Fruit and vegetable intake and smoking cessation

In cohort studies, fruit and vegetable (F&V) intake is associated with lower cardiovascular diseases (CVDs). Former smokers often have a higher F&V intake than current smokers. If a high intake of F&V precedes smoking cessation, the latter may explain the favorable association between F&V intake and CVD among smokers. The objective was to assess whether higher F&V intake precedes smoking cessation.

The study population comprised 1056 male smokers from Lille (France) and Belfast (Northern Ireland) aged 50-59 years on inclusion in 1991. At baseline, participants completed self-administered questionnaires related to smoking habits, demographic, socioeconomic factors and diet. At the 10-year follow-up, smoking habits were assessed by mailed questionnaire.

After 10 years, 590 out of 1056 smokers had quit smoking (70.7% of smoker in Lille and 37.8% in Belfast). After adjusting for center, consumption of F&V was associated with quitting (odds ratio (OR) for high versus low F&V intake: 1.73; 95% confidence interval (CI): (1.22-2.45); P-trend=0.002). After further adjustment for sociodemographic factors, body mass index and medical diet, the association was still statistically significant (OR: 1.59; 95% CI (1.12-2.27); P-trend = 0.01). In a model fully adjusted for age, smoking intensity, alcohol consumption and physical activity, the association was no longer significant (P = 0.14).

Higher F&V intake precedes smoking cessation. Hence, smoking cessation could affect the causal interpretation of the association between F&V and CVD in smokers.