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vitamin B complex

 
Dictionary: vitamin B complex
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n.
A group of water-soluble vitamins including thiamine, riboflavin, niacin, pantothenic acid, biotin, pyridoxine, folic acid, inositol, and vitamin B12 and occurring chiefly in yeast, liver, eggs, and some vegetables. Also called B complex.


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Chemistry Dictionary: vitamin B complex
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A group of water-soluble vitamins that characteristically serve as components of coenzymes. Plants and many microorganisms can manufacture B vitamins but dietary sources are essential for most animals. Heat and light tend to destroy B vitamins.

Vitamin B1 (thiamin(e)) is a precursor of the coenzyme thiamine pyrophosphate, which functions in carbohydrate metabolism. Deficiency leads to beriberi in humans and to polyneuritis in birds. Good sources include brewer's yeast, wheatgerm, beans, peas, and green vegetables.

Vitamin B2 (riboflavin) occurs in green vegetables, yeast, liver, and milk. It is a constituent of the coenzymes FAD and FMN, which have an important role in the metabolism of all major nutrients as well as in the oxidative phosphorylation reactions of the electron transport chain. Deficiency of B2 causes inflammation of the tongue and lips and mouth sores.

Vitamin B6 (pyridoxine) is widely distributed in cereal grains, yeast, liver, milk, etc. It is a constituent of a coenzyme (pyridoxal phosphate) involved in amino acid metabolism. Deficiency causes retarded growth, dermatitis, convulsions, and other symptoms.

Vitamin B12 (cyanocobalamin; cobalamin) is manufactured only by microorganisms and natural sources are entirely of animal origin. Liver is especially rich in it. One form of B12 functions as a coenzyme in a number of reactions, including the oxidation of fatty acids and the synthesis of DNA. It also works in conjunction with folic acid (another B vitamin) in the synthesis of the amino acid methionine and it is required for normal production of red blood cells. Vitamin B12 can only be absorbed from the gut in the presence of a glycoprotein called intrinsic factor; lack of this factor or deficiency of B12 results in pernicious anaemia.

Other vitamins in the B complex include nicotinic acid, pantothenic acid, biotin, and lipoic acid. See also choline.




Vitamin B1



Vitamin B2



Vitamin B6


Food and Nutrition: vitamin B complex
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An old-fashioned term for the various B vitamins: vitamin B1 (thiamin), vitamin B2 (riboflavin), niacin, vitamin B6, vitamin B12, folate, biotin, and pantothenic acid. These vitamins occur together in cereal germ, liver, and yeast; function as coenzymes; and historically were discovered by separation from what was known originally as vitamin B; hence, they are grouped together as the B complex.

Alternative Medicine Encyclopedia: Vitamin B Complex
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Description

The vitamin B complex consists of 12 related water-soluble substances. Eight are considered essential vitamins because they need to be included in the diet. Four are not essential because the body can synthesize them. Although these vitamins are chemically distinct, they are grouped together because they are found with one another in the same foods. Since they are water-soluble, most are not stored for any length of time, and must be replenished daily. The eight vitamins have both names and corresponding numbers. They are:

Biotin is not always included among B complex supplements. The numbers that appear to have been skipped were found to be duplicate substances or non-vitamins. The four unnumbered components of the B complex that can be synthesized by the body are choline, inositol, PABA, and lipoic acid.

As a group, the B vitamins have a broad range of functions, including the maintenance of myelin, which is the covering of nerve cells. A breakdown of myelin can cause a large and devastating variety of neurologic symptoms. B vitamins are also key to producing energy from nutrients that are consumed. Three members of this group—folic acid, pyridoxine, and cobalamin—work together to keep homocysteine levels low. This is quite important, since high homocysteine levels are associated with heart disease. Some B vitamins prevent certain birth defects (including cleft palate and neural tube defects), maintain healthy red blood cells, support immune function, regulate cell growth, aid in hormone production, and may have a role in preventing certain types of cancer. They also help maintain healthy skin, hair, and nails.

