Aims/hypothesis
Mice that are deficient for complement factor 3 (C3) have shown resistance to weight gain, despite increased food intake.
Cross-sectional studies of humans have reported correlations between C3 and obesity. This longitudinal study explored whether
C3 predicts a large weight gain in middle-aged men.
Methods
Plasma concentrations of C3 and complement factor 4 (C4) were measured in 2,706 non-diabetic healthy men aged between 38 and
50 years, who were re-examined after a mean period of 6.1 years.
Results
After adjustments for initial weight, age, height and follow-up time, the odds of incurring large weight gain (75th percentile,
≥3.8 kg) were 1.00 (reference), 0.96 (95% CI:0.7–1.2), 1.1 (CI:0.9–1.5) and 1.4 (CI:1.1–1.8), respectively, among men with
C3 levels in the first, second, third and fourth quartiles (p for trend=0.01) respectively. This relationship remained significant after further adjustments for lifestyle factors (physical
inactivity, alcohol, smoking), metabolic factors (glucose or homeostasis model assessment values, cholesterol, triglycerides),
inflammatory markers (fibrinogen, haptoglobin, ceruloplasmin, orosomucoid, α1-antitrypsin) and for C4. C4 was associated with
weight gain after adjustments for initial weight, height, follow-up time and lifestyle factors, but not after adjustments
for C3.