Context Human adipose tissue expresses and releases the proinflammatory cyt
okine interleukin 6, potentially inducing low-grade systemic inflammation i
n persons with excess body fat.
Objective To test whether overweight and obesity are associated with low-gr
ade systemic inflammation as measured by serum C-reactive protein (CRP) lev
el.
Design and Setting The Third National Health and Nutrition Examination Surv
ey, representative of the US population from 1988 to 1994,
Participants A total of 16 616 men and nonpregnant women aged 17 years or o
lder
Main Outcome Measures Elevated CRP level of 0.22 mg/dL or more and a more s
tringent clinically raised CRP level of more than 1.00 mg/dL.
Results Elevated CRP levels and clinically raised CRP levels were present i
n 27.6% and 6.7% of the population, respectively. Both overweight (body mas
s index [BMI], 25-29.9 kg/m(2)) and obese (BMI, greater than or equal to 30
kg/m(2)) persons were more likely to have elevated CRP levels than their n
ormal-weight counterparts (BMI, <25 kg/m(2)). After adjustment for potentia
l confounders, including smoking and health status, the odds ratio (OR) for
elevated CRP was 2.13 (95% confidence interval [CI], 1.56-2.91) for obese
men and 6.21 (95% CI, 4.94-7.81) for obese women. In addition, BMI was asso
ciated with clinically raised CRP levels in women, with an OR of 4.76 (95%
CI, 3.42-6.61) for obese women. Waist-to-hip ratio was positively associate
d with both elevated and clinically raised CRP levels, independent of BMI.
Restricting the analyses to young adults (aged 17-39 years) and excluding s
mokers, persons with inflammatory disease, cardiovascular disease, or diabe
tes mellitus and estrogen users did not change the main findings.
Conclusion Higher BMI is associated with higher CRP concentrations, even am
ong young adults aged 17 to 39 years. These findings suggest a state of low
-grade systemic inflammation in overweight and obese persons.