Background
While much is known about correlates of C-reactive protein (CRP), little is known about correlates of other inflammation biomarkers. As these measures are increasingly being used in epidemiologic studies, it is important to determine what factors affect inflammation biomarker concentrations.
Methods
Using age, sex and body mass index (BMI) adjusted linear regression, we examined 38 exposures (demographic and anthropometric measures, chronic disease history, NSAIDs, dietary factors, supplement use) of 8 inflammation biomarkers [CRP, interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor-alpha (TNF-α), and soluble TNF receptors (sTNFR) in plasma; and prostaglandin E2 –metabolite (PGE-M) in urine] in 217 adults, aged 50-76 years.
Results
Increasing age was associated with higher concentrations of all biomarkers except IL-1β. BMI was positively associated with CRP and sTNFR I and II. Saturated fat intake was associated with increased CRP, sTNFRII, TNF-α, and IL-1β, while EPA+DHA intake (diet or total) was associated with decreased CRP, TNF-α, and IL-1β. Results for sex were varied: CRP and IL-6 were lower among men, whereas PGE-M and sTNFRI were higher. Higher CRP was also associated with smoking, HRT use, and γ-tocopherol intake; lower CRP with physical activity, and intakes of dietary vitamin C and total fiber.
Conclusions
Although the associations varied by biomarker, the factors having the greatest number of significant associations (p<=0.05) with the inflammation biomarkers were age, BMI, dietary saturated fat and EPA+DHA omega 3 fatty acids.
Impact
Our results suggest that potential confounders in epidemiologic studies assessing associations with inflammation biomarkers vary across specific biomarkers.