The combined effects of diet and lifestyle on healthy longevity

Healthy longevity is influenced not only by diet but also various lifestyle factors, including smoking, physical activity, alcohol consumption, and body weight. Given the interconnected nature of these factors, it is useful to examine the combined effects of diet and lifestyle factors on longevity. Using data from NHS and HPFS [152], we defined five low-risk lifestyle factors as fulfilling either: never smoking, maintaining normal weight (BMI 18.5–24.9 kg/m2), 30+ minutes/day moderate to vigorous physical activity, moderate alcohol intake (no more than one drink per day for women and no more than two for men), and a high-quality diet as indicated by the AHEI in the upper 40%. The multivariable-adjusted HRs for mortality in adults with five low-risk factors compared with those with none were 0.26 (95% CI: 0.22–0.31) for all-cause mortality, 0.35 (95% CI: 0.27–0.45) for cancer mortality, and 0.18 (95% CI: 0.12–0.26) for CVD mortality. We estimated that the life expectancy at age 50 was 29.0 years (95% CI: 28.3–29.8) for females and 25.5 years (95% CI: 24.7–26.2) for males who adopted zero low-risk lifestyle factors and 43.1 years (95% CI: 41.3–44.9) for females and 37.6 years (95% CI: 35.8–39.4) for males who adopted five low-risk lifestyle factors (Fig. 4). Consequently, adhering to all five low-risk factors could potentially prolong life expectancy at age 50 by 14.0 years for females and 12.2 years for males, in comparison to those adopting none.

In further analyses, adherence to the low-risk lifestyle was associated with a longer life expectancy at age 50 free of major chronic diseases (cancer, CVD, and diabetes) of approximately 7.6 years in men and 10 years in women compared with participants with no low-risk lifestyle factors [153]. These findings suggest that most of the extended life expectancies resulting from a healthy diet and lifestyle are free from major chronic diseases. In other words, following a healthy diet and lifestyle not only enhances overall life span but also extends health span, contributing to a longer period of disease-free life expectancy. Adherence to these lifestyle factors was also strongly associated with lower risk of frailty in older women [154].

Summary and public health implications

This review provides an overview of dietary factors related to longevity and healthy aging, primarily based on findings from large cohort studies. First, maintaining a healthy weight across various life stages is crucial for achieving longevity and healthy aging. This approach—reminiscent of the “80% full” principle found in the traditional Okinawan diet—mimics the positive effects of lifelong, moderate calorie restriction, especially within today’s obesogenic food environment.

Second, the specific food sources or types of dietary fat, protein, and carbohydrates appear to be more important in influencing the risk of chronic diseases and mortality than their quantity. The debate on the superiority of low-fat versus low-carbohydrate diets is not meaningful unless the food sources of fats or carbohydrates are clearly defined. For example, the specific food sources of macronutrients can alter the relationship between carbohydrate intake and mortality risk. A low-carbohydrate diet dominated by animal-derived fat or protein was associated with higher mortality, but a low-carbohydrate diet rich in plant-based fat and protein was associated with lower mortality.

Third, although there is no one-size-fits-all diet for everyone, some traditional diets such as the MedDiet, Nordic, and Asian and contemporary dietary patterns such as HEI-2015, the AHEI, and the DASH diet share many common components while embracing distinct elements from diverse cultures. These dietary patterns typically emphasize minimally processed plant foods and healthy fats, coupled with reduced consumption of red and processed meats and added sugars. The existence of multiple healthy eating patterns across diverse cultures offers the flexibility of combining beneficial elements of various dietary patterns to create personalized diets that enhance long-term enjoyment and adherence.

Fourth, a healthy diet often includes a variety of plant foods rich in polyphenols and other phytonutrients with antioxidant and anti-inflammatory properties. Higher consumption of polyphenols has been associated with beneficial effects on the gut microbiome [155] and small-molecule metabolites [156], contributing to better physical and mental health. Polyphenol-rich foods drawn from diverse cultures and regions of the world, such as coffee, tea, a variety of fruits and vegetables, cocoa, EVOO, avocados, nuts, and seeds, can be tailored to fit individuals’ own food preferences and cultures.

Fifth, adopting a healthy diet along with other lifestyle factors (not smoking, engaging in regular physical activity, maintaining a healthy weight, and consuming alcohol in moderation [if any]) can potentially add approximately 8 to 10 years of disease-free life expectancy. Beyond physical health and longevity, a healthy diet and lifestyle can help to promote mental well-being and mitigate age-related cognitive decline, reducing the risk of dementia and enhancing the overall quality of life.

