B vitamins

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B vitamins are a class of water-soluble vitamins that play important roles in cell metabolism and synthesis of red blood cells. [1] They are a chemically diverse class of compounds; some contain sulfur and B12 contains cobalt. [1] Dietary supplements containing all eight are referred to as a vitamin B complex. Individual B vitamins are referred to by B-number or by chemical name, such as B1 for thiamine, B2 for riboflavin, and B3 for niacin, [1] while some are more commonly recognized by name than by number, such as pantothenic acid (B5), biotin (B7), and folate (B9).

Contents

Each B vitamin is either a cofactor (generally a coenzyme) for key metabolic processes or is a precursor needed to make one. [1]

List of B vitamins

List of B vitamins
VitaminNameDescription
Vitamin B1 Thiamine A coenzyme in the catabolism of sugars and amino acids.
Vitamin B2 Riboflavin A precursor of coenzymes called FAD and FMN, which are needed for flavoprotein enzyme reactions, including activation of other vitamins
Vitamin B3 Niacin (nicotinic acid)A precursor of coenzymes called NAD and NADP, which are needed in many metabolic processes.
Niacinamide
Nicotinamide riboside
Vitamin B5 Pantothenic acid A precursor of coenzyme A and therefore needed to metabolize many molecules.
Vitamin B6 Pyridoxine A coenzyme in many enzymatic reactions in metabolism.
Pyridoxal
Pyridoxamine
Vitamin B7 Biotin A coenzyme for carboxylase enzymes, needed for synthesis of fatty acids and in gluconeogenesis.
Vitamin B9 Folate A precursor needed to make, repair, and methylate DNA; a cofactor in various reactions; especially important in aiding rapid cell division and growth, such as in infancy and pregnancy.
Vitamin B12 Cobalamins Commonly cyanocobalamin or methylcobalamin in vitamin supplements. A coenzyme involved in the metabolism of all animal cells, especially affecting DNA synthesis and regulation, but also fatty acid metabolism and amino acid metabolism.

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 #Related compounds for numbers 4, 8, 10, 11, and others.

Sources

B vitamins are found in abundance in meat, eggs, and dairy products. [1] Processed carbohydrates such as sugar and white flour tend to have lower B vitamin content than their unprocessed counterparts. For this reason, it is common in many countries (including the United States) that the B vitamins thiamine, riboflavin, niacin, and folic acid are added back to white flour after processing. This is referred to as "enriched flour" on food labels. B vitamins are particularly concentrated in meat such as turkey, tuna and liver. [2]

Sources for B vitamins also include spinach, legumes (pulses or beans), whole grains, asparagus, potatoes, bananas, chili peppers, breakfast cereals. [1] The B12 vitamin is not abundantly available from plant products [3] (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), [4] 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. [5]

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. [6]

Because they are soluble in water, excess B vitamins are generally readily excreted, although individual absorption, use and metabolism may vary. [6] 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.[ medical citation needed ] In cases of severe deficiency, B vitamins, especially B12, may also be delivered by injection to reverse deficiencies. [7] [ unreliable medical source? ] 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. [8] 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. [9]

