Former and Deprecated Vitamins: The Complete Reference
Over the last century, dozens of substances were given vitamin names — numbers like B4, B8, B13, B15 and B17, and letters from F to U. Most of them are no longer considered vitamins. Some were simply renamed; some turned out to be substances the body makes for itself; and a few were never vitamins at all, with names used mainly in marketing. This page is a plain-English map of the retired vitamin designations, what each substance actually is, and which page covers it in more depth.
Table of Contents
- What Actually Counts as a Vitamin
- Why a Substance Gets De-Listed
- The Four Fates of a Former Vitamin
- Deprecated B-Number Designations
- Deprecated Letter Vitamins
- Choline, Inositol, and the "B4 vs B8" Mix-Up
- Still Essential — Just Not Called "Vitamins"
- The "Vitamins" That Never Were
- Where These Substances Are Covered
- Key Research Papers
- Connections
- Featured Videos
1. What Actually Counts as a Vitamin
A vitamin is an organic compound that meets four conditions at once. It must be (1) organic (carbon-based, which separates vitamins from minerals like iron or zinc); (2) essential, meaning the body needs it for normal function; (3) something the body cannot make in adequate amounts on its own, so it has to come from the diet; and (4) linked to a specific deficiency disease that appears when it is missing and resolves when it is restored — scurvy for vitamin C, beriberi for thiamine, pellagra for niacin, rickets for vitamin D.
That fourth test is the strict one. When scientists in the early twentieth century found a new "accessory food factor," they often handed it a vitamin letter or B-number before its chemistry and biology were fully understood. As the science matured, many of those candidates failed one of the four tests — usually the "essential and cannot be self-synthesized" pair — and quietly lost their vitamin status. The names, however, lived on in old textbooks, supplement labels, and folk wisdom, which is why a question like "what is vitamin B17?" still comes up today.
2. Why a Substance Gets De-Listed
No single act retires a vitamin name. Nutrition scientists have at times formally proposed dropping a term — a 1950 note in Science was titled "Term 'vitamin P' recommended to be discontinued" (Vickery and colleagues) — but most old names simply fell out of use. Reclassification happens for a few recurring reasons:
- The body turns out to make it. Inositol and orotic acid are real, useful molecules, but humans synthesize them, so they are not dietary essentials. A substance the body can make in adequate amounts does not meet the definition of a vitamin.
- It was the same thing as a known vitamin. "Vitamin G" was riboflavin (B2); "vitamin H" was biotin (B7); "vitamin M" and "vitamin Bc" were folate (B9); "vitamin PP" was niacin (B3). These were renamed, not removed — they are still vitamins under their modern names.
- It belonged to a different nutrient class. "Vitamin F" is the essential fatty acids; they are genuinely essential, but they are fats, not vitamins.
- It never had a real identity or effect. "Pangamic acid" (B15) had no consistent chemical definition; "vitamin O" names no nutrient — the term has been used for "stabilized oxygen" products.
- It was harmful or discredited. "Laetrile" (B17) was promoted as a cancer cure, but it can release cyanide in the body and clinical study has not shown an anticancer benefit.
3. The Four Fates of a Former Vitamin
Almost every retired vitamin name lands in one of four buckets. Keeping these straight prevents two opposite mistakes — dismissing a genuinely essential nutrient because its "vitamin" status was revoked, and trusting a discredited product because it still wears a vitamin label.
- Renamed, still a vitamin. Same molecule, modern name. Examples: G → B2, H → B7, M → B9, PP → B3.
- Real, essential, but reclassified. Still important for health, just not categorized as a vitamin. Examples: choline (an essential nutrient), the essential fatty acids ("vitamin F").
- Real compound, not essential for humans. Exists and may have uses, but it is not needed in the diet because the body makes it or does not require it. Examples: inositol, PABA, orotic acid, ubiquinone (CoQ10), carnitine, alpha-lipoic acid, the bioflavonoids.
- Never a vitamin. No defined identity or no demonstrated benefit, and in one case a documented poisoning risk. Examples: pangamic acid ("B15"), laetrile/amygdalin ("B17"), "vitamin O".
