Objective To examine how a healthy lifestyle is related to life expectancy that is free from major chronic diseases. Design Prospective cohort study. Setting and participants The Nurses’ Health Study (1980-2014; n=73 196) and the Health Professionals Follow-Up Study (1986-2014; n=38 366). Main exposures Five low risk lifestyle factors: never smoking, body mass index 18.5-24.9, moderate to vigorous physical activity (≥30 minutes/day), moderate alcohol intake (women: 5-15 g/day; men 5-30 g/day), and a higher diet quality score (upper 40%). Main outcome Life expectancy free of diabetes, cardiovascular diseases, and cancer. Results The life expectancy free of diabetes, cardiovascular diseases, and cancer at age 50 was 23.7 years (95% confidence interval 22.6 to 24.7) for women who adopted no low risk lifestyle factors, in contrast to 34.4 years (33.1 to 35.5) for women who adopted four or five low risk factors. At age 50, the life expectancy free of any of these chronic diseases was 23.5 (22.3 to 24.7) years among men who adopted no low risk lifestyle factors and 31.1 (29.5 to 32.5) years in men who adopted four or five low risk lifestyle factors. For current male smokers who smoked heavily (≥15 cigarettes/day) or obese men and women (body mass index ≥30), their disease-free life expectancies accounted for the lowest proportion (≤75%) of total life expectancy at age 50. Conclusion Adherence to a healthy lifestyle at mid-life is associated with a longer life expectancy free of major chronic diseases.

Plant-based dietary patterns, which emphasize foods derived from plant sources and include lower consumption of or exclusion of animal products, have gained significant attention in recent years for their potential to prevent or manage several major chronic diseases, including type 2 diabetes, cardiovascular disease, and cancer.^1-4 Suggested mechanisms for their protective association against the development of type 2 diabetes include higher consumptions of plant foods that are rich in vitamins, minerals, and antioxidants and lower consumption of red and processed meats.^5-7 Meanwhile, depending on the definition of plant-based dietary patterns (eg, lacto-ovo-vegetarian and vegan), the patterns may also exclude certain animal products that are potentially beneficial for the prevention of cardiometabolic diseases, such as yogurt and fish.^8-10 Moreover, refined grains, starches, and sugars can also be characterized as plant-based, although they are independently associated with a higher risk of type 2 diabetes.^10,11 Hence, the overall effect of plant-based diets on the incidence of type 2 diabetes remains to be well characterized, particularly given the potentially opposing health effects of certain plant-based foods on the risk of type 2 diabetes.¹² A recent meta-analysis¹³ of observational studies suggested that vegetarian dietary patterns are associated with a lower risk of type 2 diabetes, although this study was limited by the inclusion of mostly cross-sectional studies and only 2 prospective studies, both of which were performed among US Seventh Day Adventists.^14,15 Hence, it is difficult to generalize the potential beneficial effects of plant-based dietary patterns to populations of other racial/ethnic groups or countries. In addition, while meta-analyses of clinical trials demonstrated beneficial effects of plant-based or vegan dietary patterns on body weight, glycemic control, and cardiovascular risk factors in patients with type 2 diabetes,^16,17 whether plant-based diets have a role in the primary prevention of type 2 diabetes remains unclear.

Background: Cancer poses a huge disease burden, which could be reduced by adopting healthy lifestyles mainly composed of healthy diet, body weight, physical activity, limited alcohol consumption, and avoidance of smoking. However, no systematic review has summarised the relations of combined lifestyle factors with cancer morbidity and mortality.Methods: EMBASE and PubMed were searched up to April 2019. Cohort studies investigating the association of combined lifestyle factors with risks of incident cancer and cancer mortality were selected. Summary hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using random-effects models. Heterogeneity and publication bias tests were conducted.Results: The HRs (95% CIs) comparing individuals with the healthiest versus the least healthy lifestyles were 0.71 (0.66–0.76; 16 studies with 1.9 million participants) for incident cancer and 0.48 (0.42–0.54; 30 studies with 1.8 million participants) for cancer mortality. Adopting the healthiest lifestyles was also associated with 17 to 58% lower risks of bladder, breast, colon, endometrial, oesophageal, kidney, liver, lung, rectal, and gastric cancer. The relations were largely consistent and significant among participants with different characteristics in the subgroup analyses.Conclusions: Adopting healthy lifestyles is associated with substantial risk reduction in cancer morbidity and mortality, and thus should be given priority for cancer prevention.

Whether weight gain after smoking cessation attenuates the health benefits of quitting is unclear. In three cohort studies involving men and women in the United States, we identified those who had reported quitting smoking and we prospectively assessed changes in smoking status and body weight. We estimated risks of type 2 diabetes, death from cardiovascular disease, and death from any cause among those who had reported quitting smoking, according to weight changes after smoking cessation. The risk of type 2 diabetes was higher among recent quitters (2 to 6 years since smoking cessation) than among current smokers (hazard ratio, 1.22; 95% confidence interval [CI], 1.12 to 1.32). The risk peaked 5 to 7 years after quitting and then gradually decreased. The temporary increase in the risk of type 2 diabetes was directly proportional to weight gain, and the risk was not increased among quitters without weight gain (P6 years since smoking cessation). Similar associations were observed for death from any cause. Smoking cessation that was accompanied by substantial weight gain was associated with an increased short-term risk of type 2 diabetes but did not mitigate the benefits of quitting smoking on reducing cardiovascular and all-cause mortality. (Funded by the National Institutes of Health.)

