B vitamins are water-soluble vitamins. Because they are water-soluble, they are excreted through urine and can't be stored by the body. You need a continuous supply through diet. The B vitamins are thiamine, or B1, riboflavin, or B2, niacin, or B3, pantothenic acid, or B5, B6, biotin, or B7, B12 and folic acid.
B vitamins are found in sources of protein like fish, poultry, meat, eggs and dairy products, according to the National Institutes of Health. They're also found in whole grains, leafy green vegetables, beans and peas. A slice of whole wheat bread contains thiamine, riboflavin, niacin, vitamin B6, folate, biotin and pantothenic acid. Spinach contains thiamine, riboflavin, niacin, vitamin B6, folate and biotin.
The B vitamins are needed for metabolic activity. They help the body use energy from foods. They're also involved in making red blood cells, which carry oxygen to every part of the body. Vitamin B6 helps the body use protein. Vitamin B12 helps maintain the central nervous system. Biotin is needed for the metabolism of proteins and carbohydrates and the production of hormones and cholesterol. Niacin maintains healthy skin and nerves. Folate is needed to produce DNA. Pantothenic acid is required for the production of hormones and cholesterol. Riboflavin helps the body grow. Thiamin is required for normal heart function and nerve health.
Thiamine and riboflavin may protect against cataracts, according to the Linus Pauling Institute at Oregon State University. Further research is needed to determine riboflavin's role in migraine prevention. Niacin intake may be associated with lower risk of mouth, throat and esophageal cancers. Nicotinamide, a derivative of niacin, may protect against insulin-dependent diabetes mellitus. Further research needs to determine if biotin protects against birth defects. If the body doesn't have enough vitamin B12, vitamin B6 or folate, vitamin deficiency anemia occurs. Vitamin B12 may also protect against cancer, neural tube defects, dementia and depression. Folate prevents neural tube defects. It may protect against colorectal cancer and breast cancer, although high doses may stimulate tumor growth. It may also reduce cognitive decline in the elderly.
Niacin may lower cholesterol and risk of heart disease, but should be consumed in small doses under the care of a physician. Pantethine, a pantothenic acid derivative, may also lower cholesterol. Vitamins B12, B6 and folate are needed to convert the amino acid homocysteine into methionine. If homocysteine isn't turned into methionine, homocysteine levels increase, increasing risk of heart attack, stroke and peripheral vascular disease, according to the American Heart Association.
More research is needed to determine if thiamine can be a used to treat Alzheimer's disease or maintain cardiac function in patients with congestive heart failure, according to the Linus Pauling Institute at Oregon State University. Niacin may protect against AIDS in people with HIV. Further research is needed to determine if pantothenic acid can accelerate wound healing, according to the Linus Pauling Institute. Vitamin B6 has been studied as a treatment for premenstrual syndrome, the side effects of birth control pills and depression, but more research needs to be done to form a conclusion. Biotin needs further study as a potential treatment for diabetes mellitus. It may also increase thickness of brittle fingernails.