4. Deprecated B-Number Designations
The B-complex was originally thought to be a single substance ("vitamin B") before it was separated into the eight true B vitamins recognized today (B1, B2, B3, B5, B6, B7, B9, B12). The gaps and high numbers below are the candidates that were proposed for membership and then dropped. The eight survivors keep their own pages under Vitamins.
| Old designation | Substance it referred to | Modern status | Covered on |
|---|---|---|---|
| Vitamin B4 | First an unidentified factor assayed at Oxford around 1930 (Reader); the label was later used for adenine and, in much nutrition literature, for choline (some secondary sources also list carnitine) | Adenine is a DNA/RNA base the body makes; choline is an essential nutrient but is not classed as a vitamin | Choline · Carnitine |
| Vitamin B8 | Inositol (myo-inositol) | Sugar alcohol the body synthesizes; sometimes called a "pseudovitamin" | Inositol |
| Vitamin B10 | PABA (para-aminobenzoic acid); also called Bx, H1. In 1940s chick research, "B10" and "B11" first named two folic-acid-related chick factors (Briggs and colleagues, 1944) | Bacterial folate precursor; not essential for humans | PABA |
| Vitamin B11 | A chick factor related to folic acid (Briggs and colleagues, 1944) | Folded into the folate story; not a separate vitamin | Vitamin B9 (Folate) |
| Vitamin B13 | Orotic acid | Pyrimidine intermediate the body makes; used as a mineral carrier | Orotic Acid |
| Vitamin B14 | A cell-proliferation factor reported by Norris and Majnarich in 1949 | Never validated as a vitamin | — |
| Vitamin B15 | "Pangamic acid" | No established identity (FDA Compliance Policy Guide 457.100); not a vitamin | Pangamic Acid |
| Vitamin B16 | Dimethylglycine (DMG) | Body makes it from choline/betaine; not essential | discussed under B15 |
| Vitamin B17 | Amygdalin / laetrile | Cyanogenic glycoside; not a vitamin; no anticancer benefit shown; fatal cyanide poisoning reported | Laetrile |
| Vitamin Bp | Choline | Essential nutrient, but classified as a nutrient, not a vitamin | Choline |
| Vitamin BT | Carnitine (an insect growth factor identified as carnitine in 1952) | Conditionally essential; body makes it from lysine & methionine | Carnitine |
| Vitamin Bm / Bx | Myo-inositol (Bm) and PABA (Bx) | Alternate names for B8 and B10 above | Inositol · PABA |
Several other fragments — Bv, Bw, and various single-study "factors" — appear in old literature without any consistent definition and are omitted here rather than reported as if they were real.
5. Deprecated Letter Vitamins
Before the alphabet was tidied up, vitamins were named roughly in order of discovery (A, B, C, D…). Several later letters were assigned to factors that were eventually merged into other vitamins, reclassified, or discarded.
| Old designation | Substance it referred to | Modern status | Covered on |
|---|---|---|---|
| Vitamin F | Essential fatty acids (linoleic & alpha-linolenic acid) | Genuinely essential, but they are fats, not vitamins | Omega-3 Fatty Acids |
| Vitamin G | Riboflavin | Renamed — still a vitamin | Vitamin B2 |
| Vitamin H | Biotin | Renamed — still a vitamin | Vitamin B7 |
| Vitamin J | No consistent identity in the old literature | Never validated as a vitamin | — |
| Vitamin L | "Lactation factors" described by Nakahara and colleagues (1938); anthranilic acid is the compound listed as vitamin L | Never validated as vitamins | — |
| Vitamin M | Folate (studied as "vitamin M" by Day; also called vitamin Bc, isolated as a chick anti-anaemia factor) | Renamed — still a vitamin | Vitamin B9 |
| Vitamin N | No consistent identity; some secondary sources list lipoic acid under this name | Not a vitamin; lipoic acid is made by the body and is not a dietary essential | Alpha-Lipoic Acid |
| Vitamin O | A name used for "stabilized oxygen" products | Not a vitamin; no nutrient by this name exists | — |
| Vitamin P | Flavonoids (rutin, hesperidin, quercetin), proposed in 1936 as a capillary "permeability" factor (Rusznyák and Szent-Györgyi) | Not a vitamin; the term was recommended for discontinuation in 1950 | Rutin · Hesperidin · Quercetin |
| Vitamin PP | Niacin / nicotinic acid (the "pellagra-preventive factor") | Renamed — still a vitamin | Vitamin B3 |
| Vitamin Q | Ubiquinone (Coenzyme Q10) | Not a vitamin; the body synthesizes it | CoQ10 |
| Vitamin S, T, U, W… | Vitamin U: the anti-ulcer factor of cabbage juice studied by Cheney (1949–1956), now identified as S-methylmethionine; vitamin T: a factor described by Goetsch in the 1940s; others such as "streptogenin" | None are recognized vitamins today; a 2026 review describes human evidence for S-methylmethionine as scarce | — |
6. Choline, Inositol, and the "B4 vs B8" Mix-Up
This pair causes more confusion than any other, so it is worth stating precisely. The label vitamin B4 was attached to more than one substance: an unidentified factor assayed around 1930, then adenine (French clinical papers of the 1950s wrote "adenine (vitamin B4)"), and choline, which nutrition papers still call "vitamin B4" (and some systems "vitamin Bp"). Inositol was the one designated vitamin B8, a label still used for myo-inositol. So the common belief that "choline used to be vitamin B8" swaps the two — choline's old number was B4; B8 belonged to inositol.
