Participants of another study who subsequently developed CHD tended to have lower mean plasma concentrations of folate, P5P, and vitamin B12 and lower supplemental vitamin use than controls. However, only the mean plasma P5P significantly reduced the risk of CHD. Users of vitamin supplements had higher plasma B-vitamin concentrations than nonusers, suggesting that vitamin supplementation contributed to the association between reduced CHD risk and plasma P5P. The researchers concluded, "Our findings point more strongly to the possibility that vitamin B6 offers independent protection."3 Research has indicated that P5P also may protect against arrhythmia, where the heart may seem to skip a beat or beat irregularly. Arrhythmia is responsible for the damage inflicted in more than two-thirds of heart disease patients and kills more males in the Western world than any other condition. One study reported a P5P deficiency in patients with ischemic heart disease and arrhythmias, a deficiency associated with failure of heart muscle tissue cells.4 In addition to its direct effects on cardiovascular disease, P5P may protect high blood pressure sufferers against coronary artery disease and cerebral vascular disease, two common causes of death or disability in hypertensive patients. In a three-year study of 24 male patients with high blood pressure aged 35-55 years, researchers found that in some of the patients, long-term administration of antihypertensive drugs led to a P5P deficiency.