Diet and Healthy Aging: What We Can Learn From Long-Term Research

Most of us hope to grow old feeling physically and mentally well. Diet is often regarded as one of the key pillars for getting there. What counts as a healthy diet, though, has many interpretations today and often depends on who you ask and in what context.

In this article, I explore that question through a recent long-term study that examined how different dietary patterns relate to healthy aging. Rather than focusing on individual diseases or nutrients, this research asks how eating habits over decades may be linked to a more integrated picture of aging well — one that includes physical, cognitive, and mental functioning.

A 30-year look at diet and healthy aging

Diet is among the leading risk factors for disease and mortality in the United States. At the same time, it is one of the factors that many people can change.

To understand how diet might shape healthy aging, a Nature Medicine study analyzed data from two large, long-running cohort studies. These studies tracked diet, lifestyle, and health outcomes among health professionals between 1986 and 2016. Together, the analysis included more than 105,000 participants and up to 30 years of follow-up.

The researchers wanted to know which long-term eating patterns tend to go hand in hand with aging in good health.

How do researchers measure diet over decades?

In studies like this one, researchers usually rely on self-reported food questionnaires. About every four years, participants reported how often they had eaten a wide range (over 130) of foods over the previous year.

Researchers then grouped these foods into several dietary patterns, such as the Alternative Healthy Eating Index, the Mediterranean diet, and various plant-based diet scores. These aren’t strict diets, but scoring systems designed to capture overall diet quality and eating habits over time.

These scores focus on slightly different goals or health outcomes. For example, the Dietary Approaches to Stop Hypertension (DASH) score places more emphasis on factors important for heart health, while the Mediterranean diet score gives more weight to foods such as olive oil, nuts, and fish. Even so, they overlap to a large extent. Overall, these scores reflect what we usually mean by a healthy diet: more vegetables, fruits, grains, and healthy fats, and fewer processed foods, red meats, and trans fats.

What is considered 'healthy aging' in research?

Aging research often distinguishes between lifespan and healthspan, pointing out that living to an older age isn’t the same as reaching that age in good health. The meaning of ‘good health’ in this context has also evolved over time.

In line with recent thinking from the World Health Organization, this study defined healthy aging as more than being free of serious disease. Participants were considered healthy agers if they reached at least age 70 and met all of the following criteria:

1. Had not been diagnosed with major chronic diseases such as heart disease, cancer, or type 2 diabetes
2. Reported no cognitive decline
3. Reported no significant mental health problems, mainly depressive symptoms
4. Maintained physical function, could manage everyday tasks such as climbing stairs or doing housework without major difficulty

That’s a high bar for a 70-year-old. In fact, fewer than one in 10 participants (9.3%) met all of these criteria. This all-or-nothing definition doesn’t necessarily reflect how aging usually looks in real life. Instead, it helps researchers identify factors linked to the best possible outcomes.

This is also what makes the study distinctive. Many studies look at diet in relation to single diseases or outcomes. Far fewer take this more integrated view of aging as something that unfolds across multiple dimensions at once.

What the researchers found

The researchers examined eight different dietary patterns. Higher long-term adherence to any of them was associated with greater odds of healthy aging.

The strongest association was seen with the Alternative Healthy Eating Index (AHEI). Participants with the highest adherence had about 86% higher odds of healthy aging compared with those in the lowest group.

Broadly speaking, the AHEI reflects how well someone follows current dietary guidelines. Like most of the patterns examined, it emphasizes fruits, vegetables, whole grains, and other plant-rich foods, while limiting red and processed meats, trans fats, sugary drinks, and ultra-processed foods.

In other words, these dietary patterns were nothing particularly exotic — just consistently choosing more of what we already consider ‘healthy’ foods, and less of what we don’t.

Foods associated with healthier (and less healthy) aging

Similar patterns came up when researchers looked at individual foods and nutrients. Better odds of healthy aging were associated with higher intake of:

1. Fruits and vegetables
2. Whole grains
3. Nuts
4. Legumes
5. Unsaturated fats
6. Low-fat dairy

Lower odds were associated with diets higher in:

1. Trans fats
2. Sodium
3. Sugary drinks
4. Red and/or processed meats

Consistency may matter

While many of us hear that 'consistency is key' almost too often, this near-cliché earns its mention here, too. Participants who maintained higher-quality diets through midlife had the greatest likelihood of healthy aging.

A few limitations to keep in mind

As large and comprehensive as this study is, it still has limitations worth keeping in mind.

Self-reported data

Diet, as well as cognitive, physical, and mental health, was assessed using self-reported questionnaires. These tools are validated and practical for long-term research, but they’re not immune to imperfect recall or reporting bias.

Who was studied

The participants were health professionals who may differ from the general population in education, health awareness, and access to care. That means the results may not fully generalize to everyone.

Alcohol

Some readers may notice that both the AHEI and Mediterranean diet scores include alcohol. Historically, moderate drinking was thought to be beneficial for health. While the evidence — and with it, our understanding — is shifting toward the view that likely no amount of alcohol is safe, official guidelines are still catching up. As a result, moderate alcohol intake remains part of these scoring systems.

Correlation, not causation

Like most long-term nutrition research, this study is observational. It shows that healthier diets are associated with healthier aging, but it can’t tell which comes first. Eating well may support better aging, but it’s also possible that people who age more healthily are better able to maintain healthier diets for other reasons.

The researchers adjusted for many relevant factors, such as smoking, physical activity, socioeconomic status, and other lifestyle variables. Still, some degree of confounding is unavoidable.

Bottom line

The takeaway of the 30-year study isn’t revolutionary. If anything, it reinforces advice we’ve heard many times before: eat more fruits, vegetables, whole grains, and healthy fats, and limit sugary drinks, ultra-processed foods, and red and processed meats.

There’s also a useful reminder here: taking care of how well our bodies and minds function in old age doesn’t start in old age. It starts much earlier, often decades earlier.

Still, healthy aging isn’t only about preventing disease, but about maintaining physical, mental, and psychological well-being. After all, diet is just one pillar among many. What we eat matters, but so does how we move, connect with others, and take care of our mental health.