General Use

There are many claims regarding the usefulness of various B vitamins. Thiamine is thought to be supportive for people with Alzheimer's disease, a disorder that is also associated with low levels of pyridoxine and cobalamin. High doses of niacin lower cholesterol, and balance high-density (HDL) and low-density (LDL) lipoproteins. This should be done under medical supervision only. Some evidence shows that niacin may prevent juvenile diabetes (type 1, insulin dependent) in at-risk children. It may maintain pancreatic excretion of some insulin for a longer time than would occur normally. Niacin has also been used to relieve intermittent claudication and osteoarthritis, although the dose for the latter may lead to liver problems. The frequency of migraines may be significantly reduced, and the severity decreased, by the use of supplemental riboflavin. Pyridoxine is used therapeutically to lower the risk of heart disease, to relieve nausea associated with morning sickness, and to treat premenstrual syndrome (PMS). In conjunction with magnesium, pyridoxine may have some beneficial effects on the behavior of children with autism. Cobalamin supplementation has been shown to improve male fertility. Depression, dementia, and mental impairment are often associated with deficiencies of both cobalamin and folic acid. Folic acid may reduce the odds of cervical or colon cancer in certain risk groups.

Deficiency

Vitamin B complex is most often used to treat deficiencies that are caused by poor vitamin intake, difficulties with vitamin absorption, or conditions causing increased metabolism, such as hyperthyroidism, which deplete vitamin levels at a higher than normal rate.

Biotin and pantothenic acid are rarely deficient since they are broadly available in foods, but often persons lacking one type of B vitamin are lacking other B components as well. An individual who may have symptoms due to an inadequate level of one vitamin may suffer from an undetected underlying deficiency as well. One possibility of particular concern is that taking folic acid supplements can cover up the symptoms of cobalamin deficiency. This scenario could result in permanent neurologic damage if the cobalamin shortage remains untreated.

Some of the B vitamins have unique functions within the body that allow a particular deficiency to be readily identified. Often, however, they work in concert so symptoms due to various inadequate components may overlap. In general, poor B vitamin levels will cause profound fatigue and an assortment of neurologic manifestations, which may include weakness, poor balance, confusion, irritability, memory loss, nervousness, tingling of the limbs, and loss of coordination. Depression may be an early sign of significantly low levels of pyridoxine, as well as other B vitamins. Additional symptoms of vitamin B deficiency are sleep disturbances, nausea, poor appetite, frequent infections, and skin lesions.

A certain type of anemia (megaloblastic) is an effect of inadequate cobalamin. This anemia can also occur if a person stops secreting enough intrinsic factor in the stomach. Intrinsic factor is essential for the absorption of cobalamin. A lack of intrinsic factor also leads to pernicious anemia, so called because it persists despite iron supplementation. Neurologic symptoms often precede anemia when cobalamin is deficient.

A severe and prolonged lack of niacin causes a condition called pellagra. The classic signs of pellagra are dermatitis, dementia, and diarrhea. It is very rare now, except in alcoholics, strict vegans, and people in areas of the world with very poor nutrition.

Thiamine deficiency is similarly rare, except among the severely malnourished and alcoholics. A significant depletion causes a condition known as beriberi, which can cause weakness, leg spasms, poor appetite, and loss of coordination. Wernicke-Korsakoff syndrome is the most severe form of deficiency, and occurs in conjunction with alcoholism. Early stages of neurologic symptoms are reversible, but psychosis and death may occur if the course is not reversed.

Risk Factors for Deficiency

People are at higher risk for deficiency if they have poor nutritional sources of B vitamins, take medications, or have conditions that impair absorption, or are affected by circumstances causing them to require above-normal levels of vitamin B components. Since the B vitamins often work in harmony, a deficiency in one type may have broad implications. Poor intake of B vitamins is most often a problem in strict vegetarians and the elderly. People who frequently fast or diet may also benefit from B vitamin supplements. Vegans need to use brewer's yeast or other sources of supplemental cobalamin, since the only natural sources are meats.

Risk factors that may decrease absorption of some B vitamins include smoking; excessive use of alcohol; surgical removal of portions of the digestive tract; and advanced age. Absorption is also impaired by some medications. Some of the drugs that may cause decreased absorption are corticosteroids, colchicine, metformin, phenformin, omeprazol, colestipol, cholestyramine, methotrexate, 5-fluorouracil, tricyclic antidepressants, and slow-release potassium.

