Impact of C-reactive protein on disease risk and its relation to dietary factors.

C-reactive protein (CRP) is one of the acute-phase proteins in inflammation and CRP serum concentrations are therefore of interest. Data for high-sensitivity CRP (hs-CRP) with a low detection limit of approximately 0.04 mg/L have become available over the past decade and research has shown a link between high concentrations of hs-CRP and obesity as well as smoking. Expanded adipose tissue is in fact known to secrete proinflammatory cytokines which enhance hepatic synthesis of CRP. Moderate alcohol consumption and high physical activity have been associated with low levels of hs-CRP, but the evidence in these cases is not conclusive. It has been suggested that hs-CRP is an independent marker of the risk of cardiovascular disease, but the predictive capacity remains controversial. However, many prospective studies have observed increased risk of type 2 diabetes mellitus associated with high concentrations of hs-CRP, independent of obesity and other cardiovascular risk factors. On the other hand, no measurable increase in the risk associated with high levels of hs-CRP was observed with multivariate adjustment in several studies. A number of authors have reported that high concentrations of hs-CRP are associated with increased risks of colorectal and other cancers, but the findings again are inconsistent. Diet and hs-CRP are also of increasing research interest. High intakes of carotenoids and vitamin C, but not of vitamin E, seem to decrease the level of circulating hs-CRP. In addition, high consumption of vegetables and fruit are associated with lower levels of circulating hs-CRP, perhaps by exerting anti-inflammatory effects. Both mechanistic and epidemiologic studies regarding dietary factors and low-grade inflammation are necessary to add to our knowledge of dietary influence on chronic disease development.