Serum Carotenoids and Markers of Inflammation in Nonsmokers

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Abstract
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 × 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.