B vitamins are essential nutrients required to build healthy cells and are involved in many key biological processes in the body including energy metabolism. These water-soluble nutrients have been shown to be critical to the function of the brain, heart, immune system, liver, and every other cell or tissue in the human body. Though found in a variety of foods, especially green leafy vegetables and eggs, supplementation makes sense in order to provide optimum daily intake of these nutrients.

What is a B Vitamin Complex?

There are eight official B vitamins. These include thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6)biotin (B7)folate (B9), and cobalamin (B12). A B vitamin complex refers to a dietary supplement that contains a combination of two or more B vitamins. While each B vitamin has a unique role in human nutrition, they work together in many vital functions. Hence, there is tremendous synergy and interactions when they are used together. B vitamin complex supplements are often promoted for their ability to improve energy production, prevent the buildup of intermediate metabolites in the body like homocysteine that can cause damage to cells and tissue, support immune function, offset the negative effects of stress, boost mood, and promote detoxification reactions.

Here is a brief description of each B vitamin and their key biological roles.

Thiamin (B1

Thiamin was the first B vitamin discovered, hence its designation as vitamin B1. Thiamin is essential for proper energy production in every cell of the body, but especially in the heart and brain. Severe thiamin deficiency was discovered as the cause of a syndrome known as "beriberi." Symptoms include mental confusion, muscle wasting (dry beriberi), fluid retention (wet beriberi), high blood pressure, difficulty walking, and heart disturbances. Thiamin levels are depleted by many drugs, especially diuretics used for high blood pressure.

Riboflavin (B2

Riboflavin functions in two very important enzymes involved in the production energy. Riboflavin deficiency is characterized by cracking of the lips and corner of the mouth; an inflamed tongue; visual disturbances such as sensitivity to light and loss of visual acuity; cataract formation; burning and itching of the eyes, lips, mouth and tongue; and other signs of disorders of mucous membranes. Low levels of riboflavin have been linked to some cancer, cataracts, migraine headaches, and sickle cell anemia.

Niacin (B3)

Niacin and as well as another form of vitamin B3, nicotinamide, work as a part of an enzyme that is crucial to life. When vitamin Blevels are low it can lead to a condition known as pellagra that is characterized by the presence of dermatitis, diarrhea, and dementia. Niacin is often supplemented to support cholesterol levels at higher dosages (e.g., 2-3 g daily) while niacinamide is often recommended to support joint health. At dosages higher than 100 mg, niacin often causes skin flushing, while nicotinamide does not.  

Pantothenic acid (B5

Pantothenic acid is utilized in the manufacture of coenzyme A (CoA) and acyl carrier protein (ACP) - two compounds that play a critical role in the utilization of fats and carbohydrates in energy production as well as the manufacture of adrenal hormones and red blood cells. Pantothenic acid supplementation is often recommended by nutritionally oriented physicians to support adrenal function and combat stress.

Pyridoxine (B6)

B6 is an extremely important B vitamin involved in the formation of body proteins and structural compounds, chemical transmitters in the nervous system, red blood cells, and hormone-like substances known as prostaglandins that control many bodily functions. Pyridoxine is also critical in maintaining hormonal balance and proper immune function. Deficiency of vitamin B6 is characterized by depression, convulsions (especially in children), glucose intolerance, anemia, impaired nerve function, cracking of the lips and tongue, and seborrhea or eczema.

Biotin (B7

Biotin functions in the manufacture and utilization of fats and amino acids. A biotin deficiency in adults is characterized dry, scaly skin; nausea; anorexia; and seborrhea. In infants under six months of age, the symptoms are seborrheic dermatitis (cradle cap), persistent diaper rash, and alopecia (hair loss). Biotin is a popular recommendation to increase the strength of nails and promote healthy hair.

