If hit podcasts, bestselling books and influencer culture are any indication, millions of people are obsessed with longevity.

But just as important as your life span is your health span, or the number of years you live in good health, said Susan B. Roberts, the senior associate dean for research at the Geisel School of Medicine at Dartmouth in the US.

The length and quality of your life will be determined in part by your genetics, she said. But how you live your life is important, too, including how much you exercise and sleep, whether you drink excessively or smoke — and how you eat, Roberts said.

Eating for longevity isn’t an exact science, of course. It’s unrealistic, and possibly unethical, for researchers to ask people to faithfully follow various diets for decades and then see how their lives turn out, said Dr Frank Hu, a professor of nutrition and epidemiology at the Harvard T.H. Chan School of Public Health in the US. But researchers can look for associations between people’s dietary habits and their long-term health, he said.

Here are the best clues we have for how to eat for a long and healthy life.

Prioritise Protein

Research suggests that those who consume more protein tend to live longer and stay stronger and healthier later in life than those who consume less.

But where you get your protein matters. Plant-based sources such as legumes, nuts and whole grains seem to be especially beneficial, whereas protein from red and processed meat has been linked with shorter lives, Dr Lars Fadnes, a professor of global public health at the University of Bergen in Norway, wrote in an email.

Protein is key to maintaining strong muscles and bones, which can help older adults stay active and avoid falls and fractures, said Denise K. Houston, a professor of gerontology and geriatric medicine at Wake Forest University School of Medicine in the US.

Houston and other experts have recommended that those 65 and older consume 0.45 to 0.54 grams of protein per pound of body weight per day. For a 150-pound (68 kilo) adult, this translates to about 68 to 81 grams of protein. To help your body better absorb and use protein, distribute it across meals throughout the day, Houston said.

Strengthen Bones

In addition to protein, be sure to get enough calcium and Vitamin D to support your bone health as you age, Roberts said.

Dairy milk, as well as fortified plant milks, orange juice and cereals can be good sources of both nutrients. You can also find calcium in yogurt, cheese, tofu, beans and leafy green vegetables. Much of your Vitamin D can come from exposure to sunlight, but foods including fish, mushrooms and eggs provide additional amounts.

It’s best to get calcium from foods if you can, Houston said. But if you’re falling short on either nutrient, talk with your doctor about whether supplements are right for you.

Pump Up Polyphenols

Fruits, vegetables, whole grains and other plant foods like nuts and legumes are rich in polyphenols — antioxidant and anti-inflammatory compounds that some research suggests can support healthy ageing.

Coffee, for example, is a major source of polyphenols. Drinking as much as three to five cups per day has been linked with reduced risks for type 2 diabetes, heart disease, some cancers, Parkinson’s disease, cognitive decline and earlier death, Dr Hu said. Green tea may have similar benefits, he added, though the research is less robust.

Researchers have also linked other polyphenol-rich foods such as berries, dark leafy green vegetables, avocados and extra-virgin olive oil to health benefits, including a longer life and improved brain health.

Choose Healthy Fats

Diets that are high in unsaturated fats — found in olive oil and most other plant oils, nuts, seeds and avocados — have been linked with lower mortality, Dr Hu and his colleagues have found. Alternatively, diets that are rich in saturated fats, which are found in red and processed meats, seem to have the opposite effect.

Fatty fish such as salmon, tuna, anchovies and sardines are rich in omega-3 fatty acids, which are associated with better brain health and a longer life, Houston said.

Avoid Ultraprocessed

This would include foods such as packaged products like hot dogs, chicken nuggets, sodas and many baked goods. Such foods are increasingly linked with greater risks for health conditions including heart disease, type 2 diabetes, dementia and a shortened life span.

Ultraprocessed foods are often high in “fast carbohydrates”, Dr Hu said. These are quickly digested and can lead to blood sugar spikes. Over time, those spikes may increase the risk for type 2 diabetes and cardiovascular disease. Many ultraprocessed foods are also often high in sodium, which can contribute to high blood pressure.

More than any one food, it’s your overall diet that matters, Dr Hu said.

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