The B vitamins are eight water-soluble vitamins that play important roles in cell metabolism. Historically, the B vitamins were once thought to be a single vitamin, referred to as vitamin B (much as people refer to vitamin C or vitamin D). Later research showed that they are chemically distinct vitamins that often coexist in the same foods. Supplements containing all eight are generally referred to as a vitamin B complex. Individual B vitamin supplements are referred to by the specific name of each vitamin (e.g. B1, B2, B3 etc.).
The B vitamins are necessary in order to:
- Support and increase the rate of metabolism
- Maintain healthy skin and muscle tone
- Enhance immune and nervous system function
- Promote cell growth and division—including that of the red blood cells that help prevent anemia.
- Reduce the risk of pancreatic cancer, one of the most lethal forms of cancer, when consumed in food, but not when ingested in vitamin tablet form.
All B vitamins are water soluble, and are dispersed throughout the body. Most of the B vitamins must be replenished regularly, since any excess is excreted in the urine.
The main eight B vitamins are:
||Deficiency causes beriberi. Symptoms of this disease of the nervous system include weight loss, emotional disturbances, Wernicke's encephalopathy (impaired sensory perception), weakness and pain in the limbs, periods of irregular heartbeat, and edema (swelling of bodily tissues). Heart failure and death may occur in advanced cases. Chronic thiamine deficiency can also cause Korsakoff's syndrome, an irreversible psychosis characterized by amnesia and confabulation.
||Deficiency causes ariboflavinosis. Symptoms may include cheilosis (cracks in the lips), high sensitivity to sunlight, angular cheilitis, glossitis (inflammation of the tongue), seborrheic dermatitis or pseudo-syphilis (particularly affecting the scrotum or labia majora and the mouth), pharyngitis, hyperemia, and edema of the pharyngeal and oral mucosa.
||Deficiency, along with a deficiency of tryptophan causes pellagra. Symptoms include aggression, dermatitis, insomnia, weakness, mental confusion, and diarrhea. In advanced cases, pellagra may lead to dementia and death.
||Deficiency can result in acne and paresthesia, although it is uncommon.
||Deficiency may lead to microcytic anemia (because pyridoxyl phosphate is the cofactor for heme synthesis), depression, dermatitis, high blood pressure (hypertension), water retention, and elevated levels of homocysteine.
||Deficiency does not typically cause symptoms in adults but may lead to impaired growth and neurological disorders in infants. Multiple carboxylase deficiency, an inborn error of metabolism, can lead to biotin deficiency even when dietary biotin intake is normal.
||Deficiency results in a macrocytic anemia, and elevated levels of homocysteine. Deficiency in pregnant women can lead to birth defects. Supplementation is often recommended during pregnancy. Researchers have shown that folic acid might also slow the insidious effects of age on the brain.
||Deficiency results in a macrocytic anemia, elevated homocysteine, peripheral neuropathy, memory loss and other cognitive deficits. It is most likely to occur among elderly people as absorption through the gut declines with age; the autoimmune disease pernicious anemia is another common cause. It can also cause symptoms of mania and psychosis. In rare extreme cases, paralysis can result.
B vitamins are found in all whole, unprocessed foods. Processing, as with sugar and white flour, tends to significantly reduce B vitamin content. B vitamins are particularly concentrated in meat and meat products such as liver, turkey, and tuna. Other good sources for B vitamins are potatoes, bananas, lentils, chile peppers, tempeh, beans, nutritional yeast, brewer's yeast, and molasses. Marmite and Vegemite bill themselves as "one of the world's richest known sources of vitamin B". Although the yeast used to make beer results in beer being a source of B vitamins, their bioavailability ranges from poor to negative given the fact consumption of ethanol is known to inhibit absorption of thiamine (B1), riboflavin (B2), niacin (B3), biotin (B7),and folic acid (B9). Additionally, each of the preceding studies further emphasizes that elevated consumption of beer and other ethanol-based drinks results in a net deficit of those B vitamins and the health risks associated with such deficiencies.
