Body fat percentage is more strongly associated with biomarkers of low-grade inflammation than traditional cardiometabolic risk factors in healthy young adults - the Lifestyle, Biomarkers, and Atherosclerosis study.

The primary aim was to appraise the relationship between body fat percentage and the inflammatory markers C-reactive protein (CRP) and orosomucoid in a population of young, non-smoking, healthy, Swedish adults, without any chronic diseases. A secondary aim was to compare whether these associations differed between the women using estrogen contraceptives and those who did not. We assessed the association in linear regression models between body fat percentage based on a bio-impedance measurement and plasma concentrations of CRP and orosomucoid in men and women aged 18-26 years, n = 834. Statistically significant associations were found between body fat percentage and both biomarkers of inflammation, with β coefficients of 0.30 (95% CI 0.24-0.37) and 0.28 (0.22-0.35) for CRP and orosomucoid, respectively (p < .001). Adjustment for established risk factors marginally lowered the effects sizes (partial betas, 0.28 and 0.20, respectively), while the strong statistically significant associations remained. In the female cohort, estrogen and non-estrogen using subpopulations did not significantly differ in the correlations between body fat percentage and the inflammatory biomarkers, even adjusted for established cardiometabolic risk factors. In conclusion, in healthy young adults, higher levels of body fat percentage are associated with elevations in plasma biomarkers of inflammation, suggesting that a systemic inflammatory process, promoting atherosclerosis, may commence already at this early stage in life. CRP and orosomucoid plasma concentrations differed between users and non-users of estrogen contraceptives, but both subgroups showed similar correlations between increasing body fat percentage and increasing plasma concentrations of the biomarkers of inflammation.