Health freaks know that high levels of total cholesterol and LDL cholesterol can increase the risk of heart attacks. Now, scientists have discovered a little-known type of cholesterol which may prove to be the most lethal of all.
Cholesterol called oxycholesterol is virtually unknown to the public and may be the most serious cardiovascular health threat of all.
Fried and processed food, particularly fast food, contains high amounts of oxycholesterol.
The researchers hope their findings raise public awareness about oxycholesterol, including foods with the highest levels of the substance and other foods that can combat oxycholesterol's effects.
"Total cholesterol, low-density lipoprotein cholesterol (LDL), and the heart-healthy high-density lipoprotein cholesterol (HDL) are still important health issues," says study leader Zhen-Yu Chen, Ph.D., of Chinese University of Hong Kong.
"But the public should recognize that oxycholesterol is also important and cannot be ignored. Our work demonstrated that oxycholesterol boosts total cholesterol levels and promotes atherosclerosis ["hardening of the arteries"] more than non-oxidized cholesterol," the expert added.
In the study, Chen's group measured the effects of a diet high in oxycholesterol on hamsters, often used as surrogates for humans in such research. Blood cholesterol in hamsters fed oxycholesterol rose up to 22 percent more than hamsters eating non-oxidized cholesterol. The oxycholesterol group showed greater deposition of cholesterol in the lining of their arteries and a tendency to develop larger deposits of cholesterol. These fatty deposits, called atherosclerotic plaques, increase the risk for heart attack and stroke.
Most importantly, according to Chen, oxycholesterol had undesirable effects on "artery function." Oxycholesterol reduced the elasticity of arteries, impairing their ability to expand and carry more blood. That expansion can allow more blood to flow through arteries that are partially blocked by plaques, potentially reducing the risk that a clot will form and cause a heart attack or stroke.
But a healthy diet rich in antioxidants can counter these effects, Chen said, noting that these substances may block the oxidation process that forms oxycholesterol.