A "vitamin" is also a pill that contains vitamins, eaten regularly to keep one healthy.
Fruits and vegetables are a source of vitamins

A vitamin is a chemical compound that is needed in small amounts for the human body to work correctly. They include Vitamin A, many B vitamins (like B1, B2, B3, B6, and B12), Vitamin C, Vitamin D, Vitamin E, and Vitamin K. For example, citrus fruits such as oranges and lemons contain vitamin C.

The term was coined in 1912 by biochemist Casimir Funk, who isolated a complex of micronutrients and proposed the complex be named vitamine.[1] By convention the word vitamin does not include other essential nutrients, such as certain minerals, essential fatty acids and essential amino acids.[2]

Thirteen vitamins are recognized at present. Vitamins are classified by their biological and chemical activity, and not their structure. Each vitamin name (the word vitamin followed by a letter) refers to a number of vitamer compounds which all show the same biological activity. For example, vitamin A refers to several different chemicals. Vitamers convert to the active form of the vitamin in the body. They are sometimes inter-convertible to one another as well.

The body does not make these chemicals. They come from other places, usually food. A short term lack of a certain vitamin is usually not a problem, because the body can store vitamins for a short time. Not having a certain vitamin for a longer period of time can lead to different diseases, depending on the vitamin. Probably the best-known of these diseases is scurvy, which results from not having enough Vitamin C. Beriberi and rickets are others.

Today, many drug companies make inexpensive pills that contain various vitamins. They help people avoid those diseases.

Vitamins can be either fat-soluble or water-soluble. Fat-soluble vitamins (A, D, E and K) can be stored in the body, and are used when needed.[3] Water-soluble ones only stay in the body a short time.

Name changes

Currently there are no vitamins F to J. These existed at some time. Today they are no longer seen as vitamins. Some of them were also false leads, and turned out to be something else. Others were renamed as B vitamins. Today, the B vitamins are a whole complex, and not just one vitamin.

The German-speaking scientists who isolated and described vitamin K (in addition to naming it as such) did so because the vitamin is intimately involved in the 'Koagulation' (clotting) of blood following wounding. At the time, most (but not all) of the letters from F through I were already designated, so the use of the letter K was considered quite reasonable. The following table lists chemicals that had previously been classified as vitamins, as well as the earlier names of vitamins that later became part of the B-complex.

Previous name[4][5] Chemical name[4][5] Reason for name change[4]
Vitamin B4 Adenine No longer classified as a vitamin
Vitamin B8 Adenylic acid No longer classified as a vitamin
Vitamin F Essential fatty acids Needed in large quantities (does
not fit the definition of a vitamin).
Vitamin G Riboflavin Reclassified as Vitamin B2
Vitamin H Biotin Reclassified as Vitamin B7
Vitamin J Catechol, Flavin No longer classified as a vitamin
Vitamin L1[6] Anthranilic acid No longer classified as a vitamin
Vitamin L2[6] Adenylthiomethylpentose No longer classified as a vitamin
Vitamin M Folic acid Reclassified as Vitamin B9
Vitamin O Carnitine No longer classified as a vitamin
Vitamin P Flavonoids No longer classified as a vitamin
Vitamin PP Niacin Reclassified as Vitamin B3
Vitamin U S-Methylmethionine No longer classified as a vitamin

List of vitamins

Vitamin generic
descriptor name
Active agent ('Vitamer') (list not complete) Solubility United States Recommended daily intake
(male, age 19–70)[7]
Deficiency disease Upper Intake Level
Overdose disease Food sources
Vitamin A Retinol, retinal, and
four carotenoids
including beta carotene
Fat 900 µg Night blindness, hyperkeratosis, and keratomalacia[8] 3,000 µg Hypervitaminosis A Liver, orange, ripe yellow fruits, leafy vegetables, carrots, pumpkin, squash, spinach, fish, soy milk, milk
Vitamin B1 Thiamine Water 1.2 mg Beriberi, Wernicke-Korsakoff syndrome N/D[9] Drowsiness or muscle relaxation with large doses.[10] Pork, oatmeal, brown rice, vegetables, potatoes, liver, eggs
Vitamin B2 Riboflavin Water 1.3 mg Ariboflavinosis, glossitis, angular stomatitis N/D Dairy products, bananas, popcorn, green beans, asparagus
Vitamin B3 Niacin, niacinamide, Nicotinamide riboside Water 16.0 mg Pellagra 35.0 mg Liver damage (doses > 2g/day)[11] and other problems Meat, fish, eggs, many vegetables, mushrooms, tree nuts
Vitamin B5 Pantothenic acid Water 5.0 mg[12] Paresthesia N/D Diarrhea; possibly nausea and heartburn.[13] Meat, broccoli, avocados
Vitamin B6 Pyridoxine, pyridoxamine, pyridoxal Water 1.3–1.7 mg Anemia[14] peripheral neuropathy 100 mg Impairment of proprioception, nerve damage (doses > 100 mg/day) Meat, vegetables, tree nuts, bananas
Vitamin B7 Biotin Water 30.0 µg Dermatitis, enteritis N/D Raw egg yolk, liver, peanuts, leafy green vegetables
Vitamin B9 Folates Water 400 µg Megaloblastic anemia and deficiency during pregnancy is associated with birth defects, such as neural tube defects 1,000 µg May mask symptoms of vitamin B12 deficiency; other effects. Leafy vegetables, pasta, bread, cereal, liver
Vitamin B12 Cyanocobalamin, hydroxocobalamin, methylcobalamin, adenosylcobalamin Water 2.4 µg Pernicious anemia[15] N/D Acne-like rash [causality is not conclusively established]. Meat, poultry, fish, eggs, milk
Vitamin C Ascorbic acid Water 90.0 mg Scurvy 2,000 mg Vitamin C megadosage Many fruits and vegetables, liver
Vitamin D Cholecalciferol (D3), Ergocalciferol (D2) Fat 10 µg[16] Rickets and osteomalacia 50 µg Hypervitaminosis D Fish, eggs, liver, mushrooms
Vitamin E Tocopherols, tocotrienols Fat 15.0 mg Deficiency is very rare; sterility in males and miscarriage in females, mild hemolytic anemia in newborn infants[17] 1,000 mg Increased congestive heart failure seen in one large randomized study.[18] Many fruits and vegetables, nuts and seeds
Vitamin K Phylloquinone, menaquinones Fat 120 µg Bleeding diathesis N/D Increases coagulation in patients taking warfarin.[19] Leafy green vegetables such as spinach, egg yolks, liver