Folate (B9

Folic acid, also known as folate, folacin, and pteroylmonoglutamate, functions together with vitamin B12 in many body processes and is critical to cellular division because it is necessary in DNA synthesis. Without folic acid cells do not divide properly. Deficiency of folic acid during pregnancy has been linked to several birth defects including neural tube defects like spina bifida. Folic acid deficiency is also being linked to depression, atherosclerosis and osteoporosis. Folic acid, vitamin B12, and a form of the amino acid methionine known as SAMe (S-adenosyl-methionine) function as “methyl donors.” They carry and donate methyl molecules to facilitate reactions including the manufacture of DNA and brain neurotransmitters. Folic acid and other methyl donors reduce body concentrations of homocysteine – a toxic intermediate in the body that has been implicated in a variety of health conditions including atherosclerosis, osteoporosis, and certain forms of cancer.

Cobalamin (B12

Vitamin B12 works with folic acid in many body processes including the synthesis of DNA, red blood cells, and the insulation sheath (the myelin sheath) that surrounds nerve cells and speeds the conduction of the signals along with nerve cells. Vitamin B12 is found in significant quantities only in animal foods. Therefore, it appears that it is very important that vegetarians supplement their diets with vitamin B12. A deficiency of vitamin B12 will lead to anemia and affect the brain and nervous system to produce symptoms such as numbness, pins and needles sensations, or a burning feeling in the feet as well as an impaired mental function that in the elderly can mimic Alzheimer's disease. In addition to anemia and nervous system symptoms, a vitamin B12 deficiency will also result in a smooth, beefy red tongue; and diarrhea due to the fact that rapidly reproducing cells such as those which line the mouth and entire gastrointestinal tract will not be able to replicate without vitamin B12

Health Benefits and Uses of Vitamin B Complex Formulations

Vitamin B complex supplements have been shown in clinical research to nutritionally support many health issues. If a person has any of the conditions listed below, they may benefit from taking a supplement that contains B vitamins:

  • Alcohol dependence
  • Canker sores
  • Depression and anxiety
  • Diabetes
  • Elderly individuals
  • Elevated homocysteine levels
  • Headaches (tension or migraine)
  • Learning difficulties
  • Low immune function
  • Poor wound healing
  • Pregnancy and breastfeeding
  • Premenstrual syndrome
  • Smokers
  • Stress
  • Vegans and vegetarians

These are a number of examples of medications that can result in low levels of specific B vitamins:

  • Blood pressure drugs and chemotherapy drugs can lower a person's B1 levels.
  • Anti-seizure medications used for epilepsy can lower B3, B6, and folate levels.
  • Certain cancer drugs can lower folate levels.
  • Certain antibiotics and medicines for ulcers, diabetes, or gastroesophageal reflux disease, or GERD, may lower B12 levels.

Dosage Ranges

Generally, with B vitamin complex formulas dosages are based upon supplying levels of the included B vitamins close to Recommended Dietary Allowance (RDA) levels. Higher potency formulations are available on the market. Generally, B vitamins are without side effects at levels up to ten times the RDA as they are water-soluble nutrients that are excreted through the urine when excess levels are ingested. Certain B vitamins are used in medical treatment, for example, niacin in the treatment of high cholesterol levels. In these instances, extremely high dosages are used and side effects can occur.

The following are RDAs for each of the B vitamins, in milligrams (mg) or micrograms (mcg), according to The National Institutes of Health Office of Dietary Supplements. Older adults may require higher dosages of some B vitamins.




During  pregnancy

During  breastfeeding

Thiamin (Vitamin B1)

1.2 mg

1.1 mg

1.4 mg

1.4 mg


(Vitamin B2)

1.3 mg

1.1 mg

1.4 mg

1.6 mg

Niacin or niacinamide

(Vitamin B3)

16 mg

14 mg

18 mg

17 mg

Pantothenic Acid (Vitamin B5)

5 mg

5 mg

6 mg

7 mg

Pyridoxine (Vitamin B6)

1.3 mg

1.5 mg

1.9 mg

2.0 mg

Biotin (Vitamin B7)

30 mcg

30 mcg

30 mcg

35 mcg

Folate (Vitamin B9)

400 mcg

400 mcg

600 mcg

500 mcg

Cobalamin (Vitamin B12)

2.4 mcg

2.4 mcg

2.6 mcg

2.8 mcg