Lastly, healthy dietary patterns’ emphasis on plant-based foods and sustainable practices aligns with concerns about the environmental impact of the global food system. They are widely recognized to not only reduce risk of chronic diseases and mortality but also contribute to lower greenhouse gas emissions, resulting in lower environmental impact [157, 158].

These findings hold important clinical and public health implications. Health professionals should encourage and support individuals to maintain a healthy weight and prevent excess weight gain across all life stages. Balancing dietary choices and physical activity levels, coupled with regular weight monitoring, are practical strategies in countering age-related weight gain. For older adults, it is critical to address concerns related to sarcopenia and unintentional weight loss and frailty due to chronic conditions through appropriate dietary strategies including maintaining adequate protein intake and taking vitamin or mineral supplements when necessary. Recent RCTs have suggested that daily multivitamin supplements moderately improved memory and other cognitive functions in older adults [159, 160], though further confirmation of these findings is needed. Moreover, clinicians should promote a holistic approach to healthy aging by emphasizing not only dietary habits but also other lifestyle factors, including regular exercise, avoidance of smoking and excess alcohol drinking, ensuring sufficient sleep, and fostering meaningful social connections.

From the public health point of view, policies and initiatives should aim to create a healthier food environment where nutritious options are not only accessible but also the default [161]. This extends to homes, health care facilities, and nursing care facilities for older adults. Public health measures, such as soda taxes, front-of-package labeling, and restricting unhealthy food marketing, can shift societal norms and guide individuals toward healthier eating behaviors. In addition, public health strategies must address the pervasive consumption of ultra-processed foods of low nutritional value, which have been linked to increased obesity and chronic diseases [162, 163]. Reducing consumption of these foods not only improves physical health but also positively impacts mental well-being. Finally, by focusing on both human health and planetary health, public health strategies should encourage the adoption of healthy plant-based foods while minimizing the environmental footprint of dietary choices [164, 165]. This requires incorporating environmental sustainability into dietary guidelines for healthy aging as well as broader agricultural and food policies.

Future research directions

Given that the majority of studies on diet and healthy aging have been conducted in US and European populations, there is an urgent need to conduct long-term cohort studies in diverse populations with varied cultural traditions and eating patterns. Even though the diets from the Blue Zones are considered models for healthy aging, more rigorous investigations are required to better understand nutritional profiles and the health consequences of these diets. To achieve this goal, it is vital to develop better dietary assessment tools that are suitable for culturally diverse populations. Although traditional self-reported instruments, such as food frequency questionnaires, 24-h recalls, and food records, will likely remain as the mainstay for large-scale population-based studies, it is crucial to develop objective biomarkers to improve the assessment of various dietary patterns and their components. Although high-throughput metabolomics have shown promise in identifying biomarkers of specific food intakes and dietary patterns, it is imperative to validate these biomarkers across diverse populations [166, 167].

Recognizing that various eating patterns have overlapping components but also unique features, it is useful to conduct intervention studies to test the effects of combining multiple beneficial elements of different eating patterns on health outcomes. A recent 18-month RCT conducted in Israel demonstrated that compared to a control diet, a diet rich in polyphenols achieved by integrating the components of MedDiet with walnuts, green tea, and Mankai (a specific duckweed strain) shake led to a significant reduction in visceral adiposity [168] and age-related brain atrophy [169]. This “fusion diet” approach not only amplifies the benefits of dietary strategies to reduce chronic diseases and promote healthy aging but also enhances acceptability by broader populations.

There is an increasing need to identify reliable biomarkers that reflect the effects of diet on healthy aging outcomes. Such biomarkers can provide insights into mechanisms by which diet influences aging and offer potential end points for assessing the efficacy of dietary interventions. Although epigenetic clocks and telomere lengths are emerging as promising biomarkers for aging research, their broad applications in clinical settings require further research and validation [170, 171]. This underscores the need for a deeper understanding of the biological mechanisms underlying diet and healthy aging. Emerging evidence suggests that certain dietary patterns, such as the MedDiet and its components, could influence multiple molecular pathways related to healthy aging [172]. These include reduction of chronic inflammation and oxidative stress, decreased rates of telomere shortening and epigenetic aging, amelioration of mitochondrial dysfunction, maintenance of protein homeostasis, and regulation of nutrient-sensing pathways. Given our limited understanding of these mechanisms, more in-depth mechanistic studies and human trials are needed to better elucidate the molecular pathways, which can help develop biomarkers that better characterize the effects of diet on the aging process.