Molecular functions

VitaminNameStructureMolecular function
Vitamin B1 Thiamine
Thiamin.svg
Thiamine plays a central role in the release of energy from carbohydrates. It is involved in RNA and DNA production, as well as nerve function. Its active form is a coenzyme called thiamine pyrophosphate (TPP), which takes part in the conversion of pyruvate to acetyl coenzyme A in metabolism. [10]
Vitamin B2 Riboflavin
Riboflavin.svg
Riboflavin is involved in release of energy in the electron transport chain, the citric acid cycle, as well as the catabolism of fatty acids (beta oxidation). [11]
Vitamin B3 Niacin
Niacin structure.svg
Niacin is composed of two structures: nicotinic acid and nicotinamide. There are two co-enzyme forms of niacin: nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). Both play an important role in energy transfer reactions in the metabolism of glucose, fat and alcohol. [12] NAD carries hydrogens and their electrons during metabolic reactions, including the pathway from the citric acid cycle to the electron transport chain. NADP is a coenzyme in lipid and nucleic acid synthesis. [13]
Vitamin B5 Pantothenic acid
(R)-Pantothenic acid Formula V.1.svg
Pantothenic acid is involved in the oxidation of fatty acids and carbohydrates. Coenzyme A, which can be synthesised from pantothenic acid, is involved in the synthesis of amino acids, fatty acids, ketone bodies, cholesterol, [14] [ better source needed ] phospholipids, steroid hormones, neurotransmitters (such as acetylcholine), and antibodies. [15]
Vitamin B6 Pyridoxine, pyridoxal, pyridoxamine
Pyridoxal-phosphate.svg
The active form pyridoxal 5'-phosphate (PLP) (depicted) serves as a cofactor in many enzyme reactions mainly in amino acid metabolism including biosynthesis of neurotransmitters. [16]
Vitamin B7 Biotin
Biotin structure JA.png
Biotin plays a key role in the metabolism of lipids, proteins and carbohydrates. It is a critical co-enzyme of four carboxylases: acetyl CoA carboxylase, which is involved in the synthesis of fatty acids from acetate; pyruvate CoA carboxylase, involved in gluconeogenesis; β-methylcrotonyl CoA carboxylase, involved in the metabolism of leucine; and propionyl CoA carboxylase, which is involved in the metabolism of energy, amino acids and cholesterol. [17] [ better source needed ]
Vitamin B9 Folate
Folic acid.svg
Folate acts as a co-enzyme in the form of tetrahydrofolate (THF), which is involved in the transfer of single-carbon units in the metabolism of nucleic acids and amino acids. THF is involved in purine and pyrimidine nucleotide synthesis, so is needed for normal cell division, especially during pregnancy and infancy, which are times of rapid growth. Folate also aids in erythropoiesis, the production of red blood cells. [18]
Vitamin B12 Cobalamin
Cobalamin skeletal.svg
Vitamin B12 is involved in the cellular metabolism of carbohydrates, proteins and lipids. It is essential in the production of blood cells in bone marrow, and for nerve sheaths and proteins. [19] [ better source needed ] Vitamin B12 functions as a co-enzyme in intermediary metabolism for the methionine synthase reaction with methylcobalamin, and the methylmalonyl CoA mutase reaction with adenosylcobalamin. [20]
A diagram of the chemical structure of 5 classes of vitamin B (B2, B3, B5, B9, and B12) and the essential biochemical reactants that they are precursors to. Vitamin B precursors.png
A diagram of the chemical structure of 5 classes of vitamin B (B2, B3, B5, B9, and B12) and the essential biochemical reactants that they are precursors to.

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. [1] Deficiencies of other B vitamins result in symptoms that are not part of a named deficiency disease.

VitaminNameDeficiency effects
Vitamin B1 Thiamine Thiamine deficiency causes beriberi. Symptoms of this disease of the nervous system include weight loss, emotional disturbances, Wernicke 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 alcoholic Korsakoff syndrome, an irreversible dementia characterized by amnesia and compensatory confabulation.
Vitamin B2 Riboflavin Riboflavin deficiency can cause ariboflavinosis, which may result in 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 (sore throat), hyperemia, and edema of the pharyngeal and oral mucosa.
Vitamin B3 Niacin 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 (the 3(+1) D's: dermatitis, diarrhea, dementia, and death).
Vitamin B5 Pantothenic acid Pantothenic acid deficiency can result in acne and paresthesia, although it is uncommon.
Vitamin B6 Pyridoxine, pyridoxal, pyridoxamine Vitamin B6 deficiency causes seborrhoeic dermatitis-like eruptions, pink eye and neurological symptoms (e.g. epilepsy).
Vitamin B7 Biotin Biotin deficiency does not typically cause symptoms in adults, other than cosmetic issues such as decreased hair and nail growth, 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.
Folate Folic acid Folic acid deficiency results in a macrocytic anemia, and elevated levels of homocysteine. Deficiency in pregnant women can lead to birth defects, particularly neural tube defects such as spina bifida and anencephaly.
Vitamin B12 Cobalamins Vitamin B12 deficiency results in a macrocytic anemia, elevated methylmalonic acid and homocysteine, peripheral neuropathy, sense loss, change in mobility, 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. Untreated, it is possible to cause irreversible damage to the brain and nerve system — In rare extreme cases, paralysis can result.

