An epidemiological perspective on diet strategies for promoting healthy aging and longevity

Abstract

In recent decades, global life expectancies have risen significantly, accompanied by a marked increase in chronic diseases and population aging. This narrative review aims to summarize recent findings on the dietary factors influencing chronic diseases and longevity, primarily from large cohort studies. First, maintaining a healthy weight throughout life is pivotal for healthy aging and longevity, mirroring the benefits of lifelong, moderate calorie restriction in today’s obesogenic food environment. Second, the specific types or food sources of dietary fat, protein, and carbohydrates are more important in influencing chronic disease risk and mortality than their quantity. Third, some traditional diets (e.g., the Mediterranean, Nordic, and Okinawa) and contemporary dietary patterns, such as healthy plant-based diet index, the DASH (dietary approaches to stop hypertension) diet, and alternate healthy eating index, have been associated with lower mortality and healthy longevity. These patterns share many common components (e.g., a predominance of nutrient-rich plant foods; limited red and processed meats; culinary herbs and spices prevalent in global cuisines) while embracing distinct elements from different cultures. Fourth, combining a healthy diet with other lifestyle factors could extend disease-free life expectancies by 8–10 years. While adhering to core principles of healthy diets, it is crucial to adapt dietary recommendations to individual preferences and cultures as well as nutritional needs of aging populations. Public health strategies should aim to create a healthier food environment where nutritious options are readily accessible, especially in public institutions and care facilities for the elderly. Although further mechanistic studies and human trials are needed to better understand molecular effects of diet on aging, there is a pressing need to establish and maintain long-term cohorts studying diet and aging in culturally diverse populations.

Introduction

In recent decades, life expectancy around the world has shown a remarkable increase, due to reduction in infant mortality and improvements in health care, nutrition, and public health measures [1]. However, longer life expectancies, along with declining birth rates, have led to a greater proportion of elderly individuals in many populations. In the meantime, there has been a rapid increase in the prevalence of chronic diseases, including diabetes, cardiovascular diseases (CVDs), cancer, dementia, and other age-related conditions [2]. Many of these diseases are related to suboptimal diet and lifestyles. Indeed, poor diet is recognized as a leading contributor to the global burden of diseases, including deaths and disability-adjusted life years (DALYs); it was estimated that worldwide, 11 million premature deaths and 255 million DALYs per year were attributable to unhealthy dietary factors including high sodium and trans fat, and low fruits, vegetables, nuts, and omega-3 fatty acids [3].

The concept of “healthy longevity” has garnered much attention in recent years because it is focused on not only increasing the overall life expectancy or life span of individuals but also on increasing the length of life free from major chronic diseases, often referred to as the “healthspan” [4]. The National Academy of Medicine defined healthy longevity as “years of good health approach the biological life span, with physical, cognitive, and social functioning that enable well-being” [5]. The definition underscores a preventive approach to health and well-being through diet and lifestyle modifications. This concept is also closely linked to healthy aging, which refers to maintenance of physical, mental, and cognitive health as individuals grow older [6], while preventing or delaying the onset of frailty in elderly individuals [7].

This narrative review aims to summarize recent findings on the dietary factors influencing chronic diseases and longevity, primarily from large cohort studies. Specifically, we highlight findings from two large cohort studies: the Nurses’ Health Study (NHS) and Health Professionals’ Follow-up Study (HPFS), which are among the largest and longest running cohort studies on diet and health in the world [8-10]. Besides large sample sizes, a long duration of follow-up spanning more than three decades, and high rates of follow-up (>90%), detailed data on diet and lifestyle factors have been collected every 2–4 years. The repeated measures of diet are particularly useful in reducing measurement errors stemming from self-reported diets and representing long-term dietary habits [9]. Because large randomized clinical trials (RCTs) of diet and longevity are typically not feasible due to lack of long-term adherence and cost considerations, observational data derived from high-quality cohorts—combined with insights from small RCTs in humans and experimental data from animal studies—can substantially enhance our understanding of the role of diet in preventing chronic diseases and reducing premature deaths, which can help to formulate evidence-based nutritional strategies to support healthy longevity in aging populations [11].