B Vitamins in Brief: Food Sources, Benefits, and Deficiency

B vitamins are water-soluble vitamins and, except for B12, are not stored in the body. They play important roles in cellular metabolism. Because they are chemically different, they have different effects. A food group may contain several B vitamins. With appropriate dietary choices and easier access to food, deficiencies are not particularly common today. Therefore, except in certain special circumstances, we do not recommend vitamin supplements unless a low level has been demonstrated by a blood test.

There Are 8 Different B Vitamins

Vitamin B1 — Thiamine

The active form of vitamin B1 is thiamine pyrophosphate (TPP). It is abundant in grains and also found in yeast, brown rice, vegetables, fruit, sunflower seeds, beef, and seafood. Deficiency may cause beriberi, Wernicke encephalopathy, depression, anxiety, and congestive heart failure. Besides being a strong antioxidant, it shows protection against damage to small blood vessels caused by diabetes.

Vitamin B2 — Riboflavin

Vitamin B2 is riboflavin, whose active form is riboflavin-5-phosphate. Like vitamin B1, it is found in grains. Other sources include salmon, almonds, broccoli, spinach, whole milk, and eggs. It is needed for energy production and is used for cataract prevention and in acne and migraine treatment.

Vitamin B3 — Niacin

Vitamin B3 is called niacin. Its active form is nicotinamide, or niacinamide, which is important for energy metabolism. It is abundant in peanuts, brown rice, fish, chicken, and liver. It helps keep cholesterol low. There are also chemopreventive effects against skin cancer reported in studies .

Vitamin B5 — Pantothenic Acid

Vitamin B5 is called pantothenic acid. It is found in grains, liver, mushrooms, milk, legumes, meat, vegetables, nuts, and avocado. It is used in steroid hormone synthesis in the adrenal glands. Deficiency may cause dermatitis, or skin lesions, and acne.

Vitamin B6 — Pyridoxine

The active form of vitamin B6, pyridoxine, is pyridoxine-5-phosphate (P5P). Vitamin B6 is an enzyme involved in amino acid production and DNA repair and plays a role in synthesizing neurotransmitters used for nerve cell communication. It is found in lentils, trout, molasses, blueberries, poultry, and organ meats. Vitamin B6 deficiency may lead to oxalate kidney stones. Vitamin B6 is known to help nausea and vomiting during pregnancy, so vitamin B6 is recommended for pregnancy-related vomiting. Vitamin B6 is similarly recommended as a dietary supplement for carpal tunnel syndrome. It is also being investigated for preventing and treating chemotherapy-associated neuropathy, nerve damage in the hands and feet, but satisfactory results have not yet been demonstrated.

Vitamin B7 — Biotin

Vitamin B7 is called biotin. Sources include egg yolk, organ meats, milk, barley, yeast, and royal jelly. Deficiency causes brittle nails and hair loss. It is added to treatment for seborrheic dermatitis affecting infants’ scalps. It helps reduce insulin resistance in people with diabetes and is added to insulin and other diabetes medications.

Vitamin B9 — Folic Acid

Vitamin B9 is called folic acid, or folate. Its active form is 5-methyltetrahydrofolate. Sources include leafy green vegetables, fruit, citrus fruit, legumes, spinach, salmon, eggs, and dairy milk. Some studies have identified an association between depression and low folate. Older adults receiving folic acid supplements have shown better memory and mental agility. It is used in depression, dementia, and prevention of gum disease. Babies of pregnant women with folate deficiency have an increased likelihood of neural tube defects. Vitamin B9 supplementation is therefore recommended during pregnancy.

Vitamin B12 — Cobalamin

Vitamin B12 is called cobalamin. Its active form is methylcobalamin. It is found in liver, beef, trout, salmon, eggs, milk, and shellfish. Vitamin B12 deficiency causes fatigue. Vitamin B12 reduces the effects of depression and is added to the diet of patients with dermatitis or oral problems. Vitamin B12 deficiency is more frequent than deficiencies of the other B vitamins.

To be absorbed, vitamin B12 must combine with a protein called intrinsic factor, produced in the stomach lining. In conditions such as gastritis or stomach ulcers, insufficient intrinsic factor is produced and B12 cannot be fully absorbed. This is called pernicious anemia. In addition, people who have part of their stomach removed because of stomach cancer cannot absorb B12 and receive vitamin B12 injections into the buttock at intervals, for example every 9 weeks.

Vitamins B12 and B9 (folate) are important for development, differentiation, and function of the central nervous system. They participate in the methionine–homocysteine pathway, which supplies methyl groups for DNA and protein synthesis. In vitamin B12 deficiency, remethylation of homocysteine to methionine decreases, resulting in hyperhomocysteinemia.