A person's requirement for vitamin B complex may be increased by such conditions as pregnancy, breast-feeding, emotional stress, and physical stress due to surgery or injury. People who are very physically active require extra riboflavin. Use of birth control pills also increases the need for certain B vitamins.

Recent research indicates that children with sickle cell anemia are at high risk for elevated homocysteine levels and pyridoxine deficiency.

Studies of folic acid deficiency caused by cancer chemotherapy indicate that some patients are at greater risk than others due to genetic variations in metabolism of the B vitamins. Further research is needed to determine the role of these genetic factors in vitamin deficiency states.

Preparations

Natural Sources

Although they are prevalent in many foods, fresh meats and dairy products are the best sources for most of the B vitamins. Cobalamin is only found naturally in animal source foods. Freezing of food and exposing foods or supplements to light may destroy some of the vitamin content. Dark-green leafy vegetables are an excellent source of folic acid. To make the most of the B vitamins contained in foods, they should not be overcooked. It is best to steam vegetables, rather than boil or simmer them.

Supplemental Sources

B vitamins are generally best taken in balanced complement, unless there is a specific deficiency or need for an individual vitamin. An excess of one component may lead to depletion of the others. Injectable and oral forms of supplements are available. The injectable types may be more useful for those with deficiencies due to problems with absorption. B complex products vary in terms of components and dose level contained within them.

Individual components are also available as supplements. These are best used with the advice of a health care professional. Some are valuable when addressing specific problems such as pernicious anemia. Strict vegetarians will need to incorporate a supplemental source of B12 in their diets.

Precautions

In many cases, large doses of water-soluble vitamins can be taken with no ill effects since excessive amounts are readily excreted. However, liver inflammation may occur when niacin is taken at daily doses of over 500 mg. This problem occurs more often at doses six times as high. It is generally reversible once the supplementation is stopped. Niacin may also cause difficulty in controlling blood sugar in diabetics. It can increase uric acid levels, which will aggravate gout. Those with ulcers could be adversely affected, as niacin increases the production of stomach acid. Niacin also lowers blood pressure due to its vasodilatory effect, so it should not be taken in conjunction with medications that treat high blood pressure. If a form of niacin known as inositol hexaniacinate is taken, the beneficial effects on cholesterol are maintained without incurring the problems of flushing, gout, and ulcers.

High doses of pyridoxine may cause liver inflammation or permanent nerve damage. Megadoses of this vitamin are not necessary or advisable.

Thoseon medications for seizures, high blood pressure, and Parkinson's disease are at increased risk for interactions. Persons who have chronic health conditions, or take other medications, should seek the advice of a health professional before beginning any program of supplementation.

Side Effects

In large amounts, niacin commonly causes flushing and headache, although this can be avoided by taking it in the form of inositol hexaniacinate. Large doses of riboflavin result in very bright yellow urine.

Interactions

Some medications may be affected by B vitamin supplementation, including those prescribed for high blood pressure; Parkinson's disease (such as levodopa, which is inactivated by pantothenic acid); and epileptiform conditions. Folic acid interacts with Dilantin (a brand name for phenytoin sodium), as well as other anticonvulsants. Large amounts of vitamin C taken within an hour of vitamin B supplements will destroy the cobalamin component. Niacin may interfere with control of blood sugar in people on antidiabetic drugs. Isoniazid, a medication to treat tuberculosis, can impair the proper production and utilization of niacin. Antibiotics potentially decrease the level of some B vitamins by killing the digestive tract bacteria that produce them.

Resources

Books

Bratman, Steven, and David Kroll. Natural Health Bible. CA Prima Publishing, 1999.

Feinstein, Alice. Prevention's Healing with Vitamins. PA: Rodale Press, 1996.

Griffith, H. Winter. Vitamins, Herbs, Minerals & Supplements: The Complete Guide. AZ: Fisher Books, 1998.

Janson, Michael. The Vitamin Revolution in Health Care. Arcadia Press, 1996.

