Dietary intakes of fruits and vegetables and lung cancer risk in participants with different smoking status: a meta-analysis of prospective cohort studies.

ABSTRACT

BACKGROUND AND OBJECTIVES: The results from epidemiological studies are controversial between vegetable and fruit consumption and lung cancer risk in participants with different smoking status. The present meta-analysis aimed to investigate these associations with prospective cohort studies. Meanwhile, the potential dose-response relationship was evaluated. METHODS AND STUDY DESIGN: Relevant studies were identified with PubMed and Scopus databases up to June 2019. Multivariate-adjusted relative risks for the highest versus the lowest category and 95% confidence intervals were calculated by using a random-effects model. The dose-response relationship was examined by using restricted cubic spline regression model. RESULTS: Eight prospective studies were included for data synthesis. The summary estimates indicated that higher vegetable and fruit intake was significantly associated with lower risk of lung cancer in participants with current smokers (RR 0.84, 95% CI 0.73, 0.95; I2=25.2%). No significant association was found in former smokers (RR 0.97, 95% CI 0.88, 1.07; I2=15.0%) and never smokers (RR 0.90, 95% CI 0.74, 1.11; I2=6.6%). Dose-response analysis showed that 100 g/day increment of vegetable and fruit intake was associated with a 2% reduction in lung cancer risk among current smokers (95% CI 0.97, 0.99). CONCLUSIONS: The present meta-analysis provides significant evidence of an inverse association between vegetable and fruit intake and lung cancer risk in current smokers.