Antioxidants and Cholesterol
Antioxidants and Cholesterol:
Need for a Balanced View of the Evidence
WASHINGTON, D.C.–Last week, the media spread a story on antioxidants that did not fairly reflect the research on which the story was based. The damage to consumer perceptions has been done, but the actual facts still deserve full consideration, and the whole story needs to be put into perspective. The key facts are these:
A recently published study demonstrates that the main effects of cholesterol_lowering drugs are not inhibited by antioxidants. These include lowering total cholesterol, lowering triglycerides, lowering LDL ("bad" cholesterol), and improving the LDL/HDL ratio. Questions are raised about the impact on HDL cholesterol, and especially on one subfraction of HDL.
Vitamin E, vitamin C, and other antioxidants can benefit heart health in ways that are quite separate from the effects of cholesterol_lowering drugs. The new study provides no basis for the antioxidant_bashing that has occurred.
The full story is somewhat complicated. A group of researchers at the University of Washington has been investigating the effects of two cholesterol_lowering treatments (simvastatin and niacin), with and without added antioxidants, as compared to antioxidants alone or a placebo. The antioxidant "cocktail" included in this study consisted of 1000 mg of vitamin C, 800 IU of vitamin E, 25 mg of beta_carotene, and 100 mcg of selenium. The cholesterol_lowering treatments were expected to lower total cholesterol, lower triglycerides, lower LDL cholesterol ("bad" cholesterol), and raise HDL cholesterol ("good" cholesterol).
The simvastatin_niacin treatments did in fact accomplish all these things. When the treatments were given in combination with antioxidants, however, the researchers said the antioxidants "modestly blunted" one of the expected effects, namely the increase in HDL cholesterol. They cautiously refer to this as an "unexpected adverse interaction." The headline of the article assertively announced that antioxidants "block the response of HDL" to the drug treatment. This was the message carried by the media to every corner of the globe, although the data provided in the article do not support this assertion.
The tables in the article show that the primary results of the cholesterol_lowering treatments, with or without antioxidants, were strikingly positive. In both groups, total cholesterol was reduced, triglycerides were lowered, LDL cholesterol was reduced, and HDL cholesterol was increased. The tables show that there was no statistically significant difference between the responses of the two groups, in terms of these effects. These main effects are shown in the table below. The LDL to HDL ratio also was markedly improved in both groups, from a ratio of more than 4 at the beginning of the study to a ratio of about 2 by the end of the study.
STATIN + NIACIN
STATIN + NIACIN
Before After Before After
Total cholesterol 194 141 203 150 *
Triglycerides 195 113 231 170 *
LDL 129 85 131 86 *
HDL 31 41 31 37 *
* No statistically significant difference in response, between the two groups.
When subfractions of HDL were examined by the researchers, total HDL was divided into two fractions __ one fraction accounting for 85% or more of the total and another fraction accounting for 15% or less of the total. The major fraction increased in both groups. The minor fraction increased in the drug group but did not increase in the drug+antioxidant group. The authors are legitimately concerned about the reasons for this difference, and more research is needed. However, there is no consensus on the health significance of changes in the subfractions of HDL, and these subfractions are not the subject of current national cholesterol_lowering guide