A substance having a chemical structure similar to that of a given vitamin, but lacking the usual physiologic action.
Farlex Partner Medical Dictionary © Farlex 2012


A substance that does not meet the accepted definition of a required human vitamin. Calling such substances vitamins is misleading, as they have no known therapeutic effects.

True vitamins are organic accessory food factors that usually remain in food after removal of the basic elements, including carbohydrates, fats, proteins, minerals, water and fibre, and are:  
(1) Necessary in trace amounts (daily intake in milligram to microgram quantities); and  
(2) Essential, as the body either does not produce them or does so in insufficient quantities.

Pseudovitamins, broad groups
• True vitamins not required in humans
• Substances once regarded as vitamins, but no longer regarded as such.
• “Factors”—in blood, exotic vegetables and fruits, or minerals—that have been termed "vitamins" by various persons.
• Metabolites, including intermediate metabolites (e.g., orotic acid—”vitamin B13”) and substances whose metabolism requires B vitamins (e.g., choline, inositol, methionine)
• Substances that are B vitamins for nonvertebrates—e.g., para-aminobenzoic acid, a B vitamin for certain bacteria (“vitamin Bx”) and carnitine, a B vitamin for mealworms (“vitamin Bt”).
• Pharmacologic substances—allegedly capable of favouring certain metabolic processes in humans, but which produce little if any objective improvement (e.g., flavonoids—“vitamin P”).
• Snake oil remedies (which meet the legal definition of fraud)—e.g., pangamate (“vitamin B15”), laetrile (“vitamin B17”) and gerovital (“vitamin H3”).

• Vitamin B3—Obsolete for pantothenic acid. 
• Vitamin B4—An ill-defined “factor” of uncertain validity, isolated from yeast or liver, said to alleviate myasthenia in animals; vitamin B4 “deficiency” responds to various agents, including adenine, arginine, cystine, glycine and thiamin.
• Vitamin B5—Obsolete for nicotinic acid (niacin) and nicotinamide.
• Vitamin B7:
   (1) Biotin;
   (2) Carnitine (permeability factor). 
• Vitamin B8—Adenylic acid (a nucleotide). 
• Vitamin B10—A growth and feather promoter in chickens, which corresponds to folic acid and vitamin B12. 
• Vitamin B11—A growth and feather promotor of chickens, similar or identical to vitamin B10. 
• Vitamin B13—Orotic acid, an intermediate in pyrimidine metabolism; it is not a vitamin. 
• Vitamin B15—Pangamate, a pseudovitamin with no known effects.
• Vitamin B17—Amygdalin (laetrile), a toxic substance claimed to be effective in treating malignancy.
• Vitamin Bc—Folic acid. 
• Vitamin Bp—A factor used to treat perosis in chickens, a condition that responds to a mixture of choline and manganese. 
• Vitamin Bt—An insect growth factor, identified as carnitine. 
• Vitamin Bw—Biotin. 
• Vitamin Bx—Para-aminobenzoic acid. 
• Vitamin C2—Bioflavinoids, substances with activities that partly overlap those of true vitamin C. 
• Vitamin F—Obsolete for essential fatty acids.
• Vitamin G—Obsolete for riboflavin. 
• Vitamin GH3—See Gerovital. 
• Vitamin H3—See Gerovital. 
• Vitamin H—Biotin (see there), a water-soluble factor with an uncertain role as a vitamin, which is a cofactor in enzymes catalysing carboxylation reactions (e.g., pyruvate carboxylase and acetyl CoA carboxylase); biotin deficiency is uncommon. 
• Vitamin I—Synonym for carnitine. 
• Vitamin J—Bioflavonoids.
• Vitamin L1—Anthranilic acid, a liver “factor” involved in lactation. 
• Vitamin L2—Adenylthiomethylpentose, a yeast “factor” involved in lactation. 
• Vitamin M—Folic acid. 
• Vitamin N—An anticarcinogenic preparation from the brain or stomach.
• Vitamin O—Synonym for supplementary oxygen.
• Vitamin P—Synonym for bioflavonoids. 
• Vitamin P4—Troxerutin. 
• Vitamin PP—Obsolete for nicotinic acid. 
• Vitamin R—A folic acid-related bacterial growth factor.  
• Vitamin S—A streptogenin-related protein that promotes growth in chicks. 
• Vitamin T—A mixture of amino acids, DNA nucleotides, folacin and vitamin B12, which promotes growth and healing in yeast and insects. 
• Vitamin U—Methylsulfonium salts of methionine, derived from cabbage juice, claimed to heal peptic ulcers.
• Vitamin V—A tissue “factor” composed of NAD+ and NADH+, which promotes bacterial growth.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.


A substance that does not meet the accepted definition of a required human vitamin
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The 25-hydroxyvitamin D1-[alpha]lpha-hydroxylase gene maps to the pseudovitamin D-deficiency rickets (PDDR) disease locus.
* Type I, sometimes known as pseudovitamin D-deficiency rickets, is due to defective production of 25(OH)[D.sub.3]-1-[alpha]-hydroxylase, an enzyme necessary for the conversion of calcidiol to calcitriol in the kidneys.
I presented the bottle to her and humbly asked, "What is in this that made me swim faster?" Rolling the bottle back and forth in her hands, like a safe cracker, she looked up and uttered "It was probably the PABA." This four-letter word resurrected several times in the years to follow, as a chemical I made in organic chemistry as an undergrad, as the photoprotectant in my sun block used over a decade of surfing, and as the pseudovitamin that I intentionally excluded from numerous multinutrient compositions that I formulated in my various corporate positions in the 1990s.
Pseudovitamin B(12) is the predominant cobamide of an algal health food, spirulina tablets.
Inactivating mutations in the 25-hydroxyvitamin D3 1alpha-hydroxylase gene in patients with pseudovitamin D-deficiency rickets.
No enzyme activity of 25-hydroxyvitamin D3 1alpha-hydroxylase gene product in pseudovitamin D deficiency rickets, including that with mild clinical manifestation.
The 25-hydroxyvitamin D 1-alpha-hydroxylase gene maps to the pseudovitamin D-deficiency rickets (PDDR) disease locus.
Novel mutations in the 1alpha-hydroxylase (P450c1) gene in three families with pseudovitamin D-deficiency rickets resulting in loss of functional enzyme activity in blood-derived macrophages.