MAINZ, GERMANY. Glutathione peroxidase is the body's most important internally-generated antioxidant; it is synthesized from glutamate, cysteine and glycine, and its activation requires the presence of adequate amounts of selenium. Glutathione is effective in neutralizing hydrogen peroxide, lipid peroxides, and peroxynitrite – all powerful free radicals that have been implicated in the progression of atherosclerosis and other cardiovascular diseases. Superoxide dismutase (SOD) is another important internally-generated antioxidant that is effective in neutralizing the superoxide anion by converting it to hydrogen peroxide.

A group of Canadian, French and German researchers recently set out to determine if levels (activity) of glutathione and SOD in coronary heart disease patients were indicative of their long-term prognosis. Their study involved 636 patients with symptoms of stable angina (79% of group) or unstable angina. The participants were followed for an average of 4.7 years during which time there were 64 deaths from cardiovascular causes, 21 deaths from other causes, and 19 non-fatal heart attacks. The researchers found that patients with high baseline activity levels of glutathione peroxidase 1 in their red blood cells (greater than 56.31 units per gram of hemoglobin) were three times less likely to have suffered a cardiovascular event than were patients with low activity levels (less than 42.0 units per gram of hemoglobin). The magnitude of the risk reduction was not significantly altered after adjusting for other risk factors for cardiovascular events. Being older, diabetes, low left ventricular ejection fraction, and high blood levels of C-reactive protein, homocysteine and creatinine were all associated with a higher risk whereas a high blood level of HDL (high density lipoprotein) cholesterol and selenium showed a protective effect. The red blood cell level of SOD was not associated with the risk of a future cardiovascular event.

The researchers conclude that a low level of activity of red-cell glutathione peroxidase 1 is independently associated with an increased risk of cardiovascular events in patients with coronary artery disease. They also suggest that increasing glutathione peroxidase 1 activity might lower the risk of cardiovascular events.
Blankenberg, Stefan, et al. Glutathione peroxidase 1 activity and cardiovascular events in patients with coronary artery disease. New England Journal of Medicine, Vol. 349, October 23, 2003, pp. 1605-13

Editor's comment: It is probably not too great a leap of faith to suggest that if high glutathione peroxidase activity levels are beneficial for heart disease patients they may also help the rest of us. The simplest way of increasing red blood cell levels of glutathione is to supplement with vitamin-C. As little as 500 mg/day has been shown to increase glutathione by as much as 50%[1]. In order to ensure adequate glutathione activity it is also a good idea to ensure a selenium intake of 200 micrograms/day.
[1] Johnston, CS, et al. Vitamin C elevates red blood cell glutathione in healthy adults. American Journal of Clinical Nutrition, Vol. 58, July 1993, pp. 103-05