Detailed information on the B vitamins
|B1, Thiamine or thiamin
Also known as: Vitamin F, Aneurin, Thiamine diphosphate (TDP) – physiologically active form
Role: B1 is a coenzyme that helps the body produce energy, is involved in glucose, amino acid, and alcohol metabolism, and is required for the proper functioning of the nervous system, heart, and muscles.
Sources: Cereals and whole grains, potatoes, pork, seafood, nuts, legumes
Deficiency: In U.S., found primarily with chronic alcoholism. Can cause:
Test name: Thiamine (Thiamine diphosphate) in blood
Also known as: Vitamin G
Role: B2 is a coenzyme involved in energy production and is required for the metabolism of other B vitamins
Sources: Cereals and whole grains, green leafy vegetables, lean meats, dairy products, eggs, enriched breads.
Deficiency: Called ariboflavinosis, usually seen along with other vitamin deficiencies in those with alcoholism, malabsorption, liver disease, and in the elderly.
Test name: Riboflavin, blood or urine
Also known as: Nicotinic acid, Nicotinamide, Vitamin P, Vitamin PP
Role: B3 is involved in enzyme reactions, metabolism, and energy production. It is given in pharmacologic doses to lower LDL-cholesterol and triglycerides and raise HDL-cholesterol
Sources: B3 is found in lean meats, eggs, fish, whole grain cereals and legumes.
Deficiency: Severe deficiency in conjunction with a low-protein diet causes: Pellagra - classic symptoms are dermatitis, diarrhea, and dementia; may also cause a rash in areas exposed to the sun.
Deficiencies also seen with alcoholism, cirrhosis, Hartnup disease, Crohn disease, and carcinoid syndrome. Niacin synthesis requires adequate B6, B2, iron, and copper. Up to 60% of niacin is synthesized from tryptophan.
Toxicity: Pharmacologic doses can cause flushing and headaches. High doses may affect liver.
Test name: Niacin metabolites: N1-Methylnicotinamide, 2-Pyridone in urine thought to be the most reliable measure of intake and body status
|B5, Pantothenic acid
Role: B5 helps break down and use fats, proteins, and carbohydrates.
Sources: Most foods
Deficiency: B5 deficiency is rare as it is widely distributed in foods. Associated with "burning feet" and impaired wound healing.
Test name: Pantothenic acid in blood or urine
|B6, Pyridoxal Phosphate (PLP)
Three main forms: Pyridoxine, pyridoxamine, and pyridoxal
Role: B6 is a coenzyme involved in amino acid metabolism and hemoglobin synthesis. It is also necessary for the nervous system and immune system.
Sources: Pork, fish, chicken, bananas, wheat germ, legumes.
Deficiency: B6 deficiency is rare by itself; adequate B2 is required for the formation of active PLP; may be seen with chronic alcoholism, malabsorption, smoking, and in asthmatics who take theophylline; can cause convulsions and decreased immunity. Both deficiency and toxicity can cause peripheral neuropathy.
Test name: Pyridoxal phosphate (PLP)
Also known as: Vitamin H, Vitamin B-w
Role: B7 is a coenzyme that is necessary for fat, protein, and carbohydrate metabolism and plays a role in hormone production.
Sources: Soy, egg yolks, peanuts, legumes, bananas, and grapefruit. B7 is also made by intestinal bacteria.
Deficiency: Very rare; may occur in those receiving total parenteral nutrition and with some inborn errors of metabolism; can cause weakness, delayed development, rash, hair loss, weakness.
Test names: Biotin in urine
See the article on Vitamin B12 and Folate
|Folic Acid or Folate
Also known as: Vitamin B9, Vitamin M