B vitamins

List of B vitamins

Note: Other substances once thought to be vitamins were given B-numbers, but were disqualified once discovered to be either manufactured by the body or not essential for life. See for numbers 4, 8, 10, 11, and others.

Sources

B vitamins are found in abundance in meat, eggs, and dairy products.

Sources for B vitamins also include spinach, legumes (pulses or beans), whole grains, asparagus, potatoes, bananas, chili peppers, breakfast cereals. The B12 vitamin is not abundantly available from plant products (although it has been found in moderate abundance in fermented vegetable products, certain seaweeds, and in certain mushrooms, with the bioavailability of the vitamin in these cases remaining uncertain), making B12 deficiency a legitimate concern for those maintaining a vegan diet. Manufacturers of plant-based foods will sometimes report B12 content, leading to confusion about what sources yield B12. The confusion arises because the standard US Pharmacopeia (USP) method for measuring the B12 content does not measure the B12 directly. Instead, it measures a bacterial response to the food. Chemical variants of the B12 vitamin found in plant sources are active for bacteria, but cannot be used by the human body. This same phenomenon can cause significant over-reporting of B12 content in other types of foods as well.

A common way to increase vitamin B intake is by using dietary supplements. B vitamins are commonly added to energy drinks, many of which have been marketed with large amounts of B vitamins.

Because they are soluble in water, excess B vitamins are generally readily excreted, although individual absorption, use and metabolism may vary. The elderly and athletes may need to supplement their intake of B12 and other B vitamins due to problems in absorption and increased needs for energy production. In cases of severe deficiency, B vitamins, especially B12, may also be delivered by injection to reverse deficiencies. Both type 1 and type 2 diabetics may also be advised to supplement thiamine based on high prevalence of low plasma thiamine concentration and increased thiamine clearance associated with diabetes. Also, folate deficiency in early embryo development has been linked to neural tube defects. Thus, women planning to become pregnant are usually encouraged to increase daily dietary folate intake or take a supplement.

Molecular functions

To the right, a diagram of some of the major B vitamins (2, 3, 5, 9, and 12) are shown as precursors for certain essential biochemical reactants (FAD, NAD+, coenzyme A, and heme B respectively). The structural similarities between them are highlighted, which illustrates the precursor nature of many B vitamins while also showing the functionality of the end product used by essential reactions to support human, animal, or cellular life.

FAD, NAD+, and coenzyme A are all essential for the catabolic release of free energy (dG) to power the activity of the cell and more complex life forms. See the article on Catabolism for more details on how these three essential biochemical reactants help support life.

Tetrahydrofolate is a necessary co-reactant for synthesizing some amino acids, such as glycine. Heme B is the porphyrin derivative macrocycle molecule that holds the iron atom in place in hemoglobin, allowing for the transportation of oxygen through blood.

Deficiencies

Several named vitamin deficiency diseases may result from the lack of sufficient B vitamins. Deficiencies of other B vitamins result in symptoms that are not part of a named deficiency disease.

Side effects

B vitamin toxicity

Because water-soluble B vitamins are eliminated in the urine, taking large doses of most B vitamins usually only produces transient side effects (with the only exception being pyridoxine). General side effects may include restlessness, nausea, and insomnia. These side effects are almost always caused by dietary supplements and not food.

Discovery

Related compounds

Many of the following substances have been referred to as vitamins as they were once believed to be vitamins. They are no longer considered as such, and the numbers that were assigned to them now form the "gaps" in the true series of B-complex vitamins described above (for example, 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: can refer to the distinct chemicals choline, adenine, or carnitine.
  • Choline is synthesized by the human body, but not sufficiently to maintain good health, and is now considered an essential dietary nutrient.
  • Adenine is a nucleobase synthesized by the human body.
  • Carnitine is an essential dietary nutrient for certain worms, but not for humans.
• Vitamin B8: adenosine monophosphate (AMP), also known as adenylic acid. Vitamin B8 may also refer to inositol.
• Vitamin B10: para-aminobenzoic acid (pABA or PABA), a chemical component of the folate molecule produced by plants and bacteria, and found in many foods. It is best known as a UV-blocking sunscreen applied to the skin, and is sometimes taken orally for certain medical conditions.
• Vitamin B11: pteroylheptaglutamic acid (PHGA; chick growth factor). Vitamin Bc-conjugate was also found to be identical to PHGA. Derivative of folate ("pteroylmonoglutamic acid" in this nomenclature).
• Vitamin B13: orotic acid.
• 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, also known as pangamate. Promoted in various forms as a dietary supplement and drug; considered unsafe and subject to seizure by the US Food and Drug Administration.
• Vitamin B16: dimethylglycine (DMG) is synthesized by the human body from choline.
• Vitamin B17: pseudoscientific name for the poisonous compound amygdalin, also known as "laetrile" or by the equally pseudoscientific name "nitrilosides" despite the fact that it is a single compound. Amygdalin can be found in various plants, but is most commonly extracted from apricot pits and other similar fruit kernels. Amygdalin is hydrolyzed by various intestinal enzymes to form, among other things, hydrogen cyanide, which is toxic to human beings when exposed to a high enough dosage. Some proponents claim that amygdalin is effective in cancer treatment and prevention, despite its toxicity and a lack of scientific evidence.
• Vitamin B20: L-carnitine.
• Vitamin Bf: carnitine.
• Vitamin Bm: myo-inositol, also called "mouse antialopaecia factor".
• Vitamin Bp: "antiperosis factor", which prevents perosis, a leg disorder, in chicks; can be replaced by choline and manganese salts.
• Vitamin BT: carnitine.
• Vitamin Bv: a type of B6 other than pyridoxine.
• Vitamin BW: a type of biotin other than d-biotin.
• Vitamin Bx: an alternative name for both pABA (see vitamin B10) and pantothenic acid.

