An article scheduled to appear in the January 1, 2009 issue of Free Radical Biology and Medicine reports the finding of researchers at the University of California, Berkeley that supplementing with vitamin C reduces C-reactive protein (CRP), a marker of inflammation linked with an increased risk of cardiovascular disease and diabetes.
Berkeley professor emeritus of epidemiology and public health nutrition Gladys Block and her associates randomized 396 nonsmokers to receive 1000 milligrams vitamin C, 800 international units vitamin E, or a placebo for two months. Serum C-reactive protein levels were measured before and after the treatment period.
Although no effects for vitamin E were observable, and no effect for vitamin C was noted among those with desirable CRP levels, for participants with elevated C-reactive protein (defined as 1 milligram per liter or higher), vitamin C lowered CRP by 0.25 milligrams per liter compared to the placebo, a reduction similar to that associated with statin drug treatment.
"This is an important distinction; treatment with vitamin C is ineffective in persons whose levels of CRP are less than 1 milligram per liter, but very effective for those with higher levels," stated Dr Block. "Grouping people with elevated CRP levels with those who have lower levels can mask the effects of vitamin C. Common sense suggests, and our study confirms, that biomarkers are only likely to be reduced if they are not already low."
Dr Block noted that a trial reported earlier this week in the Journal of the American Medical Association, which found no association between supplementation with vitamins C and E and the risk of stroke or heart attack, failed to screen participants for CRP elevation, which is important in the determination of who might benefit from vitamin C.
In another recently reported study ( the Jupiter trial), Harvard Medical School researchers showed that statin drugs reduced cardiovascular disease and cardiovascular mortality in individuals with normal lipids and elevated CRP. The trial found a 37 percent reduction in CRP associated with statins compared to treatment with a placebo. "One of the strengths of the Jupiter trial is that only persons with CRP levels greater than 2 milligrams per liter were enrolled," Dr Block remarked. "Researchers found very important effects of lowering CRP in people who had high levels to begin with."
"Major studies have found that the level of CRP in the body predicts future risk of cardiovascular disease, including myocardial infarction, stroke and peripheral artery disease, as well as diabetes," Dr Block stated. "Some believe CRP to be as important a predictor of future heart problems as high levels of LDL and low levels of HDL cholesterol."
"This is clearly a line of research worth pursuing," she added. "It has recently been suggested by some researchers that people with elevated CRP should be put on statins as a preventive measure. For people who have elevated CRP but not elevated LDL cholesterol, our data suggest that vitamin C should be investigated as an alternative to statins, or as something to be used to delay the time when statin use becomes necessary."