Primary Role Of B-complex Vitamins

The B complex represents a family of chemicals known as the B vitamins. The B complex is composed of vitamins B1, B2, B3, B5, B6, B7, B9 and B12. Each plays a key role in cellular maintenance, where some B-vitamins are known to have several physiological functions. The importance of maintaining proper daily levels of B-vitamins is illustrated when a person is either deficient or takes excessive B-vitamin supplements, resulting in a number of dysfunctions.

Birth Defects

Vitamin B9, also called folic acid, is essential for preventing birth defects. It is necessary during embryonic development so that the central nervous system can grow and form normally. If the pregnant mother is deficient in vitamin B9, the result can be the birth defects anencephaly and spina bifida. These malformations occur when the brain and spinal cord form partially or totally outside of the skull or spinal column. The result can be severe neurological dysfunction or death of the fetus.

Nervous System

Certain neurological functions require B-vitamins. A deficiency in vitamin B6, also called pyridoxine, may be related to the onset of seizures, headaches, depression, Parkinson's disease and many other neurological conditions. The vitamin is essential for making the brain neurotransmitters serotonin and dopamine, which are needed for neurons to communicate. Vitamin B12, also called methylcobalamin, helps prevent neurological problems and can assist in the recovery from some effects of Bell's palsy. When a diet is deficient in vitamin B12, the result can be conditions such as spasticity in the arms and legs, walking disability or bowel and bladder problems. Vitamin B1, also called thiamine, can aid in the brain's cognitive abilities.

Blood Glucose

Maintaining blood glucose within a normal range throughout the day is an important function of vitamin B6. When the caloric intake of the body starts to drop, vitamin B6 helps turn stored carbohydrates and nutrients into glucose to keep blood glucose levels normal. A diet insufficient in vitamin B6 can hinder the body's ability to maintain normal glucose levels in the blood. Supplements will not improve this ability if the person is already well-nourished, reports the National Institutes of Health.

Other Functions

When the recommended daily amounts of vitamin B9 are met, the American Cancer Society concludes it can lower the risk of cancer. Vitamin B6 is required to metabolize certain enzymes and make proteins. Vitamin B12 and vitamin B5, also called pantothenic acid, help keep the body from becoming anemic. Vitamin B5 also assists with the normal function of the immune and gastrointestinal systems. Vitamins B12 and B2, also called riboflavin, are necessary for the body to manufacture red blood cells. Blood circulation is enhanced with vitamin B1.

Recommended Dietary Allowance (RDA)

The U.S. Department of Agriculture publishes the RDA for most B-vitamins. For pregnant women, the RDA of B9 is 600 mcg. The RDA of B12 is 2.4 mcg in all adults. The RDA of B6 is 1.3 mg for adults 19 to 50, and 1.5 to 1.7 mg for adults over 50. The adult RDA of vitamin B1 is 1.1 to 1.2 mg; vitamin B2, 1.1 to 1.3 mg; and vitamin B5, 5 to 7 mg.