A new 30-year study of eight popular diets has identified the one most likely to keep you healthiest into your 70s and beyond.
The Alternative Healthy Eating Index (AHEI) diet was found to offer slightly greater health benefits than the Planetary Health Diet Index, Mediterranean diet, healthful plant-based diet and others.
The AHEI diet prioritises higher intakes of vegetables, fruits, legumes and nuts. Some meat, fish and dairy are allowed, but other foods are limited, including sugar-sweetened drinks, red and processed meats, salt and trans fats.
Other diets included in the study were similar, but differently weighted in terms of how much meat was allowed, for instance, or emphasis on specific foods such as olive oil, fish or berries.
“This diet contains all the nutrients and different types of food that a person needs to live healthily,” co-corresponding author Dr Marta Guasch-Ferré, associate professor at the University of Copenhagen, told BBC Science Focus. “It is one of the most used dietary patterns in nutrition and was developed to prevent chronic disease.”
In this study, nutrition scientists at Harvard T.H. Chan School of Public Health, the University of Copenhagen and the University of Montreal analysed data from more than 105,000 middle-aged nurses and health professionals.
Over the course of 30 years, the participants completed dietary questionnaires, which the scientists scored based on how similar they were to eight different dietary patterns.
Only 9,771 participants – 9.3 per cent of the study population – were judged as having aged healthily, but those who ate diets most similar to the AHEI were found to be 86 per cent more likely to reach the age of 70 in good health.
These people were also more than twice as likely to reach the age of 75 in good health compared to those whose diets least resembled the AHEI.
Healthy ageing was defined as reaching the age of 70 without major chronic diseases – such as heart disease, diabetes, cancers and so on – and with good cognitive, physical and mental health.
“This study is on healthy ageing – because it’s not only about living longer, but being able to live longer with better health,” said Guasch-Ferré. “We are focusing not only on lifespan, but health span.
“Everyone wants to live longer, but also stay independent in physical function, cognition, and emotional and mental state. I think that’s why this research is important.”
The second-best performing diet was the Planetary Health Diet Index, which considers human and environmental health by prioritising plant-based eating.
However, closer adherence to any of the eight diets was associated with better ageing. Each of them emphasised a higher intake of plant-foods, including vegetables, wholegrains, nuts and legumes, over meat.
But they were each slightly different. Some were versions of the Mediterranean diet, believed to promote longevity, while others were more strictly plant-based, and the rest were developed for specific purposes, such as reducing inflammation or protecting against cognitive decline.
Guasch-Ferré said it was interesting that the diet most closely associated with healthy ageing was one that included low to moderate amounts of healthy animal-based foods.
She said these proteins might be helpful for midlife and older populations – for instance, to protect against osteoporosis – but may not be ideal for younger adults, who were not included in this study.
A lower intake of ultra-processed foods – industrially manufactured foods that contain artificial ingredients – was also associated with better ageing. This study was published in Nature Medicine.
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About our expert:
Dr Marta Guasch-Ferré is an associate professor at the Department of Public Health at the University of Copenhagen, Denmark. She also holds a position as adjunct associate professor at the Department of Nutrition at Harvard T.H. Chan School of Public Health. She holds a PhD in Nutritional Epidemiology.