Jellin, Jeff, Forrest Batz, and Kathy Hitchens. Pharmacist's letter/Prescriber's Letter Natural Medicines Comprehensive Database. CA: Therapeutic Research Faculty, 1999.

Pressman, Alan H., and Sheila Buff. The Complete Idiot's Guide to Vitamins and Minerals. New York: Alpha Books, 1997.

Periodicals

Wolters M., A. Strohle, and A. Hahn. "Age-associated changes in the metabolism of vitamin B12 and folic acid: Prevalence, aetiopathogenesis and pathophysiological consequences." Z Gerontol Geriatr. 2004 Apr;37(2):109-35. (article in German, reviewed in abstract only

Balasa, W., K. A. Kalinyak, J. A. Bean, et al. "Hyperhomocysteinemia is Associated with Low Plasma Pyridoxine Levels in Children with Sickle Cell Disease." Journal of Pediatric Hematology and Oncology 24 (June-July 2002): 374-9.

Fairfield, K. M., and R. H. Fletcher. "Vitamins for ChronicDisease Prevention in Adults: Scientific Review." Journal of the American Medical Association (JAMA) 287 (June 19, 2002): 3116-26.

McCaddon, A., B. Regland, P. Hudson, and G. Davies. "Functional Vitamin B12 Deficiency and Alzheimer's Disease." Neurology 58 (May 14, 2002): 1395-9.

Miller, J. W., R. Green, D. M. Mungas, et al. "Homocysteine, Vitamin B6, and Vascular Disease in AD Patients." Neurology 58 (May 28, 2002): 1449-50.

Morris, M. S. "Folate, Homocysteine, and Neurological Function." Nutrition in Clinical Care 5 (May-June 2002): 124-32.

Prescott, N. J., and S. Malcolm. "Folate and the Face: Evaluating the Evidence for the Influence of Folate Genes on Craniofacial Development." The Cleft Palate-Craniofacial Journal 39 (May 2002): 327-31.

Ulrich, C. M., K. Robien, and R. Sparks. "Pharmacogenetics and Folate Metabolis—A Promising Direction." Pharmacogenomics 3 (May 2002): 299-313.

Organizations

American Dietetic Association. 216 West Jackson Blvd., Chicago, IL 60606. (312) 899-0040. .

[Article by: Rebecca J. Frey, Ph.D.; Samuel Uretsky, Pharm.D.]

Britannica Concise Encyclopedia: vitamin B complex
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Water-soluble organic compounds with loosely similar properties, distribution in natural sources, and physiological functions. Most are coenzymes, and all appear essential to the metabolic processes of all animal life. They include thiamin (B1), riboflavin (B2), niacin, vitamin B6, pantothenic acid, folic acid, biotin, and vitamin B12 (cobalamin); some authorities also include choline, carnitine, lipoic acid, inositol, and para-aminobenzoic acid. Vitamin B6 is needed for metabolism of amino acids and prevention of skin and nerve disorders. Vitamin B12 prevents pernicious anemia and is involved in nucleic-acid synthesis, fat metabolism, and conversion of carbohydrate to fat. The B complex vitamins are particularly abundant in cereal grains, meats, nuts, and some fruits and vegetables.

For more information on vitamin B complex, visit Britannica.com.

Wikipedia: B vitamins
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B vitamin supplement tablets

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.).

Contents

List of B vitamins

Health benefits

The B vitamins are necessary in order to:

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.[4]

B vitamin deficiency

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.

Vitamin Name Deficiency effects
Vitamin B1 thiamine 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.
Vitamin B2 riboflavin 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.
Vitamin B3 niacin 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.
Vitamin B5 pantothenic acid Deficiency can result in acne and paresthesia, although it is uncommon.
Vitamin B6 pyridoxine Deficiency may lead to anemia, depression, dermatitis, high blood pressure (hypertension), water retention, and elevated levels of homocysteine.
Vitamin B7 biotin Deficiency does not typically cause symptoms in adults but may lead to impaired growth and neurological disorders in infants.
Vitamin B9 folic acid 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.
Vitamin B12 cobalamin 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 vitamin toxicity

Although most B vitamins are eliminated regularly in the urine, taking large doses of certain B vitamins may produce harmful effects.

