Vitamin B Complex
chemical compounds
vitamin B complex, several vitamins that traditionally have been grouped together because of loose similarities in their properties, their distribution in natural sources, and their physiological functions, which overlap considerably. All the B vitamins, like vitamin C, are soluble in water, in contrast to the fat-soluble vitamins A, D, E, and K.
Most of the B vitamins have been recognized as coenzymes (substances that participate with enzymes in accelerating the interconversion of chemical compounds), and they all appear to be essential in facilitating the metabolic processes of all forms of animal life. The complex includes pantothenic acid, niacin, biotin, folic acid, riboflavin (vitamin B2), thiamin (vitamin B1), vitamin B6, and vitamin B12 (cobalamin). The compounds carnitine, choline, lipoic acid, inositol, and para-aminobenzoic acid perform analogous functions in animals and have been included among the B vitamins by certain authorities. See table of the vitamins.
vitamin
alternative names/forms
biological function
symptoms of deficiency
Water-soluble
thiamin
vitamin B1
component of a coenzyme in carbohydrate metabolism; supports normal nerve function
impairment of the nerves and heart muscle wasting
riboflavin
vitamin B2
component of coenzymes required for energy production and lipid, vitamin, mineral, and drug metabolism; antioxidant
inflammation of the skin, tongue, and lips; ocular disturbances; nervous symptoms
niacin
nicotinic acid, nicotinamide
component of coenzymes used broadly in cellular metabolism, oxidation of fuel molecules, and fatty acid and steroid synthesis
skin lesions, gastrointestinal disturbances, nervous symptoms
vitamin B6
pyridoxine, pyridoxal, pyridoxamine
component of coenzymes in metabolism of amino acids and other nitrogen-containing compounds; synthesis of hemoglobin, neurotransmitters; regulation of blood glucose levels
dermatitis, mental depression, confusion, convulsions, anemia
folic acid
folate, folacin, pteroylglutamic acid
component of coenzymes in DNA synthesis, metabolism of amino acids; required for cell division, maturation of red blood cells
impaired formation of red blood cells, weakness, irritability, headache, palpitations, inflammation of mouth, neural tube defects in fetus
vitamin B12
cobalamin, cyanocobalamin
cofactor for enzymes in metabolism of amino acids (including folic acid) and fatty acids; required for new cell synthesis, normal blood formation, and neurological function
smoothness of the tongue, gastrointestinal disturbances, nervous symptoms
pantothenic acid
as component of coenzyme A, essential for metabolism of carbohydrate, protein, and fat; cofactor for elongation of fatty acids
weakness, gastrointestinal disturbances, nervous symptoms, fatigue, sleep disturbances, restlessness, nausea
biotin
cofactor in carbohydrate, fatty acid, and amino acid metabolism
dermatitis, hair loss, conjunctivitis, neurological symptoms
vitamin C
ascorbic acid
antioxidant; synthesis of collagen, carnitine, amino acids, and hormones; immune function; enhances absorption of non-heme iron (from plant foods)
swollen and bleeding gums, soreness and stiffness of the joints and lower extremities, bleeding under the skin and in deep tissues, slow wound healing, anemia
Fat-soluble
vitamin A
retinol, retinal, retinoic acid, beta-carotene (plant version)
normal vision, integrity of epithelial cells (mucous membranes and skin), reproduction, embryonic development, growth, immune response
ocular disturbances leading to blindness, growth retardation, dry skin, diarrhea, vulnerability to infection
vitamin D
calciferol, calatriol (1,25-dihydroxy vitamin D1 or vitamin D hormone), cholecalciferol (D3; plant version), ergocalciferol (D2; animal version)
maintenance of blood calcium and phosphorus levels, proper mineralization of bones
defective bone growth in children, soft bones in adults
vitamin E
alpha-tocopherol, tocopherol, tocotrienol
antioxidant; interruption of free radical chain reactions; protection of polyunsaturated fatty acids, cell membranes
peripheral neuropathy, breakdown of red blood cells
vitamin K
phylloquinone, menaquinone, menadione, naphthoquinone
synthesis of proteins involved in blood coagulation and bone metabolism
impaired clotting of the blood and internal bleeding
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