Do Antioxidants Contribute to Heart Disease?
Study Shows Vitamins Raise Levels of Bad Cholesterol in Mice
Antioxidants Boost LDL Cholesterol continued...
His research, published in the Journal of Clinical Investigation, is reportedly the first to link antioxidant vitamins with increased VLDL production. And that's what it makes it important, says one expert.
"The bottom line of this paper is that you shouldn't assume that taking antioxidant vitamins is only going to have beneficial effects on cardiovascular disease," says Ronald M. Krauss, MD, director of atherosclerosis research at Children's Hospital Oakland Research Institute, who was not involved in Fisher's study but wrote an accompanying editorial to it.
"There is no human clinical information -- the research was done on animals -- so this study doesn't offer a recommendation of whether or not you should take antioxidant vitamins," Krauss tells WebMD. "But it provides good background into what may be occurring when one does take antioxidants and help explain some previous findings."
Two years ago, a study of 20,000 people -- already with heart disease risks such as diabetes or blood vessel damage -- showed that taking daily supplements of vitamins C, E, and beta-carotene produced small but noticeable increases in heart disease risk factors such as higher levels of LDL cholesterol and triglycerides, a blood fat linked to heart disease. This study also linked these supplements to lower levels of "good" HDL cholesterol.
"The changes experienced were modest but consistent with mechanisms identified in this paper," Krauss tells WebMD. He says a previous study showed that giving an antioxidant cocktail to people with heart disease reduced the benefits of some cholesterol-lowering drugs.
Last June, after reviewing 15 previous studies involving more than 15,000 people, Cleveland Clinic researchers reported in The Lancet that taking vitamin E did not help prevent heart disease and that taking high levels of beta-carotene supplement actually caused a slight increase in risk of heart attack or stroke. Two weeks later, the U.S. Preventive Services Task Force published its own paper in Annals of Internal Medicine showing there was no evidence that antioxidants, or folic acid, protected against heart disease -- and the agency even warned against taking beta-carotene supplements, which have previously been linked to increased lung cancer risk in smokers.