


The research involved 32,826 women from the Nurses Health Study who provided blood samples between 1989 and 1990. 144 of the women experienced a heart attack between the time they gave their blood sample and July 1998 when the study ended. The vitamin B6 status of these women in 1989-1990 was then compared to the levels in women who had not suffered a heart attack (the control group). The researchers found that levels of pyridoxal-phosphate (PLP), which is the active form of vitamin B6 in the body, were significantly lower in the heart attack group (30.9 pmol/mL) compared to the controls (40.5 pmol/mL).

Furthermore, when the women were divided into quartiles, 43% of heart attack victims were in the bottom quarter for PLP while just 15% were in the top quarter for PLP levels. After adjusting the results for factors including age, cigarette use, history of diabetes and hypertension, aspirin use, and physical activity, the researchers found that the odds of suffering a heart attack were 82% lower in the top quarter compared to the bottom quarter for PLP.

The researchers concluded that “a lower fasting concentration of PLP is significantly associated with an increased risk of MI”.

While dietary intake of vitamin B6 is the primary determinant of PLP levels in the blood, other factors may also play a role such as obesity and physical activity. The above study found a negative correlation between BMI and PLP levels suggesting obese individuals may be at a greater risk of vitamin B6 deficiency than the general population.

The study also found a strong positive correlation between physical activity and PLP levels which is thought to be due to improvements in the utilization of vitamin B6 following exercise. A Japanese study, published in 2001 in the Journal of Nutritional Science and Vitaminology, looked at the effects of exercise on vitamin B6 metabolism in mice who were fed a vitamin B6 restricted diet. The researchers found that exercise normalized the metabolism of several amino acids that are dependent on vitamin B6. Exercise also lowered the amount of vitamin B6 excreted in urine, allowing more of it to be used by the body.

Along with its ability to lower plasma homocysteine levels, vitamin B6 may reduce heart attack risk through other mechanisms. In one study, high levels of vitamin B6 were associated with significantly lower levels of of C-reactive protein. C-reactive protein is a marker of inflammation in the body and has been linked to cardiovascular disease.

If you have first degree relatives who have suffered heart attacks, or you have several risk factors for heart disease, vitamin B6 supplementation may be an option for you. A standard B-vitamin complex typically contains between 50 and 200 mg of vitamin B6. Because vitamin B6 is water-soluble, it is well tolerated even in high doses as the excess is simply excreted in urine. Prolonged, high dose vitamin B6 supplementation in excess of 500 mg per day, can cause some sensory problems as well as numbness and tingling in the extremities caused by nerve damage, however this is typically reversible once supplementation stops.