A new study led by researchers at the University of California, Berkeley, adds to the evidence that vitamin C supplements can lower concentrations of C-reactive protein (CRP), a central biomarker of inflammation that has been shown to be a powerful predictor of heart disease and diabetes.
The same study found no benefit from daily doses of vitamin E, another antioxidant.
The study led by Gladys Block, UC Berkeley professor emeritus of epidemiology and public health nutrition.
“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,” said 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.”
The researchers said that for people with elevated CRP levels, the amount of CRP reduction achieved by taking vitamin C supplements in this study is comparable to that in many other studies of cholesterol-lowering drugs called statins. They noted that several larger statin trials lowered CRP levels by about 0.2 milligrams per liter; in this latest study, vitamin C lowered CRP by 0.25 milligrams per liter.
“This finding of an effect of vitamin C is important because it shows in a carefully conducted randomized, controlled trial that for people with moderately elevated levels of inflammation, vitamin C may be able to reduce CRP as much as statins have done in other studies,” said Block.
Evidence of the link between elevated CRP levels and a greater risk of heart disease has grown in recent years, but it had been unclear whether the beneficial effects of lowering CRP were independent of the effects of lowering cholesterol.
Although this study ended at two months, Block noted that there is no evidence to date of adverse effects for longer-term use of vitamin C at high levels. At the same time, researchers acknowledged the need to study whether vitamin C’s beneficial impact on CRP levels continue past two months.
The National Institutes of Health helped support this research.
Source: University of California, Berkeley, USA