A cross-sectional study published in the American Journal of Epidemiology (August 15, 2009; 170(4):464–471) examined vitamin C status and disease risk markers in 979 nonsmoking men and women aged 20 to 29 who were participating in the Toronto Nutrigenomics and Health Study. Fasting morning blood samples were used to measure serum ascorbic acid (vitamin C), and dietary intake was assessed over one month using a 196-item food frequency questionnaire. The researchers found that 14% of participants were vitamin C deficient and an additional 33% had suboptimal levels. Lower serum vitamin C was associated with higher levels of C-reactive protein (CRP), a marker of inflammation that is also used to assess cardiovascular risk.
CRP is a globular protein that rises in response to tissue injury or inflammation and has been shown to be a strong predictor of cardiovascular disease. Research published in the Journal of the American Nutraceutical Association (2005; 8(1):43–44), involving more than 27,000 women, reported that CRP was a better predictor of cardiovascular disease than LDL (“bad”) cholesterol. Elevated CRP levels have also been linked with increased all-cause mortality. A study published in Clinical Chemistry (February 2008; 54(2):335–342) found that CRP levels greater than 3 mg/L nearly doubled the risk of death in men, increased the risk of heart attack by a factor of 2.15, and raised cancer risk by a factor of 1.6.
In the Toronto study, participants with vitamin C deficiency also tended to have higher waist circumference, higher body mass index, and higher blood pressure compared with those who had adequate vitamin C levels. Dietary intake appeared to play a role, as approximately one in seven participants failed to meet the recommended daily intake for vitamin C.
