Serum carotenoids and markers of inflammation in nonsmokers

One explanation for discrepant results between epidemiologic studies and randomized trials of β-carotene and cardiovascular disease may be a failure to consider inflammation as a confounder. To evaluate the potential for such confounding, the authors relate the serum concentrations of five carotenoids (α-carotene, β-carotene, β-cryptoxanthin, lycopene, and lutein/zeaxanthin) to levels of three inflammatory markers (C-reactive protein, fibrinogen, and white blood cell count) measured during the Third National Health and Nutrition Survey, 1988-1994. The analysis included 4,557 nonsmoking participants aged 25-55 years. Adjusted concentrations of all five carotenoids were significantly lower in those with C-reactive protein levels above 0.88 mg/dl (p = 0.001). There was a trend toward lower adjusted β-cryptoxanthin concentrations with increasing level of fibrinogen (p value test for trend = 0.01), but other carotenoids were not related. Many of the carotenoid concentrations were lower among participants with high white blood cell counts. After log transformation, only adjusted mean β-carotene levels were significantly lower in those with white blood cell counts above 7.85 x 10⁹/liter (p < 0.01). These cross-sectional data do not clarify the biologic relation between carotenoids and C-reactive protein but, to the extent that the carotenoids are associated with C-reactive protein levels, a carotenoid-heart disease association may be, in part, an inflammation-heart disease association.