A healthy diet has long been associated with living into old age – and you don’t have to follow it perfectly to reap the benefits
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Five dietary patterns have been associated with living years longer, regardless of someone’s genetic risk factors for disease, in a study of more than 100,000 people.
“If you want to live a long life, it’s definitely worth trying to have a healthier eating pattern, and the good news is that it doesn’t have to be absolutely perfect,” says Clare Collins of the University of Newcastle in Australia, who was not involved in the study.
Yanling Lv of Huazhong University of Science and Technology in China and her colleagues looked at the link between diet and longevity by analyzing data from 103,000 participants in the UK Biobank Study. The subjects were scored based on how closely they reported following five previously validated healthy diets: a Mediterranean diet, a plant-based diet, the DASH (Dietary Approaches to Stop Hypertension) diet, the DRRD (Diabetes Risk Reduction Diet) and the AHEI (Alternative Healthy Eating Index).
These five diets vary slightly in their approach, but in general, “they all recommend high intake and a wide variety of vegetables and fruits, they all recommend whole grain intake, they all recommend lean protein sources, and many of these are vegetarian proteins,” says Collins. They also recommend steering clear of sugary drinks and ultra-processed food.
The study’s subjects were followed for a decade, during which time around 4,300 of them died. Lv and her colleagues found that participants whose dietary habits closely matched one or more of the five healthy dietary patterns were less likely to have died, even after adjusting for factors such as exercise level and smoking status.
Based on the data, the researchers calculated that a 45-year-old in the top fifth of healthy eaters – meaning they have close adherence to any of the five healthy diets – can expect to live one and a half to three years longer than someone in the bottom fifth.
Importantly, the fifth healthiest eaters in the study tended to have good dietary results, but not perfect. “This is positive because it shows that you don’t have to be an absolute goody-two-shoes all the time to benefit from it,” says Collins.
The study also found that people with genetic variants linked to reduced longevity were still less likely to die if they ate well, showing that “even if you don’t have big longevity genes, diet can make a big difference in mortality risk,” says Collins.
The reason these five diets are associated with longer life is probably because they all involve eating large amounts and diversity of plants, which contain fiber, vitamins, minerals and phytonutrients, says Collins.
Fiber improves immune function because metabolism in the gut releases anti-inflammatory short-chain fatty acids. Vitamins and minerals are necessary to carry out basic body functions, while phytonutrients are additional bioactive substances in plants that can improve these functions. “Phytonutrients play an active role in things like improving insulin sensitivity and anti-cancer pathways,” says Collins.
In the study, Lv and her colleagues found that high fiber intake had the strongest connection with increased longevity, and a high intake of sugar-sweetened beverages had the least. Excessive sugar consumption can lead to the development of type 2 diabetes and other metabolic conditions, thereby reducing life expectancy, they write.
A weakness of the study was that the dietary score was based on the participants’ recollection of what they had eaten in the last 24 hours on only two separate days, says Luigi Fontana at the University of Sydney in Australia. “A multi-day food diary can better approximate long-term patterns,” he says.
Another limitation was that it was an observational study, rather than an intervention study, says Fontana. In other words, it didn’t actively put people on healthy diets and see if that made them live longer. But the findings are nevertheless consistent with other studies that have linked these five diets to a lower risk of disease and a longer life, he says.
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