Importance: The associations of serum folate and vitamin B₁₂ levels with cardiovascular outcomes among patients with type 2 diabetes (T2D) remain unclear.Objective: To investigate the associations of serum folate and vitamin B₁₂ levels with risk of cardiovascular disease (CVD) mortality among individuals with T2D.Design, Setting, and Participants: This prospective cohort study included 8067 patients with T2D who participated in the National Health and Nutrition Examination Survey (NHANES) from 1999 through 2014 and NHANES III (1988-1994). American Diabetes Association criteria were used to define T2D. Data were analyzed between October 1, 2020, and April 1, 2021.Exposures: Serum folate and vitamin B₁₂ levels.Main Outcomes and Measures: Multivariable Cox proportional hazards regression models were used to compute hazard ratios and 95% CIs for the associations of serum folate and vitamin B₁₂ levels with risks of CVD and all-cause mortality. Two multivariable models were constructed. Restricted cubic spline analyses were used to examine the nonlinear association of serum folate levels and vitamin B₁₂ levels with CVD mortality, and nonlinearity was assessed using the likelihood ratio test.Results: This cohort study included data from 7700 participants in the folate analysis (mean [SE] age, 57.8 [0.3] years; 3882 women [weighted, 50.5%]; median serum folate level, 12.1 ng/mL [IQR, 7.1-19.5 ng/mL]) and 4860 participants for the vitamin B₁₂ analysis (mean [SE] age, 57.8 [0.3] years; 2390 men [weighted, 50.7%]; median serum vitamin B₁₂ level, 506.1 pg/mL [IQR, 369.1-703.5 pg/mL]). During 72 031 person-years of follow-up, 799 CVD deaths were documented for the folate analysis, and during 43 855 person-years of follow-up, 467 CVD deaths were reported for the vitamin B₁₂ analysis. Nonlinear associations were observed for serum levels of folate (P = .04 for nonlinearity) and vitamin B₁₂ (P = .04 for nonlinearity) with risk of CVD mortality among patients with T2D. Compared with participants in the second quartile of serum folate levels (7.1-12.1 ng/mL), the hazard ratios for CVD mortality were 1.43 (95% CI, 1.04-1.98) for participants in the lowest serum folate level quartile (<7.1 ng/mL) and 1.03 (95% CI, 0.74-1.44) for participants in the highest quartile (≥19.5 ng/mL). In addition, compared with participants in the second quartile of serum vitamin B₁₂ levels (369.1-506.0 pg/mL), the hazard ratios for CVD mortality were 1.74 (95% CI, 1.20-2.52) for participants in the lowest quartile (<369.1 pg/mL) and 2.32 (95% CI, 1.60-3.35) for participants in the highest quartile (≥703.5 pg/mL). Similar patterns of association were observed for all-cause mortality (nonlinearity: P = .01 for folate and P = .02 for vitamin B₁₂).Conclusions and Relevance: This cohort study found that both low and high serum levels of vitamin B₁₂ as well as low serum levels of folate were significantly associated with higher risk of CVD mortality among individuals with T2D.

Background: Plant-based diets have been associated with lower risk of type 2 diabetes mellitus and cardiovascular disease (CVD) and are recommended for both health and environmental benefits. However, the association between changes in plant-based diet quality and mortality remains unclear. Methods: We investigated the associations between 12-year changes (from 1986 to 1998) in plant-based diet quality assessed by 3 plant-based diet indices (score range, 18–90)—an overall plant-based diet index (PDI), a healthful PDI, and an unhealthful PDI—and subsequent total and cause-specific mortality (1998–2014). Participants were 49 407 women in the Nurses’ Health Study (NHS) and 25 907 men in the Health Professionals Follow-Up Study (HPFS) who were free from CVD and cancer in 1998. Multivariable-adjusted Cox proportional-hazards models were used to estimate hazard ratios (HRs) and 95% CIs. Results: We documented 10 686 deaths including 2046 CVD deaths and 3091 cancer deaths in the NHS over 725 316 person-years of follow-up and 6490 deaths including 1872 CVD deaths and 1772 cancer deaths in the HPFS over 371 322 person-years of follow-up. Compared with participants whose indices remained stable, among those with the greatest increases in diet scores (highest quintile), the pooled multivariable-adjusted HRs for total mortality were 0.95 (95% CI, 0.90–1.00) for PDI, 0.90 (95% CI, 0.85–0.95) for healthful PDI, and 1.12 (95% CI, 1.07–1.18) for unhealthful PDI. Among participants with the greatest decrease (lowest quintile), the multivariable-adjusted HRs were 1.09 (95% CI, 1.04–1.15) for PDI, 1.10 (95% CI, 1.05–1.15) for healthful PDI, and 0.93 (95% CI, 0.88–0.98) for unhealthful PDI. For CVD mortality, the risk associated with a 10-point increase in each PDI was 7% lower (95% CI, 1–12%) for PDI, 9% lower (95% CI, 4–14%) for healthful PDI, and 8% higher (95% CI, 2–14%) for unhealthful PDI. There were no consistent associations between changes in plant-based diet indices and cancer mortality. Conclusions: Improving plant-based diet quality over a 12-year period was associated with a lower risk of total and CVD mortality, whereas increased consumption of an unhealthful plant-based diet was associated with a higher risk of total and CVD mortality.