Body mass and the epidemic of chronic inflammation in early mid-adulthood

Chronic inflammation is a potentially important mechanism through which social inequalities may contribute to health inequalities over the life course. Excess body fat contributes to chronic inflammation, and younger adults in the US have come of age during a pronounced secular increase in body mass index (BMI). We aim to document levels of chronic inflammation in a nationally representative sample of 33-to-44 year-old adults in the US, and to describe associations with BMI, race/ethnicity, and education.

High sensitivity C-reactive protein (CRP) was measured in Wave V (2016-18) of the National Longitudinal Study of Adolescent to Adult Health, with complete data available for 4349 participants. Sex-stratified weighted regression models were implemented to investigate CRP in association with education, race/ethnicity, and BMI.

Geometric mean CRP was 1.9 mg/L, and 35.4% of the sample had CRP >3 mg/L. Females had significantly higher CRP than males. Body mass index was a strong positive predictor of CRP, and education level was negatively associated with CRP. Associations between education and CRP were substantially attenuated after adjusting for BMI. High risk CRP increased linearly with BMI even among the obese: 87.0 percent of females and 74.1 percent of males with class 3 obesity (BMI ≥40) were predicted to have high risk CRP > 3 mg/L.

The obesity epidemic is producing an epidemic of chronic inflammation in early mid-adulthood in the US. Strong associations between BMI and chronic inflammation portend high risk for future disease-and inequitable distribution of disease-as the cohort ages.