Side effects

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

VitaminTolerable Upper Intake Level (UL)Harmful effects
Vitamin B1None [21] 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. [21]
Vitamin B2None [22] No evidence of toxicity based on limited human and animal studies. The only evidence of adverse effects associated with riboflavin comes from in vitro studies showing the production of reactive oxygen species (free radicals) when riboflavin was exposed to intense visible and UV light. [22]
Vitamin B3US UL = 35 mg as a dietary supplement [23] 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. Other effects may include glucose intolerance, and (reversible) ocular effects. Additionally, the nicotinic acid form may cause vasodilatory effects, also known as flushing, including redness of the skin, often accompanied by an itching, tingling, or mild burning sensation, which is also often accompanied by pruritus, headaches, and increased intracranial blood flow, and occasionally accompanied by pain. [23] Medical practitioners prescribe recommended doses up to 2000 mg per day of niacin in either immediate-release or slow-release formats, to lower plasma triglycerides and low-density lipiprotein cholesterol. [24]
Vitamin B5NoneNo toxicity known.
Vitamin B6US UL = 100 mg/day; EU UL = 25 mg/daySee Megavitamin-B6 syndrome for more information.
Vitamin B7NoneNo toxicity known.
Folate1 mg/day [25] Masks B12 deficiency, which can lead to permanent neurological damage. [25]
Vitamin B12None established [26] Skin and spinal lesions. Acne-like rash [causality is not conclusively established]. [26] [27]

Discovery

VitaminNameDiscovererDateNotes
Vitamin B1 Thiamine Umetaro Suzuki 1910Failed to gain publicity.
Casimir Funk 1912
Vitamin B2 Riboflavin D.T Smith and E.G Hendrick1926 Max Tishler invented methods for synthesizing it.
Vitamin B3 Niacin Conrad Elvehjem 1937
Vitamin B5 Pantothenic acid Roger J. Williams 1933
Vitamin B6 Pyridoxine etc. Paul Gyorgy 1934
Vitamin B7 Biotin Research by multiple independent groups in the early 1900s; credits for discovery include Margaret Averil Boas (1927), [28] Paul Gyorgy (1939, as Vitamin H), [29] and Dean Burk. [30]
Vitamin B9 Folic acid Lucy Wills 1933
Vitamin B12 Cobalamins Five people have been awarded Nobel Prizes for direct and indirect studies of vitamin B12: George Whipple, George Minot and William Murphy (1934), Alexander R. Todd (1957), and Dorothy Hodgkin (1964). [31]

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.

Related Research Articles

<span class="mw-page-title-main">Riboflavin</span> Vitamin and supplement

Riboflavin, also known as vitamin B2, is a vitamin found in food and sold as a dietary supplement. It is essential to the formation of two major coenzymes, flavin mononucleotide and flavin adenine dinucleotide. These coenzymes are involved in energy metabolism, cellular respiration, and antibody production, as well as normal growth and development. The coenzymes are also required for the metabolism of niacin, vitamin B6, and folate. Riboflavin is prescribed to treat corneal thinning, and taken orally, may reduce the incidence of migraine headaches in adults.

<span class="mw-page-title-main">Thiamine</span> Chemical compound

Thiamine, also known as thiamin and vitamin B1, is a vitamin, an essential micronutrient for humans and animals. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosphorylated forms of thiamine are required for some metabolic reactions, including the breakdown of glucose and amino acids.

<span class="mw-page-title-main">Vitamin</span> Nutrients required by organisms in small amounts

Vitamins are organic molecules that are essential to an organism in small quantities for proper metabolic function. Essential nutrients cannot be synthesized in the organism in sufficient quantities for survival, and therefore must be obtained through the diet. For example, vitamin C can be synthesized by some species but not by others; it is not considered a vitamin in the first instance but is in the second. Most vitamins are not single molecules, but groups of related molecules called vitamers. For example, there are eight vitamers of vitamin E: four tocopherols and four tocotrienols.

<span class="mw-page-title-main">Pantothenic acid</span> Chemical compound

Pantothenic acid (vitamin B5) is a B vitamin and an essential nutrient. All animals need pantothenic acid in order to synthesize coenzyme A (CoA), which is essential for cellular energy production and for the synthesis and degradation of proteins, carbohydrates, and fats.

Vitamin B<sub>6</sub> Class of chemically related vitamins

Vitamin B6 is one of the B vitamins, and thus an essential nutrient. The term refers to a group of six chemically similar compounds, i.e., "vitamers", which can be interconverted in biological systems. Its active form, pyridoxal 5′-phosphate, serves as a coenzyme in more than 140 enzyme reactions in amino acid, glucose, and lipid metabolism.

<span class="mw-page-title-main">Folate</span> Vitamin B9; nutrient essential for DNA synthesis

Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and storage. Folate is required for the body to make DNA and RNA and metabolise amino acids necessary for cell division and maturation of blood cells. As the human body cannot make folate, it is required in the diet, making it an essential nutrient. It occurs naturally in many foods. The recommended adult daily intake of folate in the U.S. is 400 micrograms from foods or dietary supplements.