Vitamin Name Tolerable Upper Intake Level Harmful effects
Vitamin B1 thiamine None No known toxicity from oral intake. There are some reports of anaphylaxis caused by high dose thiamin injections into the vein or muscle. However, the doses were greater than the quantity humans can physically absorb from oral intake.[5]
Vitamin B2 riboflavin None No known toxicity
Vitamin B3 niacin 35 mg/day from supplements, drugs or fortified food Flushing (redness of the skin, often accompanied by itching or a mild burning sensation). Intake of 3000 mg/day of nicotinamide and 1500 mg/day of nicotinic acid are associated with nausea, vomiting, and signs and symptoms of liver toxicity.[6]
Vitamin B5 pantothenic acid None No known toxicity
Vitamin B6 pyridoxine 100 mg/day from supplements, drugs or fortified food sensory neuropathy and dermatological lesions[7]
Vitamin B7 biotin None No known toxicity
Vitamin B9 folic acid 1 mg/day Masks B12 deficiency, which can lead to permanent neurological damage[8]
Vitamin B12 cyanocobalamin None No known toxicity

B vitamin sources

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 oil, 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". As might be expected, due to its high content of brewer's yeast, beer is a source of B vitamins[9], although this may be less true for filtered beers[10] and the alcohol in beer may impair the body's ability to absorb certain vitamins.[11]

The B-12 vitamin is of note because it is not available from plant products, making B-12 deficiency a concern for vegans. Manufacturers of plant-based foods will sometimes report B-12 content, leading to confusion about what sources yield B-12. The confusion arises because the standard US Pharmacopeia (USP) method for measuring the B-12 content does not measure the B-12 directly. Instead, it measures a bacterial response to the food. Chemical variants of the B-12 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 B-12 content in other types of foods as well.[12]

Vitamin B may also be delivered by injection to reverse deficiencies.[13]

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 8,333% of the recommended dietary allowance of vitamin B-12 and 2,000% of the RDA for vitamin B-6. Red Bull offers 360% of the RDA for vitamin B-6, 120% of B12, 140% of niacin (vitamin B3)"[14]) with claims that this will cause the consumer to "sail through your day without feeling jittery or tense." [14] Nutritionists, such as Professor Hope Barkoukis, dismiss these claims: "It's brilliant marketing, but it doesn't have any basis [in fact]."[14]

While B vitamins do "help unlock the energy in foods... Just about everyone in 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…"[14] The elderly and athletes may need to supplement their intake of B-12 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.[15] 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."[14]

Related nutrients

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.[16]
  • 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.[citation needed]
  • Vitamin B8: adenosine monophosphate, or alternately myo-inositol, is synthesized by the human body.[citation needed]
  • 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.[citation needed]
  • 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.[17]
  • 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-δ.
  • Vitamin Bh: biotin
  • Vitamin Bm: "mouse factor": also used to designate inositol
  • Vitamin Bp: choline[dubious – discuss] Choline is only required for survival of some mutants. Most commonly it is synthesized in vivo de novo [18] May be added as supplement especially when methionine supply is limited.
  • Vitamin Bt: L-carnitine
  • Vitamin Bv: a type of B6 but not pyridoxine[clarification needed]
  • Vitamin Bw: a type of biotin but not d-biotin[clarification needed]
  • 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.

