A healthy diet has long been linked to living into old age – and you don’t have to adhere to 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 dietary pattern, and the good news is that it doesn’t have to be absolutely perfect,” says Clare Collins at the University of Newcastle in Australia, who wasn’t involved in the study.
Yanling Lv at Huazhong University of Science and Technology in China and her colleagues looked at the association between diet and longevity by analysing data from 103,000 participants in the UK Biobank study. The individuals were scored based on how closely they reported adhering to five previously validated healthy diets: a Mediterranean-type 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’re all recommending high intakes and a big variety of vegetables and fruit, they’re all recommending whole grain intake, they’re all recommending lean sources of protein, and many of those are vegetarian proteins”, says Collins. They also recommend steering away from sugary drinks and ultra-processed foods.
The study’s subjects were followed for a decade, during which time around 4300 of them died. Lv and her colleagues found that the 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 like their exercise levels 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 a year and a half to three years longer than someone in the bottom fifth.
Importantly, the top-fifth healthiest eaters in the study tended to have good dietary scores but not perfect ones. “This is positive because it shows you don’t have to be an absolute goody two-shoes all of the time to benefit,” 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, demonstrating that “even if you haven’t got great longevity genes, diet can make a big difference in terms of mortality risk,” says Collins.
The reason these five diets are associated with longer life is probably that they all involve eating a large amount and diversity of plants, which contain fibre, vitamins, minerals and phytonutrients, says Collins.
Fibre improves immune function because its metabolism in the gut releases anti-inflammatory short-chain fatty acids. Vitamins and minerals are necessary to carry out basic bodily functions, while phytonutrients are extra bioactive substances in plants that can enhance these functions. “Phytonutrients play active roles in things like improving insulin sensitivity and anti-cancer pathways,” says Collins.
In the study, Lv and her colleagues found that high fibre intake had the strongest association with increased longevity, and a high intake of sugar-sweetened beverages had the least. Excess sugar consumption can lead to the development of type 2 diabetes and other metabolic conditions, thereby reducing longevity, they write.
A weakness of the study was that dietary scores were based on the participants’ recollection of what they had eaten in the last 24 hours on just two separate days, says Luigi Fontana at the University of Sydney in Australia. “A multi-day food diary can better approximate longer-term patterns,” he says.
Another limitation was that it was an observational study, rather than an interventional trial, says Fontana. In other words, it didn’t actively put people on healthy diets and see whether it made them live longer. But nevertheless, the findings align with other studies that have linked these five diets to lower disease risks and a longer life, he says.
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