<span class="mw-page-title-main">Biotin</span> Chemical compound (vitamin B7)

Biotin (also known as vitamin B7 or vitamin H) is one of the B vitamins. It is involved in a wide range of metabolic processes, both in humans and in other organisms, primarily related to the utilization of fats, carbohydrates, and amino acids. The name biotin, borrowed from the German Biotin, derives from the Ancient Greek word βίοτος (bíotos; 'life') and the suffix "-in" (a suffix used in chemistry usually to indicate 'forming'). Biotin appears as a white crystalline solid that looks like needles.

A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excreted by cells to create non-cellular structures, such as hair, scales, feathers, or exoskeletons. Some nutrients can be metabolically converted to smaller molecules in the process of releasing energy, such as for carbohydrates, lipids, proteins, and fermentation products, leading to end-products of water and carbon dioxide. All organisms require water. Essential nutrients for animals are the energy sources, some of the amino acids that are combined to create proteins, a subset of fatty acids, vitamins and certain minerals. Plants require more diverse minerals absorbed through roots, plus carbon dioxide and oxygen absorbed through leaves. Fungi live on dead or living organic matter and meet nutrient needs from their host.

Vitamin deficiency is the condition of a long-term lack of a vitamin. When caused by not enough vitamin intake it is classified as a primary deficiency, whereas when due to an underlying disorder such as malabsorption it is called a secondary deficiency. An underlying disorder can have 2 main causes:

<span class="mw-page-title-main">Dietary supplement</span> Product providing additional nutrients

A dietary supplement is a manufactured product intended to supplement a person's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources, or that are synthetic. The classes of nutrient compounds in supplements include vitamins, minerals, fiber, fatty acids, and amino acids. Dietary supplements can also contain substances that have not been confirmed as being essential to life, and so are not nutrients per se, but are marketed as having a beneficial biological effect, such as plant pigments or polyphenols. Animals can also be a source of supplement ingredients, such as collagen from chickens or fish for example. These are also sold individually and in combination, and may be combined with nutrient ingredients. The European Commission has also established harmonized rules to help insure that food supplements are safe and appropriately labeled.

<span class="mw-page-title-main">Choline</span> Chemical compound and essential nutrient

Choline ( KOH-leen) is an essential nutrient for humans and many other animals, which was formerly classified as a B vitamin (vitamin B4). It is a structural part of phospholipids and a methyl donor in metabolic one-carbon chemistry. The compound is related to trimethylglycine in the latter respect. It is a cation with the chemical formula [(CH3)3NCH2CH2OH]+. Choline forms various salts, for example choline chloride and choline bitartrate.

<span class="mw-page-title-main">Nutrition and pregnancy</span> Nutrient intake and dietary planning undertaken before, during and after pregnancy

Nutrition and pregnancy refers to the nutrient intake, and dietary planning that is undertaken before, during and after pregnancy. Nutrition of the fetus begins at conception. For this reason, the nutrition of the mother is important from before conception as well as throughout pregnancy and breastfeeding. An ever-increasing number of studies have shown that the nutrition of the mother will have an effect on the child, up to and including the risk for cancer, cardiovascular disease, hypertension and diabetes throughout life.

Food fortification or enrichment is the process of adding micronutrients to food. It can be carried out by food manufacturers, or by governments as a public health policy which aims to reduce the number of people with dietary deficiencies within a population. The predominant diet within a region can lack particular nutrients due to the local soil or from inherent deficiencies within the staple foods; the addition of micronutrients to staples and condiments can prevent large-scale deficiency diseases in these cases.

Vitamin B<sub><small>12</small></sub> Vitamin used in animal cells metabolism

Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. It is one of eight B vitamins. It is required by animals, which use it as a cofactor in DNA synthesis, and in both fatty acid and amino acid metabolism. It is important in the normal functioning of the nervous system via its role in the synthesis of myelin, and in the circulatory system in the maturation of red blood cells in the bone marrow. Plants do not need cobalamin and carry out the reactions with enzymes that are not dependent on it.

Vitamins occur in a variety of related forms known as vitamers. A vitamer of a particular vitamin is one of several related compounds that performs the functions of said vitamin and prevents the symptoms of deficiency of said vitamin.

<span class="mw-page-title-main">Nutritional neuroscience</span> Scientific discipline

Nutritional neuroscience is the scientific discipline that studies the effects various components of the diet such as minerals, vitamins, protein, carbohydrates, fats, dietary supplements, synthetic hormones, and food additives have on neurochemistry, neurobiology, behavior, and cognition.

