Fruits, vegetables and lung cancer risk: a systematic review and meta-analysis

Abstract

Background: Lung cancer is the most common cause of cancer death. Fruits and vegetables containing carotenoids and other antioxidants have been hypothesized to decrease lung cancer risk. As part of the World Cancer Research Fund International Continuous Update Project, we conducted a systematic review and meta-analysis of prospective studies. Methods:We searched PubMed and several databases up to December 2014 for prospective studies. We conducted meta-analyses comparing the highest and lowest intakes and dose-response meta-analyses to estimate summary relative risks (RRs) and 95% confidence intervals (CIs), and examine possible non-linear associations. We combined results from the Pooling Project with the studies we identified to increase the statistical power of our analysis.Results: When comparing the highest with the lowest intakes, the summary RR estimates were 0.86 [95% CI 0.78-0.94; n (studies) = 18] for fruits and vegetables, 0.92 (95% CI 0.87-0.97; n = 25) for vegetables and 0.82 (95% CI 0.76-0.89; n = 29) for fruits. The association with fruit and vegetable intake was marginally significant in current smokers and inverse but not significant in former or never smokers. Significant inverse dose-response associations were observed for each 100 g/day increase: for fruits and vegetables [RR: 0.96; 95% CI 0.94-0.98, I 2 = 64%, n = 14, N (cases) = 9609], vegetables (RR: 0.94; 95% CI 0.89-0.98, I 2 = 48%, n = 20, N = 12 563) and fruits (RR: 0.92; 95% CI 0.89-0.95, I 2 = 57%, n = 23, N = 14 506). Our results were consistent among the different types of fruits and vegetables. The strength of the association differed across locations. There was evidence of a non-linear relationship (P < 0.01) between fruit and vegetable intake and lung cancer risk showing that no further benefit is obtained when increasing consumption above ∼400 g per day.Conclusions: Eliminating tobacco smoking is the best strategy to prevent lung cancer. Although residual confounding by smoking cannot be ruled out, the current evidence from prospective studies is consistent with a protective role of fruit and vegetables in lung cancer aetiology.

Blood concentrations of carotenoids and retinol and lung cancer risk: an update of the WCRF–AICR systematic review of published prospective studies

“…With the exception of one study that only adjusted for age 31, all the studies included in our analysis were adjusted at least for smoking status, but there was not enough data to conduct subgroup analysis by smoking status. In the only study that showed separate results in smokers and never/former smokers 17, an inverse association with lung cancer mortality was observed for α ‐carotene and β ‐cryptoxanthin only in current smokers but not in never/former smokers, however, in a previous meta‐analysis of fruit and vegetable intakes (some of which are high in carotenoids) and lung cancer risk, we found similar summary RRs among never smokers as compared to current or former smokers 42, although power was more limited among never smokers as the number of cases was modest.…”

Raising Awareness for Lung Cancer Prevention and Healthy Lifestyles in Female Scholars from a Low-Income Area in Bogota, Colombia: Evaluation of a National Framework

“…Furthermore, physical activity levels are also associated with lower lung cancer mortality (low physical activity, hazard ratio (HR) 0.80 (0.69-0.92); medium physical activity, HR 0.68 (0.59-0.80); and high physical activity, HR 0.78 (0.66-0.93)) [9]. Similar evidences have been published regarding fruits and vegetables intake (RR 0.86; 95% CI 0.78-0.94) [10].…”

Diet in lung cancer: back to natural and healthy food

“…Because cigarette smoking accounts for 80% of the worldwide lung cancer burden in men and at least 50% of the burden in women, prevention the onset of smoking and successful smoking cessation strategies in current smokers will be the first effective measure in primary prevention of lung cancer [1,5]. Not smoking is the first strategy in preventing lung cancer [8].…”

“…While high-dose supplements of β-carotene have increased the lung cancer risk in male smokers due to aberrant cell growth in the respiratory epithelium [27], such finding does not exclude that a diet based on fruits, non-starchy vegetables and pulses (legumes), with a high content in vitamins, antioxidants and phytonutrients apart from β-carotene, in more balanced doses, may benefit in reducing lung cancer risk [8]. An illustrative example comes from a systematic review over the cruciferous vegetable (rich in isothiocyanates, like broccoli, cabbage and others) consumption and lung cancer risk conducted by Lam et al [28].…”

“…Tens of case-control and cohort studies conducted over many years in various populations have indicated that people who eat more vegetables and fruits, food rich in β-carotene and carotenoids, and those with higher blood β-carotene concentrations, have a lower risk of lung cancer [32]. A recent meta-analysis from 2016 has concluded that the current evidence from prospective studies is consistent with a protective role of fruits and vegetables in lung cancer etiology [8]. A healthy diet with plenty of whole grains, pulses (legumes), non-starchy vegetables and fruits, with a high content in vitamins, antioxidants and phytonutrients apart from β-carotene, in balanced doses, may benefit in reducing lung cancer risk [8].…”