Relationship of serum cholesterol levels to atopy in the US population

P>Background: Cholesterol promotes Th2 immunity and allergic inflammation in rodents; whether this occurs in humans is unclear. Reports of both direct and inverse associations between serum cholesterol and atopy in different populations suggest that race and/or other demographic variables may modify these relationships. Aims of the study: To determine the relationships between levels of three serum cholesterol measures [total cholesterol (TC), high density lipoprotein-cholesterol (HDL-C), and non-HDL-C] and atopy in a sample representative of the US population. Methods: Cross-sectional study of 6854 participants aged >= 6 years from the 2005-2006 National Health and Nutrition Examination Survey. Results: In the overall population, adjusted odds ratios (AORs) per two-standard deviation increase in TC and non-HDL-C for biochemical atopy (defined as >= 1 allergen-specific IgE to 19 allergens) were 1.17 [95% confidence interval (CI), 1.00-1.38] and 1.19 (95% CI, 1.03-1.39), respectively. Interactions by race were noted for the two relationships (interaction P = 0.004 and P = 0.009, respectively) with non-Hispanic Whites (NHWs) having direct relationships [TC: AOR 1.27 (95% CI, 1.03-1.57); non-HDL-C: AOR 1.27 (95% CI, 1.03-1.56)] and non-Hispanic Blacks (NHBs) inverse relationships [TC: AOR 0.77 (95% CI, 0.62-0.95); non-HDL-C: AOR 0.86 (95% CI, 0.69-1.08)]. The adjusted HDL-C-atopy relationship was nonsignificant for NHWs and inverse for NHBs [AOR 0.77 (95% CI, 0.61-0.96)]. Relationships were independent of body mass index and serum C-reactive protein and unmodified by corticosteroid or statin usage. Results were similar using current hay fever/allergy as the atopy outcome. Conclusions: There are marked inter-racial differences in the relationship between serum cholesterol and atopy in the US population.