Comparing the risk of cardiovascular diseases and all-cause mortality in four lifestyles with a combination of high/low physical activity and healthy/unhealthy diet: a prospective cohort study

BACKGROUND: In this study, we assessed the risk of cardiovascular diseases (CVDs) and all-cause mortality in subjects having an only physical activity or a healthy diet or both compared to those having none of these healthy behaviors in the Golestan Cohort Study (GCS). METHODS: A total of 50,045 participants aged ≥ 40 years were recruited from Golestan Province, Iran, from 2004 to 2008 and followed for a median of 13.9 years. Four lifestyles were compared: healthy diet and active (HDA), healthy diet but inactive (HDI), unhealthy diet but active (UDA), and unhealthy diet and inactive (UDI), with UDI being considered as the reference group. Diet quality was assessed by the Dietary Approaches to Stop Hypertension diet score, which was calculated based on a validated food frequency questionnaire. The primary outcomes were death from any cause and CVDs. Adjusted Cox models were used to estimate the hazards ratio (HR) and 95% confidence intervals (CI) for overall and CVDs mortality. RESULTS: During 467,401 person-years of follow-up, 6,256 overall deaths and 2,043 confirmed CVDs deaths were reported. After adjustment for potential confounders, there was a significant lower risk for all-cause mortality in participants with both healthy behaviors (HR = 0.79, 95% CI = 0.73 to 0.86) or only one healthy behavior [HDI: HR = 0.84, 95% CI = 0.78 to 0.90)] and [UDI: HR = 0.91, 95% CI = 0.85 to 0.97] compared to those with both unhealthy behaviors. For CVDs mortality, the HDA lifestyle (HR = 0.74, 95%CI = 0.65 to 0.86), as well as the UDA lifestyle (HR = 0.83, 95%CI = 0.74 to 0.94) indicated a significant lower risk compared to the UDI lifestyle. The HDI lifestyle was not more effective than UDI. CONCLUSION: The greatest reduction in all-cause and CVDs mortality was related to the HDA. For all-cause mortality, both HDI and UDA lifestyles were associated with a decreased risk in comparison to UDI, but for CVDs mortality, only UDA but not HDI decreased the risk. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12966-022-01374-1.