Possible protective effect of serum beta-carotene levels on the association between interleukin-1B C-31T polymorphism and hypertension in a Japanese population.

BACKGROUND & AIMS: Recent studies have indicated a close relationship between hypertension and inflammation. Antioxidant substances, including beta-carotene, are known to be preventive factors for hypertension. We investigated the effect of serum beta-carotene levels on the association between the interleukin-1beta (IL-1B) C-31T polymorphism and hypertension.

METHODS

Subjects were 625 inhabitants (200 males and 425 females) of Japan, aged 39-70 years, who attended a health check-up examination in 2003. The IL-1B C-31T polymorphism was genotyped by polymerase chain reaction with confronting two-pair primers. Serum beta-carotene levels were measured using high-performance liquid chromatography.

RESULTS

The TT genotype of IL-1B C-31T was associated with an increased risk of hypertension in all subjects (Odds Ratio [OR]=1.82, 95% Confidence Interval [95% CI]=1.09-3.06, compared with CC genotype). Among male CC carriers, those with high serum beta-carotene levels had a significantly lower OR (OR=0.25, 95% CI=0.06-0.95) for hypertension relative to those with low serum beta-carotene levels. The TT carriers had a significantly higher OR compared with the CC carriers among males with high serum beta-carotene levels (OR=5.03, 95% CI=1.34-21.58) and among females with low serum beta-carotene levels (OR=2.47, 95% CI=1.04-6.00).

CONCLUSION

This study suggests that the IL-1B C-31T polymorphism is associated with hypertension, and that this association is modulated by serum beta-carotene levels.