Both share the same modern fate: they are real, useful molecules that the body can synthesize, so neither meets the strict definition of a vitamin. Choline was officially recognized as an essential nutrient by the U.S. Institute of Medicine in 1998, which set an Adequate Intake for it, but it is not classed as a vitamin; inositol is sometimes described as a "pseudovitamin". Both have their own pages, with their historical vitamin numbers stated in each page's history section: Choline and Inositol (Vitamin B8). The choline / B4 story from the historical-designation angle is told on the Vitamin B4 page.
7. Still Essential — Just Not Called "Vitamins"
A retired vitamin name is not a verdict on the molecule. Two substances that lost the title are still dietary essentials:
- Choline (old vitamin B4 / Bp). Essential for the brain chemical acetylcholine, for cell membranes (as phosphatidylcholine), for liver fat metabolism, and for healthy pregnancy. The liver makes some choline, but not enough to cover the body's needs, which is why the Institute of Medicine recognized it as an essential nutrient in 1998; a 2009 review reports mean intakes for older children, men, women and pregnant women far below the Adequate Intake (Zeisel and da Costa). See Choline.
- Essential fatty acids (old vitamin F). Omega-3 and omega-6 fats are true dietary essentials; in Burr and Burr's 1929 experiments, removing fat from the diet of rats produced a deficiency disease. They are categorized as fats rather than vitamins. See Omega-3 Fatty Acids.
Several "fate 3" compounds — CoQ10, carnitine, alpha-lipoic acid, and the bioflavonoids — are not dietary essentials but remain subjects of research. Each is covered in the section that matches its chemistry rather than under Vitamins.
8. The "Vitamins" That Never Were
Two former vitamin names carry particular safety and accuracy questions, and both names still circulate:
- Pangamic acid ("vitamin B15"). There is no agreed chemical definition of pangamic acid; products sold under the name have contained different substances. The U.S. Food and Drug Administration's Compliance Policy Guide Sec. 457.100 (first issued in 1976) states that no identity has been established for a substance called pangamic acid, that no accepted scientific evidence establishes its nutritional properties or a deficiency in people or animals, and that products promoted for disease are unapproved new drugs; it names seizure as the primary initial enforcement action. See Pangamic Acid.
- Laetrile / amygdalin ("vitamin B17"). Promoted as a natural cancer cure, it is not a vitamin. In a 1982 clinical trial sponsored by the U.S. National Cancer Institute, 178 people with cancer received amygdalin plus a "metabolic therapy" program; no substantive benefit was seen in cure, stabilization, symptoms or survival, and several patients showed symptoms of cyanide toxicity or blood cyanide levels approaching the lethal range (Moertel and colleagues, New England Journal of Medicine). A 2015 Cochrane review found no randomized trials that met its criteria, reported a considerable risk of serious cyanide poisoning, especially after oral ingestion, and judged the risk–benefit balance "unambiguously negative." Fatal cyanide poisoning after laetrile or amygdalin was reported in 1977 and 1979. See Laetrile.
Both terms are still widely searched; the linked pages set out the regulatory record and the published evidence for each.
