Researchers have discovered an enzyme that, when found at high levels and alongside low levels of high-density lipoprotein (HDL) cholesterol, reduces the risk for cardiovascular mortality.

The enzyme―glutathione peroxidase, or GPx3―is a natural antioxidant that reduces oxidized lipids to their nontoxic metabolites. The findings are published in the journal PLoS One.

“In our study, we found that people with high levels of the GPx3 enzyme and low levels of good cholesterol were six times less likely to develop cardiovascular disease than people with low levels of both,” said lead author Jordan Holtzman, University of Minnesota Medical School, US. “This GPx3 enzyme gives us a good reason to believe that natural antioxidants like GPx3 are good for heart health.”

The researchers used data from the Minnesota Heart Survey to determine the GPx3 activity of 130 individuals who had died after 5 to 12 years of follow-up and 240 controls. They then assessed the association between GPx3 activity and cardiovascular mortality risk.

The team found that serum GPx3 activity was inversely and dose-dependently correlated with cardiovascular disease (CVD) mortality, including coronary heart disease, other atherosclerotic disease, and stroke.

Subgroup analysis indicated that this association was only seen in individuals with low HDL cholesterol and was independent of conventional risk factors for CVD.

Indeed, for individuals with below median HDL cholesterol (<38 mg/dl in men and <48 mg/dl in women), those in the first, second, and third quartiles of GPx3 had a 6.08-, 5.00-, and 3.64-fold higher risk for CVD than those in the highest GPx3 quartile.

By contrast, in those at or above the median HDL cholesterol concentration, the risk for CVD mortality across quartiles of GPx3 was constant and similar to the risk seen in those with low HDL cholesterol and high GPx3 activity.

“It is important to point out that people should not rush out to their doctors and demand testing for the GPx3 enzyme,” said Holtzman. “But in time, we hope that measuring this enzyme will be a common blood test when determining whether a patient is at risk for cardiovascular disease, including heart attacks and strokes.”

By Nikki Withers