References

  1. ^ "Confronting Pancreatic Cancer". http://www.pancreatica.org. Retrieved 2008-02-08. 
  2. ^ Schernhammer, E., et al. (June 1, 2007). "Plasma Folate, Vitamin B6, Vitamin B12, and Homocysteine and Pancreatic Cancer Risk in Four Large Cohorts". Cancer Research 67 (11): 5553–60. doi:10.1158/0008-5472.CAN-06-4463. http://cancerres.aacrjournals.org/cgi/content/abstract/67/11/5553. Retrieved 2008-02-08. 
  3. ^ United Press International (June 1, 2007). "Pancreatic cancer risk cut by B6, B12". UPI.com. http://www.upi.com/Consumer_Health_Daily/Briefing/2007/06/01/pancreatic_cancer_risk_cut_by_b6_b12/3712/. Retrieved 2008-02-08. 
  4. ^ Vitamins, water soluble at FAQ.org
  5. ^ National Academy of Sciences. Institute of Medicine. Food and Nutrition Board., ed (1998). "Chapter 4 - Thiamin". Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, D.C.: National Academy Press. pp. 58–86. ISBN 0-309-06411-2. http://www.nal.usda.gov/fnic/DRI//DRI_Thiamin/58-86_150.pdf. Retrieved 2009-06-17. 
  6. ^ National Academy of Sciences. Institute of Medicine. Food and Nutrition Board., ed (1998). "Chapter 6 - Niacin". Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, D.C.: National Academy Press. pp. 150–195. ISBN 0-309-06411-2. http://www.nal.usda.gov/fnic/DRI//DRI_Thiamin/123-149_150.pdf. Retrieved 2009-06-17. 
  7. ^ National Academy of Sciences. Institute of Medicine. Food and Nutrition Board., ed (1998). "Chapter 7 - Vitamin B6". Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, D.C.: National Academy Press. pp. 150–195. ISBN 0-309-06411-2. http://www.nal.usda.gov/fnic/DRI//DRI_Thiamin/150-195_150.pdf. Retrieved 2009-06-17. 
  8. ^ National Academy of Sciences. Institute of Medicine. Food and Nutrition Board., ed (1998). "Chapter 8 - Folate". Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, D.C.: National Academy Press. pp. 58–86. ISBN 0-309-06411-2. http://www.nal.usda.gov/fnic/DRI//DRI_Thiamin/196-305_150.pdf. Retrieved 2009-06-17. 
  9. ^ Glaser, Gregg (July 2002). "Beer and Your Health". All About Beer Magazine. http://www.allaboutbeer.com/features/233beer&health.html. Retrieved 2007-01-05. 
  10. ^ Harden, A and Zylva, S S (1924-07-21) (PDF). Investigation of Barley, Malt and Beer for Vitamins B and C. Lister Institute. http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1259493&blobtype=pdf. Retrieved 2007-01-05. 
  11. ^ Watson, Ronald; Watzl, Bernhard, eds (September 1992). Nutrition and alcohol. CRC Press. pp. 16–18. ISBN 978-0849379338. 
  12. ^ Herbert, Victor (01 Sep 1998). "Vitamin B-12: Plant sources, requirements, and assay". Am. J. Clin. Nutr. 48 (3): 852–8. http://www.ajcn.org/cgi/reprint/48/3/852. Retrieved 2008-02-26. 
  13. ^ Vitamin B injections mentioned
  14. ^ a b c d e Chris Woolston (July 14, 2008). "B vitamins don't boost energy drinks' power". Los Angeles Times. http://www.latimes.com/features/health/la-he-skeptic14-2008jul14,0,3939169.story. Retrieved 2008-10-08. 
  15. ^ http://www.ncbi.nlm.nih.gov/pubmed/7619926
  16. ^ Vera Reader (1930). "The assay of vitamin B4". Biochem J. 24 (6): 1827–31.. doi:10.1007/BF01581575. http://www.biochemj.org/bj/024/1827/0241827.pdf. 
  17. ^ Clark, Jim (September 2003). "Foods Containing B17". All Natural Cancer Therapy. http://web.archive.org/web/20070828221422/http://home.bluegrass.net/~jclark/b17_dosage.htm. Retrieved 2007-07-07. 
  18. ^ american journal of clinical nutrition; J A Stecol; ... pdf
v • d • e
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v • d • e
Nutrition disorders (E40-68, 260-269)
Hypoalimentation/
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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
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Food and Nutrition. A Dictionary of Food and Nutrition. Copyright © 1995, 2003, 2005 by A. E. Bender and D. A. Bender. All rights reserved.  Read more
Alternative Medicine Encyclopedia. Encyclopedia of Alternative Medicine. Copyright © 2005 by The Gale Group, Inc. All rights reserved.  Read more
Britannica Concise Encyclopedia. Britannica Concise Encyclopedia. © 2006 Encyclopædia Britannica, Inc. All rights reserved.  Read more
Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "B vitamins".  Read more