The B12 vitamin is of note because it is not available from plant products, making B12 deficiency a concern for vegans. 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. Vitamin B may also be delivered by injection to reverse deficiencies.
Another popular means of increasing one's vitamin B intake is through the use of dietary supplements purchased at supermarkets, health centers, or natural food stores. B vitamins are also commonly added to energy drinks. Many energy drinks have been marketed with large amounts of B vitamins (5-Hour Energy contains an astounding 8333% of the recommended dietary allowance of vitamin B12 and 2000% of the RDA for vitamin B6. Red Bull offers "360% of the RDA for vitamin B6, 120% of B12, 140% of niacin (vitamin B3)" with claims that this will cause the consumer to "sail through your day without feeling jittery or tense."Nutritionists, such as Case Western University Professor Hope Barkoukis, dismiss these claims: "It's brilliant marketing, but it doesn't have any basis [in fact]."
While B vitamins do "help unlock the energy in foods... Just about everyone in Europe and America already gets all of the B vitamins they could possibly need in their diets… Extra B vitamins are generally just flushed out of the system—although everyone's limit of absorption is different in regards to B complex vitamins and no-one knows how much is needed on an individual basis of these vitamins. 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. Also, Vitamin B9 (folic acid) 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 folic acid intake and/or take a supplement. However, for "most typical consumers of energy supplements or drinks, B vitamins are nothing more than a 'gimmick' when they are making these false claims."
Many of the following substances have been referred to as vitamins because they were believed to be vitamins at one time, and they are relevant to vitamin nomenclature in that the numbers that were assigned to them form "gaps" in the series of B-vitamin names. Some of them, though not essential to humans, are essential in the diets of other organisms; others have no known nutritional value.
- Vitamin B4: adenine, a nucleobase, is synthesized by the human body.
- Vitamin B7: "vitamin I" of Centanni E. (1935)—also called "Enteral factor"—is a water and alcohol soluble rice-bran factor which prevents digestive disturbance in pigeons. It governs the anatomical and functional integrity of the intestinal tract. Later found in yeast. Possible candidates for this substance are inositol, niacin (nicotinic acid), and biotin. Carnitine was also claimed to be a candidate but is not soluble in alcohol.
- Vitamin B8: adenosine monophosphate, or alternately myo-inositol, is synthesized by the human body.
- Vitamin B10: para-aminobenzoic acid (PABA)
- Vitamin B11: pteryl-hepta-glutamic acid—chick growth factor, which is a form of folic acid. Later found to be one of five folates necessary for humans; also known as vitamin S or factor S. L-Carnitine is called vitamin B11 in France.
- Vitamin B13: orotic acid, now known to not be a vitamin.
- Vitamin B14: cell proliferant, anti-anemia, rat growth, 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
- Vitamin B16: dimethylglycine (DMG)
- Vitamin B17: amygdalin, nitrilosides, or laetrile. These substances are found in a number of seeds, sprouts, beans, tubers and grains. While toxic in large quantities, proponents claim that it is effective in cancer treatment and prevention.
- Vitamin B18:
- Vitamin B19:
- Vitamin B20: carnitine
- Vitamin B21:
- Vitamin B22: often claimed as an ingredient of Aloe vera extracts but also in many other foods. Claimed by one source to be vitamin B12b-d.
- Vitamin Bh: biotin
- Vitamin Bm: "mouse factor": also used to designate inositol
- Vitamin Bp: choline Choline is only required for survival of some mutants. Most commonly it is synthesized in vivo de novo. May be added as supplement especially when methionine supply is limited.
- Vitamin Bt: L-carnitine
- Vitamin Bv: a type of B6 but not pyridoxine
- Vitamin Bw: a type of biotin but not d-biotin
- Vitamin Bx: para-aminobenzoic acid
Note: B16, B17, B18, B19, B20, B21 & B22 do not appear to be animal factors but are claimed by some naturopaths as human therapeutic factors.
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