References

References

1. (June 2022). "B Vitamins: Functions and Uses in Medicine". The Permanente Journal.
2. (23 September 2021). "B vitamins". MedlinePlus, National Library of Medicine, US National Institutes of Health.
3. Stipanuk, M.H.. (2006). "Biochemical, physiological, molecular aspects of human nutrition". Saunders Elsevier.
4. (May 2009). "Health effects of vegan diets". The American Journal of Clinical Nutrition.
5. (14 February 2018). "Vitamin B12 supplements are essential for vegans".
6. (September 1988). "Vitamin B-12: plant sources, requirements, and assay". The American Journal of Clinical Nutrition.
7. Woolston, Chris. (14 July 2008). "B vitamins don't boost energy drinks' power". [[Los Angeles Times]].
8. "Vitamin B injections mentioned".
9. (October 2007). "High prevalence of low plasma thiamine concentration in diabetes linked to a marker of vascular disease". Diabetologia.
10. (May 1995). "Periconceptional vitamin use, dietary folate, and the occurrence of neural tube defects". Epidemiology.
11. (2011). "Thiamin (vitamin B1)". [[Journal of Evidence-Based Complementary & Alternative Medicine]].
12. (2 September 2009). "Guide to Nutritional Supplements". Academic Press.
13. (2011). "Understanding Nutrition". Cengage Learning.
14. (1998). "Dietary Reference Intakes for Tjiamine, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin and Choline". National Academy Press.
15. Schnepp, Zoe. (2002). "Pantothenic Acid". University of Bristol.
16. (2009). "Advanced nutrition and human metabolism". Cengage Learning.
17. (May 2014). "Vitamin B₆". Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis, OR.
18. Schnepp, Zoe. (2002). "Biotin". University of Bristol.
19. (1998). "Dietary Reference Intakes for Thiamine, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin and Choline". National Academy Press.
20. Schnepp, Zoe. (2002). "Vitamin B12". University of Bristol.
21. Sardesai, Vishwanath. (11 April 2003). "Introduction to Clinical Nutrition". CRC Press.
22. Food and Nutrition Board, Institute of Medicine. (1998). "Dietary Reference Intakes: Thiamin, Riboflavin, Niacin, Vitamin B6, Vitamin B12, Pantothenic Acid, Biotin, and Choline". National Academy Press.
23. Gyorgy, Paul. (December 1939). "The Curative Factor (vitamin H) for Egg White Injury, with Particular Reference to Its Presence in Different Foodstuffs and in Yeast". Journal of Biological Chemistry.
24. (10 October 1988). "Dean Burk, 84, Chemist for Cancer Institute". The New York Times.
25. "The Nobel Prize and the Discovery of Vitamins".
26. Manjit Rakkar & Keith Hillier. (2007). "Choline". xPharm: The Comprehensive Pharmacology Reference.
27. Navarra, Tova. (1 January 2004). "The Encyclopedia of Vitamins, Minerals, and Supplements". Infobase Publishing.
28. (30 July 2010). "Handbook of Biochemistry and Molecular Biology". CRC Press.
29. (November 2009). "Choline: an essential nutrient for public health". Nutrition Reviews.
30. (1930). "The assay of vitamin B(4)". The Biochemical Journal.
31. (24 August 2007). "Handbook of Nutrition and Food". CRC Press.
32. "Vitamin B8 (Inositol) Overview Information". WebMD, LLC.
33. "Vitamin B10 (Para–aminobenzoic acid (PABA)): uses, side effects, interactions and warnings". WebMD, LLC.
34. (December 2012). "Lactic acid bacteria producing B-group vitamins: a great potential for functional cereals products". Applied Microbiology and Biotechnology.
35. (1947). "A comparative study of the effectiveness of synthetic folic acid, pteroyldiglutamic acid, pteroyltriglutamic acid and pteroylheptaglutamic acid (Bc conjugate).". Internationale Zeitschrift für Vitaminforschung.
36. (15 February 1995). "Total Nutrition: The Only Guide You'll Ever Need - From The Icahn School of Medicine at Mount Sinai". St. Martin's Press.
37. (March 1995). "CPG Sec. 457.100 Pangamic Acid and Pangamic Acid Products Unsafe for Food and Drug Use". US [[Food and Drug Administration]].
38. (February 1984). "The whys of cancer quackery". Cancer.
39. Velisek, Jan. (24 December 2013). "The Chemistry of Food". Wiley.
40. Velisek, Jan. (24 December 2013). "The Chemistry of Food". Wiley.
41. Bender, David A.. (29 January 2009). "A Dictionary of Food and Nutrition". Oxford University Press.
42. Bender, David A.. (11 September 2003). "Nutritional Biochemistry of the Vitamins". Cambridge University Press.
43. (July 1952). "Chemical studies on vitamin BT isolation and characterization as carnitine". Archives of Biochemistry and Biophysics.
44. "Para-aminobenzoic acid". United States [[National Institutes of Health]].