9. Where These Substances Are Covered
A "vitamin-related" substance can belong to several chemical classes, so each is filed with its class and cross-linked:
- Former vitamins with no better home — PABA, orotic acid, pangamic acid, laetrile, choline, inositol — live here under Vitamins, each clearly labeled with its retired designation.
- Amino-acid–derived compounds — carnitine, taurine, creatine — live under Amino Acids.
- Antioxidant cofactors and polyphenols — CoQ10, alpha-lipoic acid, PQQ, the flavonoids — live under Antioxidants.
- Essential fats live under Food.
This page serves as the index linking each old name to the substance it referred to and to the page that covers it.
Key Research Papers
- Semba RD. The Discovery of the Vitamins. International Journal for Vitamin and Nutrition Research, 2012;82(5):310–315. — doi:10.1024/0300-9831/a000124
- Carpenter KJ. A Short History of Nutritional Science: Part 1 (1785–1885). The Journal of Nutrition, 2003;133(3):638–645. — doi:10.1093/jn/133.3.638 (Editorial note: Part 1 covers the period before vitamins were named; the vitamin era is in Part 3, below.)
- Rusznyák S, Szent-Györgyi A. Vitamin P: Flavonols as Vitamins. Nature, 1936;138:27. — doi:10.1038/138027a0
- Herbert V. Pangamic acid ("vitamin B15"). The American Journal of Clinical Nutrition, 1979;32(7):1534–1540. — doi:10.1093/ajcn/32.7.1534 (PubMed PMID: 377937)
- U.S. Food and Drug Administration. CPG Sec. 457.100 — Pangamic Acid and Pangamic Acid Products Unsafe for Food and Drug Use. FDA Compliance Policy Guide.
- National Cancer Institute. Laetrile/Amygdalin (PDQ®) — Health Professional Version. cancer.gov.
- Reader V. The assay of vitamin B4. Biochemical Journal, 1930;24(6):1827–1831. — PubMed PMID: 16744538
- Lecoq R. [The role of adenine (vitamin B4) in the metabolism of organic compounds and its repercussions on acid-base equilibrium]. Journal de Physiologie (Paris), 1954;46(1):406–410. — PubMed PMID: 13192701
- Łoboś P, Regulska-Ilow B. Link between methyl nutrients and the DNA methylation process in the course of selected diseases in adults. Roczniki Państwowego Zakładu Higieny, 2021;72(2):123–136. — PubMed PMID: 34114759
- Sheludchenko MS, Kovalenko EV, Shoshina OO, Odintsova VE, Koshechkin SI, Volokh OI. Peptidome and Metabolome Profiling of Fermented Milk Products Reveal Accumulation of Bioactive Compounds During Cold Storage. Current Issues in Molecular Biology, 2026;48(9):955. — PubMed PMID: 42793311
- Briggs GM Jr, Luckey TD, Elvehjem CA, Hart EB. Further studies on vitamins B10 and B11 and their relation to "folic acid" activity. Journal of Biological Chemistry, 1944;153:423–434. — doi:10.1016/s0021-9258(18)71984-4
- Calvo L, Rodríguez J, Vinagre F, Sánchez A. Determination of orotic acid (vitamin B13) in human serum and urine by differential-pulse polarography. Analyst, 1988;113(2):321–323. — PubMed PMID: 3377175
- Norris ER, Majnarich JJ. Vitamin B14 and cell proliferation. Science, 1949;109(2820):32–33. — PubMed PMID: 17760063
- Carter HE, Bhattacharyya PK, Weidman KR, Fraenkel G. Chemical studies on vitamin BT isolation and characterization as carnitine. Archives of Biochemistry and Biophysics, 1952;38:405–416. — PubMed PMID: 12997117
- Sherman HC, Ellis LN. Responses to different levels of nutritional intake of riboflavin (formerly called vitamin G). Proceedings of the National Academy of Sciences USA, 1939;25(8):420–422. — PubMed PMID: 16577926
- Eakin RE, McKinley WA, Williams RJ. Egg-white injury in chicks and its relationship to a deficiency of vitamin H (biotin). Science, 1940;92(2384):224–225. — doi:10.1126/science.92.2384.224
