Rationale: Although the health effects of beta carotene have been studied extensively, a systematic examination of serum concentrations and long-term mortality, including cardiovascular disease mortality, has not been reported.
Objective: Explore whether serum beta carotene is associated with overall and cause-specific mortality and to elucidate the strength and dose-response of the association.
Methods and results: We conducted a prospective serological analysis of 29 103 men in the ATBC study (Alpha-Tocopherol, Beta-Carotene Cancer Prevention). During 31 years of follow-up, 23 796 deaths occurred, including deaths because of cardiovascular disease (9869), cancer (7692), respiratory disease (2161), diabetes mellitus (119), injuries and accidents (1255), and other causes (2700). Serum beta carotene was assayed using high-performance liquid chromatography. Adjusting for major risk factors measured, men with higher serum beta carotene had significantly lower all-cause mortality (hazard ratios=0.81, 0.71, 0.69, and 0.64 for quintile 2 (Q2)-Q5 versus Q1, respectively; Ptrend<0.0001). Serum beta carotene was significantly associated with risk of death from cardiovascular disease, heart disease, stroke, cancer, respiratory disease, diabetes mellitus, injuries and accidents, and other causes (Q5 versus Q1, hazard ratio=0.21-0.73, all Ptrend<0.0001). The all-cause mortality association was not materially impacted by adjustment for fruit and vegetable consumption (albeit, estimated with some measurement error) and was generally similar across subgroups of smoking intensity, alcohol consumption, trial supplementation, and duration of follow-up, but was significantly modified by age, years of smoking, and body mass index, with stronger inverse associations among men who were younger, smoked fewer years, and had a lower body mass index (all Pinteraction≤0.0025).
Conclusions: This study provides evidence that higher beta carotene biochemical status is associated with lower overall, cardiovascular disease, heart disease, stroke, cancer, and other causes of mortality. The dose-response associations over a 30-year period were not attenuated by adjustment for other important risk factors and support greater fruit and vegetable consumption as a means to increase beta carotene status and promote longevity.
Keywords: beta carotene; cardiovascular diseases; epidemiology; mortality; multivariate analysis; primary prevention.