Vitamin B6 is a water-soluble vitamin that plays several important roles in the body. Also known as pyridoxine, it helps the body make antibodies to fight diseases, helps maintain normal nerve function, makes hemoglobin (hemoglobin carries oxygen in the red blood cells to the tissues), keeps blood sugar in normal ranges and helps in the production of neurotransmitters (1).
It has been shown in some preclinical studies to have neuroprotective, antihypertensive and antitumor effects.
Part of the vitamin B-complex family, vitamin B6 is actually a mixture of 6 inter-convertible pyridine vitamers, or related compounds: pyridoxine, pyridoxamine, pyridoxal, and their 5′-phosphorylated forms.
This vitamin is found in abundance in meats, fish, poultry, shellfish, leafy green vegetables, legumes, fruits and whole grains.
It is rare to have a significant deficiency of B6, although studies indicate many people may be mildly deficient, especially children and the elderly (2).
Even though lab studies show that B6 can have protective effects, high levels can also be toxic and cause nerve damage (3).
Vitamin B6 may be beneficial for the treatment of inflammation. Pyridoxal-5-phosphate, the biologically active form of vitamin B6, is lower in those with inflammatory conditions such as inflammatory bowel disease. In a mouse study, researchers found that moderate supplementation of B6 was associated with a significant suppression of molecular and histological markers of inflammation in the colon.
According to the journal Circulation, low circulating vitamin B6 is associated with elevation of the inflammation marker C-reactive protein (4).
There are also a number of cell culture studies that have suggested several possible mechanisms relating impaired vitamin B6 status with chronic inflammation (5).
Other diseases, such as rheumatoid arthritis, are also associated with reduced vitamin B6 levels.
Vitamin B6 may play a role in preventing cardiovascular disease. A study published in The British Journal of Nutrition, highlights the relationship between low vitamin B6 and cardiovascular disease (CVD) through its link with inflammation.
Sufficient evidence substantiates the theory of atherosclerosis (clogged arteries) as an inflammatory disease, and low plasma vitamin B6 concentrations have been related to increased CVD risk.
More research is warranted to support evidence that a mild vitamin B6 deficiency may put people at-risk for inflammatory-linked diseases such as CVD (6).
Research also shows that high plasma homocysteine concentration is associated with increased risk of atherothrombotic disease. Homocysteine is a common amino acid in the blood; high levels are linked to the early development of heart disease.
The results of one study revealed that homocysteine-lowering treatment with folic acid plus vitamin B6 is associated with a decreased occurrence of abnormal exercise electrocardiography tests, which is consistent with a decreased risk of atherosclerotic coronary events (7).
Vitamin B6 may lower the risk of certain cancers. Studies are underway to determine the role this vitamin plays in preventing cancer. In one such study, researchers found that vitamin B6 may be effective in treating colorectal cancer, particularly among women who drink alcohol (8).
According to reporting from Memorial Sloan Kettering Cancer Center, lower intake of dietary vitamin B6 is associated with increased risk of gastric adenocarcinoma and pancreatic cancer.
Not all studies, however, have shown favorable results. Conclusions from the Women’s Health Study indicated that supplementation with vitamins B6, B12 and folate did not decrease breast cancer risk, nor did it have an effect on overall risk of invasive cancer or breast cancer.
In addition, long-term vitamin B6 supplement intake is associated with increased risk of lung cancer, especially in male smokers.
Vitamin B6 may lower blood pressure. In one study, the inclusion of a vitamin B6 supplement (five times the normal intake) in the diets of obese and lean rats resulted in a reduction of the hypertension (high blood pressure) in the obese strain. Removal of the vitamin B6 supplement from the diet of these obese rats resulted in the return of hypertension within 2 weeks.
Similar changes in systolic blood pressure were also observed in the lean controls treated with vitamin B6. The ingestion of sucrose by male rats resulted in modest elevation of systolic blood pressure that was reduced by the inclusion of the vitamin B6 supplement in their diet (9).
Systolic blood pressure measures the pressure in the blood vessels when the heart beats; diastolic blood pressure measures the pressure in the blood vessels when the heart rests between beats (10).
Vitamin B6 may help to reduce symptoms of depression. Some studies suggest that a low level of the phosphate derivative of vitamin B6 in plasma, pyridoxal phosphate, is associated with symptoms of depression (11).
Vitamin B6 helps the body make several neurotransmitters, chemicals that carry signals from one nerve cell to another. It is needed for normal brain development and function, and helps the body make the hormones serotonin and norepinephrine, which influence mood. Low levels of serotonin are associated with depression (12).
A study of 3503 adults (age 65 and over) from the Chicago Health and Aging project, supported the hypothesis that high total intakes of vitamins B6 and B12 are protective of depressive symptoms over time in older adults (13).
Researchers stress the need for more in-depth studies.
Vitamin B6 may be an effective treatment for tardive dyskinesia. Tardive dyskinesia (TD) is a serious side effect that may occur with certain medications used to treat mental illness; symptoms include repetitive, jerking movements that occur in the face, neck and tongue (14).
The results of a 26-week study conducted on 50 inpatients with schizophrenia or schizoaffective disorder and TD showed that supplementation of the vitamin appears to be effective in reducing symptoms of TD.
The specific mechanisms by which vitamin B6 reduces symptoms of TD are not clear (15).
Long-term intake of high doses of vitamin B6 can lead to nerve problems; unexplained symptoms of nerve pain, lack of muscle control, or poor physical coordination may be a sign of excess B6.
People who eat a balanced diet should meet the daily requirement for vitamin B6 without taking a supplement (16).
Consult with a physician to determine if supplementation is necessary and the proper dosage.
Vitamin B6 is a water-soluble vitamin necessary for many physiological processes in the human body. It helps the body make antibodies to fight diseases, helps maintain normal nerve function, makes hemoglobin (hemoglobin carries oxygen in the red blood cells to the tissues), keeps blood sugar in normal ranges and helps in the production of neurotransmitters.
It is being researched for its ability to treat inflammation, prevent cardiovascular disease and certain types of cancer and help reduce symptoms of depression.
This vitamin is found in abundance in meats, fish, poultry, shellfish, leafy green vegetables, legumes, fruits and whole grains. It is rare to have a significant deficiency of B6.
Long-term intake of high doses of vitamin B6 can lead to nerve problems.