- Day PL. The evolution of vitamin M (folic acid). Journal of the Arkansas Medical Society, 1948;44(12):253–257. — PubMed PMID: 18912881
- Pfiffner JJ, Binkley SB. Isolation and characterization of vitamin Bc from liver and yeast; occurrence of an acid-labile chick antianemia factor in liver. Journal of the American Chemical Society, 1947;69(6):1476–1487. — PubMed PMID: 20249738
- Nakahara W, Inukai F, Ugami S. Vitamin L. Science, 1938;87(2260):372–373. — PubMed PMID: 17808589
- Wang Y, Okabe N. Crystal structures and spectroscopic properties of zinc(II) ternary complexes of vitamin L, H' and their isomer m-aminobenzoic acid with bipyridine. Chemical & Pharmaceutical Bulletin, 2005;53(6):645–652. — PubMed PMID: 15930776
- Vickery HB, Nelson EM, Almquist HJ, Elvehjem CA. Term "vitamin P" recommended to be discontinued. Science, 1950;112(2917):628. — PubMed PMID: 14787488
- Karlsson J, Semb B. Heart muscle and plasma vitamin Q with heart transplantation. Canadian Journal of Cardiology, 1997;13(2):147–152. — PubMed PMID: 9070166
- Goetsch W. Ein neuentdeckter Wirkstoff (Vitamin-T-Komplex). Experientia, 1947;3(8):326–327. — doi:10.1007/bf02164247
- Cheney G. Anti-peptic ulcer dietary factor (vitamin "U") in the treatment of peptic ulcer. Journal of the American Dietetic Association, 1950;26(9):668–672. — PubMed PMID: 15436263
- Ananian AA, Zelenina TZ, Stepanova OI, Popova AA, et al. S-Methylmethionine (Vitamin U): A Critical Narrative Review of Pharmacological Mechanisms, Evidence Levels, and Translational Barriers. Pharmaceuticals (Basel), 2026;19(5):743. — PubMed PMID: 42198417
- Burr GO, Burr MM. A new deficiency disease produced by the rigid exclusion of fat from the diet. Journal of Biological Chemistry, 1929;82:345–367; reprinted as a Nutrition Classic in Nutrition Reviews, 1973;31(8):248–249 (the reprint is the PubMed record). — PubMed PMID: 4586201
- Zeisel SH, da Costa KA. Choline: an essential nutrient for public health. Nutrition Reviews, 2009;67(11):615–623. — PubMed PMID: 19906248
- Carpenter KJ. A short history of nutritional science: part 3 (1912–1944). The Journal of Nutrition, 2003;133(10):3023–3032. — PubMed PMID: 14519779
- Moertel CG, Fleming TR, Rubin J, Kvols LK, Sarna G, Koch R, Currie VE, Young CW, Jones SE, Davignon JP. A clinical trial of amygdalin (Laetrile) in the treatment of human cancer. New England Journal of Medicine, 1982;306(4):201–206. — PubMed PMID: 7033783
- Milazzo S, Horneber M. Laetrile treatment for cancer. Cochrane Database of Systematic Reviews, 2015;(4):CD005476. — PubMed PMID: 25918920
- Humbert JR, Tress JH, Braico KT. Fatal cyanide poisoning: accidental ingestion of amygdalin. JAMA, 1977;238(6):482. — PubMed PMID: 577571
- Braico KT, Humbert JR, Terplan KL, Lehotay JM. Laetrile intoxication. Report of a fatal case. New England Journal of Medicine, 1979;300(5):238–240. — PubMed PMID: 759871
- Further reading on each substance and its citations: see the individual pages linked in the tables above.
Connections
- All Vitamins
- Former vitamins on this site: PABA (B10), Orotic Acid (B13), Pangamic Acid (B15), Laetrile (B17)
- Choline (former vitamin B4 / Bp)
- Inositol (former vitamin B8)
- Vitamin B4 (the choline / B4 story)
- Vitamin B9 (Folate — old vitamin M / B11)
- Vitamin B2 (Riboflavin — old vitamin G)
- Vitamin B3 (Niacin — old vitamin PP)
- Vitamin B7 (Biotin — old vitamin H)
- Carnitine (old vitamin BT)
- CoQ10 (old vitamin Q)
- Alpha-Lipoic Acid (old vitamin N)
- Omega-3 Fatty Acids (old vitamin F)