<span class="mw-page-title-main">Vegan nutrition</span> Nutritional and human health aspects of vegan diets

Vegan nutrition refers to the nutritional and human health aspects of vegan diets. A well-planned vegan diet is suitable to meet all recommendations for nutrients in every stage of human life. Vegan diets tend to be higher in dietary fiber, magnesium, folic acid, vitamin C, vitamin E, and phytochemicals; and lower in calories, saturated fat, iron, cholesterol, long-chain omega-3 fatty acids, vitamin D, calcium, zinc, and vitamin B12.

Relatively speaking, the brain consumes an immense amount of energy in comparison to the rest of the body. The mechanisms involved in the transfer of energy from foods to neurons are likely to be fundamental to the control of brain function. Human bodily processes, including the brain, all require both macronutrients, as well as micronutrients.

Vitamin B<sub>3</sub> Class of chemically related vitamers

Vitamin B3, colloquially referred to as niacin, is a vitamin family that includes three forms, or vitamers: niacin (nicotinic acid), nicotinamide (niacinamide), and nicotinamide riboside. All three forms of vitamin B3 are converted within the body to nicotinamide adenine dinucleotide (NAD). NAD is required for human life and people are unable to make it within their bodies without either vitamin B3 or tryptophan. Nicotinamide riboside was identified as a form of vitamin B3 in 2004.

In general, cognitive support diets are formulated to include nutrients that have a known role in brain development, function and/or maintenance, with the goal of improving and preserving mental processes such as attentiveness, short-term and long-term memory, learning, and problem solving. Currently, there is very little conclusive research available regarding cat cognition as standardized tests for evaluating cognitive ability are less established and less reliable than cognitive testing apparatus used in other mammalian species, like dogs. Much of what is known about feline cognition has been inferred from a combination of owner-reported behaviour, brain necropsies, and comparative cognitive neurology of related animal models. Cognition claims appear primarily on kitten diets which include elevated levels of nutrients associated with optimal brain development, although there are now diets available for senior cats that include nutrients to help slow the progression of age-related changes and prevent cognitive decline. Cognition diets for cats contain a greater portion of omega-3 fatty acids, especially docosahexaenoic acid (DHA) as well as eicosapentaenoic acid (EPA), and usually feature a variety of antioxidants and other supporting nutrients thought to have positive effects on cognition.

References

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  6. 1 2 Woolston C (14 July 2008). "B vitamins don't boost energy drinks' power". Los Angeles Times . Archived from the original on 19 October 2008. Retrieved 8 October 2008.
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  8. ↑ Thornalley PJ, Babaei-Jadidi R, Al Ali H, Rabbani N, Antonysunil A, Larkin J, et al. (October 2007). "High prevalence of low plasma thiamine concentration in diabetes linked to a marker of vascular disease". Diabetologia. 50 (10): 2164–70. doi:10.1007/s00125-007-0771-4. PMC   1998885 . PMID   17676306.
  9. ↑ Shaw GM, Schaffer D, Velie EM, Morland K, Harris JA (May 1995). "Periconceptional vitamin use, dietary folate, and the occurrence of neural tube defects". Epidemiology. 6 (3): 219–26. doi: 10.1097/00001648-199505000-00005 . PMID   7619926. S2CID   2740838.
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  13. ↑ National Academy of Sciences. Institute of Medicine. Food and Nutrition Board, ed. (1998). "Chapter 6 - Niacin". Dietary Reference Intakes for Tjiamine, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin and Choline. Washington, DC: National Academy Press.
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  16. ↑ "Vitamin B6". Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis, OR. May 2014. Archived from the original on 14 March 2018. Retrieved 7 March 2017.
  17. ↑ Schnepp, Zoe (2002). "Biotin". University of Bristol. Retrieved 17 September 2012– via bris.ac.uk.
  18. ↑ National Academy of Sciences. Institute of Medicine. Food and Nutrition Board, ed. (1998). "Chapter 8 - Folate". Dietary Reference Intakes for Thiamine, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin and Choline. Washington, DC: National Academy Press.
  19. ↑ Schnepp, Zoe (2002). "Vitamin B12". University of Bristol. Retrieved 16 September 2012– via bris.ac.uk.
  20. ↑ Sardesai, Vishwanath (11 April 2003). Introduction to Clinical Nutrition. CRC Press. ISBN   978-0-203-91239-3.
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  22. 1 2 National Academy of Sciences. Institute of Medicine. Food and Nutrition Board., ed. (1998). "Chapter 5 - Riboflavin". Dietary Reference Intakes for Thiamine, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, D.C.: National Academy Press. pp. 87–122. ISBN   978-0-309-06411-8. Archived from the original (PDF) on 18 June 2009. Retrieved 17 June 2009.
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