedia on this list of reclassified vitamins