Serum carotenoids and markers of inflammation in nonsmokers

One explanation for discrepant results between epidemiologic studies and ra ndomized trials of beta -carotene and cardiovascular disease may be a failu re to consider inflammation as a confounder. To evaluate the potential for such confounding, the authors relate the serum concentrations of five carot enoids (alpha -carotene, beta -carotene, beta -cryptoxanthin, lycopene, and lutein/zeaxanthin) to levels of three inflammatory markers (C-reactive pro tein, fibrinogen, and white blood cell count) measured during the Third Nat ional Health and Nutrition Survey, 1988-1994. The analysis included 4,557 n onsmoking participants aged 25-55 years. Adjusted concentrations of all fiv e carotenoids were significantly lower in those with C-reactive protein lev els above 0.88 mg/dl (p = 0.001). There was a trend toward lower adjusted b eta -cryptoxanthin concentrations with increasing level of fibrinogen (p va lue test for trend = 0.01), but other carotenoids were not related. Many of the carotenoid concentrations were lower among participants with high whit e blood cell counts. After log transformation, only adjusted mean beta -car otene levers were significantly lower in those with white blood cell counts above 7.85 x 10(9)/liter (p < 0.01). These cross-sectional data do not cla rify the biologic relation between carotenoids and C-reactive protein but, to the extent that the carotenoids are associated with C-reactive protein l evels, a carotenoid-heart disease association may be, in part, an inflammat ion-heart disease association.