Vitamin Media

Related pages


  1. Jr, Gerald F. Combs (2007-10-30). The Vitamins. Elsevier. ISBN 9780080561301.
  2. Maton, Anthea; Jean Hopkins; Charles William McLaughlin; Susan Johnson; Maryanna Quon Warner; David LaHart; Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. ISBN 0-13-981176-1. OCLC 32308337.
  3. NIcolas, AJ. "Facts about Vitamins".
  4. 4.0 4.1 4.2 Every Vitamin Page Archived 2007-02-06 at the Wayback Machine All Vitamins and Pseudo-Vitamins. Compiled by David Bennett.
  5. 5.0 5.1 "Vitamins and minerals - names and facts". Archived from the original on 2007-07-04. Retrieved 2007-03-31.
  6. 6.0 6.1 Michael W. Davidson (2004) Anthranilic Acid (Vitamin L) Florida State University. Accessed 20-02-07
  7. 7.0 7.1 Dietary Reference Intakes: Vitamins Archived 2016-03-28 at the Wayback Machine. The National Academies, 2001.
  8. "Vitamin A: Fact Sheet for Health Professionals". National Institute of Health: Office of Dietary Supplements. 5 June 2013. Archived from the original on 2009-09-23. Retrieved 2013-08-03.
  9. "Dietary Reference Intakes: Vitamins". The National Academies. 2001. Archived from the original on 2013-08-17. Retrieved 2018-04-29. Amount not determinable due to lack of data of adverse effects. Source of intake should be from food only to prevent high levels of intake.
  10. "Thiamin, vitamin B1: MedlinePlus Supplements". U.S. Department of Health and Human Services, National Institutes of Health.
  11. Hardman, J.G.; et al., eds. (2001). Goodman and Gilman's Pharmacological Basis of Therapeutics (10th ed.). p. 992. ISBN 0071354697.
  12. Plain type indicates Adequate Intakes (A/I). "The AI is believed to cover the needs of all individuals, but a lack of data prevent being able to specify with confidence the percentage of individuals covered by this intake" (see Dietary Reference Intakes: Vitamins Archived 2011-10-02 at the Wayback Machine. The National Academies, 2001).
  13. "Pantothenic acid, dexpanthenol: MedlinePlus Supplements". MedlinePlus. Retrieved 5 October 2009.
  14. Vitamin and Mineral Supplement Fact Sheets Vitamin B6 Archived 2009-09-23 at the Wayback Machine. (15 September 2011). Retrieved on 2013-08-03.
  15. Vitamin and Mineral Supplement Fact Sheets Vitamin B12 Archived 2009-09-23 at the Wayback Machine. (24 June 2011). Retrieved on 2013-08-03.
  16. Value represents suggested intake without adequate sunlight exposure (see Dietary Reference Intakes: Vitamins Archived 2011-10-02 at the Wayback Machine. The National Academies, 2001).
  17. The Merck Manual: Nutritional Disorders: Vitamin Introduction Please select specific vitamins from the list at the top of the page.
  18. Gaby, Alan R. (2005). "Does vitamin E cause congestive heart failure? (Literature Review & Commentary)". Townsend Letter for Doctors and Patients. Retrieved 2018-04-29. 
  19. Rohde LE; de Assis MC; Rabelo ER (2007). "Dietary vitamin K intake and anticoagulation in elderly patients". Curr Opin Clin Nutr Metab Care. 10 (1): 120–124. doi:10.1097/MCO.0b013e328011c46c. PMID 17143047. S2CID 20484616.