Healthy lifestyle behaviors and decreased risk of mortality in a large prospective study of U.S. women and men

Adiposity, insufficient physical activity, cigarette smoking, and poor diet have all been related independently to increased chronic disease risk, but their joint impact on overall health remains unclear. In a cohort of 170,672 women and men aged 51-71 years at baseline in 1996/1997 and followed-up through 2009, we investigated the individual and joint impact of four low-risk lifestyle factors: abdominal leanness (waist circumference < 88 cm in women and < 102 cm in men); recommended physical activity level (30 min or more of moderate exercise at least 5 times per week or 20 min or more of vigorous exercise at least 3 times per week); long-term non-smoking (never-smoker or quit smoking more than 10 years ago); and healthy diet (Mediterranean diet score within the upper two sex-specific quintiles). During 2,126,089 person-years of follow-up, 20,903 participants died. In multivariate Cox models, statistically significant decreased risks of mortality were observed for the low-risk factors abdominal leanness (relative risk (RR) = 0.86; 95 % confidence interval (CI) = 0.83-0.89), physical activity (RR = 0.86; 95 % CI = 0.84-0.89), non-smoking (RR = 0.43; 95 % CI = 0.42-0.45), and healthy diet (RR = 0.86; 95 % CI = 0.83-0.88). The larger the number of low-risk lifestyle factors, the lower was the mortality risk. The RR comparing adherence to all versus none of the factors was 0.27 (95 % CI = 0.25-0.29). We estimate that 33 % (95 % CI = 30-35 %) of deaths in our cohort were premature and could have been avoided if all study participants had adhered to all low-risk factors.