We know we should eat better to live longer. Why are so few of us doing it?

If asked to guess the makings of a healthy diet – one to help us enjoy healthier, longer lives – most of us would be able to make a pretty good approximation of it.

Which is why the findings of a large new study, published this week in Nature Medicine, tracking the dietary patterns of more than 100,000 US adults over 30 years to determine the best diet for healthy ageing, weren’t too surprising.

What you eat today walks and talks tomorrow: Most people know what a healthy meal looks like.Credit: iStock

Higher intake of fruits, vegetables, whole grains, unsaturated fats, nuts, legumes and low-fat dairy products was linked to greater odds of healthy ageing, while a diet high in trans fats, sodium, sugary beverages and red and/or processed meats was associated with a lower likelihood of healthy ageing.

Researchers examined long-term adherence to eight healthy dietary patterns and healthy ageing over 30 years.

Yet only 9.3 per cent of participants experienced healthy ageing, which researchers measured by cognitive, mental and physical health, as well as living up to 70 years free from chronic disease.

All diets were positively associated with healthy ageing, but the diet with the strongest correlation was the Alternative Healthy Eating Index (a diet developed by some of the same authors of the paper), which includes recommendations of five servings a day of vegetables, and an extra serving of green leafy vegetables, a serving a day of plant protein (such as nuts or legumes) and a serving of fish weekly.

Globally, diet is one of the highest behavioural risk factors for death and chronic disease. Changing what we eat, then, is a simple way to increase longevity and stave off illness.

Dr Anne-Julie Tessier, an assistant professor in the Department of Nutrition at the University of Montreal, and a visiting scientist at Harvard, co-authored the study.

She says the findings have important implications for shaping public health policies.

“Traditionally, dietary guidelines have focused on preventing chronic diseases like heart disease. Our study highlights the potential for dietary recommendations to consider not only disease prevention but also promoting healthy ageing as a long-term goal.”

Aussie diets on the decline

Despite a growing wellness industry worth $US1.3 trillion ($2.07 trillion) and long-term growth in Australian spending on health, dietary habits aren’t necessarily changing for the better.

New research from the CSIRO, published earlier this month, predicted Australian diets would worsen by 2030, with the intake of discretionary foods (ultra-processed foods and sugary drinks) to rise 18 per cent and the intake of fruit to decline 10 per cent. Vegetable intake remained steady, but was far below recommended levels.

Using predictive modelling techniques, researchers analysed nine years of self-reported data from more than 275,000 Australians to forecast dietary trends and compare them with national guidelines.

Their findings suggest drastic change is needed if we are to meet these targets in five years.

Australia’s National Preventive Health Strategy outlines ambitious nutrition targets to reach by 2030: Two servings of fruit a day, five servings of vegetables a day, and reducing discretionary foods to less than 20 per cent of total energy intake.

“It was concerning to see that Australian diet quality is declining, but we’re hoping that this could be an early warning system to help get us back on track,” says Dr Gilly Hendrie, a research scientist who co-authored the CSIRO study.

Interestingly, young adults (18 to 30) were the only age group to show an increase in vegetable consumption, though their intake of discretionary foods remained high.

Start young, and focus on prevention

So, what needs to change?

Professor Luigi Fontana, scientific director of the University of Sydney’s Charles Perkins Centre, whose team has been working with schools in NSW, says education is key.

More than this, he says young people need to be taught the mechanisms behind healthy lifestyle choices.

“It’s not enough to tell them, ‘Eat more fruits and vegetables and don’t drink soda or [eat] processed food’.”

“This topic is as important as math, as English, as chemistry,” he says.

“Unless students understand how different types of physical activity modulate some of these ageing and metabolic pathways, how different nutritional interventions change the risk of developing different diseases [for example], nothing will change.”

He thinks education programs should also give people the skills to put this new knowledge into action.

“Most people, even if they know that legumes are important, have no idea how to cook them; how to put together something that is healthy and tasty,” he says.

Fontana says more education also needs to go hand-in-hand with changes to our primary healthcare system to focus on prevention rather than managing chronic disease.

Accessibility is another important factor, Hendrie says.

“The availability and price of fresh produce around the country will make it easier for people to eat well at a community level, making it easier and the norm to have healthy lunchboxes for kids at school or healthy snacks at sport on the weekend,” she says.

It’s never too late

No matter your age, it’s never too late to make changes and reverse some of the damage caused by a poor diet.

Experts say gradual changes are more likely to lead to lasting change. A large study from 2017 with participants mostly over the age of 60 found simple changes could result in at least an 8 per cent reduction in mortality during the study period and a 7 to 15 per cent drop in their likelihood of dying from heart disease

Hendrie suggests trying to “double the amount of fruit and veg that we eat, and halve the amount of discretionary food”.

Tessier says a diet geared towards healthy ageing needn’t be prohibitively costly.

“Frozen or canned fruits and vegetables can provide comparable health benefits to fresh produce, often at a lower cost and with a longer shelf life.″

Trying to eat better for ageing? Here are some recipes from Good Food to get you started

• These simple fibre-rich recipes will give the whole family a health kick
• Chickpea, brown rice and greens salad with creamy harissa dressing
• Lentil and tuna salad with honey Dijon dressing
• Satay tempeh rice bowls with crunchy kimchi cucumbers
• 14 recipes that’ll make you actually want to eat more veg this week

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