Objective: The endogenous antioxidant serum bilirubin may scavenge free radicals and protect against free radical-related diseases.
Methods: Using the 10-year follow-up mortality data from the Belgium Inter-university Research on Nutrition and Health (BIRNH) study the association between serum bilirubin and all-cause, cardiovascular, and cancer mortality in 5460 men and 4843 women was investigated.
Results: In men, with the highest (> or = 0.6 mg/dl) compared with the lowest serum bilirubin concentration (< or = 0.2 mg/dl), the adjusted relative risk (RR) was 0.73 (95% confidence interval (CI) 0.57-0.94) for all-cause and 0.42 (95% Cl 0.26-0.68) for cancer mortality. The risk for cancer mortality decreased with increasing concentrations of serum bilirubin (p for trend = 0.004) especially for non-lung cancer mortality (p for trend = 0.02). The associations persisted after adjusting for smoking. In women the associations between serum bilirubin and cancer mortality were in the same direction, but did not reach statistical significance (RR = 0.76, 95% CI 0.39-1.5). No significant associations were found between serum bilirubin and cardiovascular mortality in men and women.
Conclusions: In this population high serum bilirubin, however, within normal ranges, was associated with low cancer mortality, especially in men. This may be due to the antioxidant activity of bilirubin. Measurement of serum bilirubin concentrations may contribute to cancer risk estimation.