Healthnotes Newswire — Antioxidants may blunt the effectiveness of a cholesterol-lowering drug regimen, according to a new study in Atherosclerosis, Thrombosis and Vascular Biology,1 a journal of the American Heart Association.
Patients with coronary artery disease and extremely low HDL (“good”) cholesterol were given a combination of the cholesterol-lowering agents simvastatin (Zocor®) and niacin (vitamin B3), this same combination plus antioxidant supplements (beta-carotene, vitamin C, vitamin E and selenium), the antioxidants alone, or a placebo. The simvastatin-niacin group and the simvastatin-niacin plus antioxidants group had similar reductions in total cholesterol, LDL (“bad”) cholesterol, and triglycerides.
The simvastatin-niacin group, however, had greater increases in HDL cholesterol, and greater reductions in a less well-known heart disease risk factor (called lipoprotein A-I) than did those taking the combination of simvastatin-niacin and antioxidants. The authors concluded that the antioxidants blunted the favorable response to simvastatin-niacin. An accompanying editorial called for a halt to recommendations of antioxidants for the prevention and treatment of cardiovascular disease.2 However, when the totality of evidence is considered, the conclusion of that editorial appears unwise.
If antioxidants do blunt one of the effects of simvastatin-niacin therapy, that does not necessarily mean that the net effect of antioxidants is negative. By analogy, supplementation with niacin has been shown to raise blood levels of homocysteine, an effect which would be expected to increase the risk of heart disease.3 Yet, niacin therapy has been shown to reduce heart disease-related mortality.4 Evidently, the beneficial effects of niacin on cholesterol levels and other cardiac risk factors such as fibrinogen outweigh any potential adverse effect on homocysteine levels.5
Antioxidants have numerous positive effects on the cardiovascular system that are unrelated to cholesterol regulation. For example, vitamins E and C each inhibit platelet aggregation and prevent the oxidation of LDL cholesterol, effects which are believed to prevent the development of cardiovascular disease.6 7 8 9 Moreover, there is direct clinical evidence that vitamin E may prevent heart attacks,10 although research in this area is conflicting.11 In addition, there are some apparently beneficial interactions between antioxidants and simvastatin and related drugs. For example, in one study, eight weeks of simvastatin plus vitamin E (300 IU per day) improved markers of blood vessel elasticity more than simvastatin alone.12 In a double-blind trial, lovastatin (a drug similar to simvastatin) was found to increase oxidative damage to LDL cholesterol (which might increase blood vessel damage), but this effect was partially blocked by vitamin E.13
It is important not to draw conclusions about any particular therapy solely on the basis of how that treatment affects individual laboratory values. For example, even though estrogen-replacement therapy lowers serum cholesterol levels in postmenopausal women,14 it does not reduce their risk of heart disease.15 The reported interaction between simvastatin-niacin and antioxidants does not appear to be sufficient reason for people to deprive themselves of the potentially beneficial effects of antioxidant supplements.References