The study, published Monday in Nature Food, was based on a model used to estimate how lifestyle changes could affect a person's life expectancy, and used data on 467,354 participants from the UK Biobank, a large-scale biomedical database and research resource containing genetic and health information on half a million UK participants.
The model found that people in their 40s who switched their unhealthy diet to a longevity-associated diet could add around 10 years to their life expectancy. The change was associated with an extra 10.8 years for women and 10.4 years for men.
Going from eating an average diet, rather than an explicitly unhealthy one, to the longevity-associated diet was meanwhile linked to a life expectancy gain of 3.1 years for women in their 40s, increasing slightly to 3.4 years for men. Making the same dietary changes in their 70s was associated with a life expectancy gain of around five years.
But overall, they found that the bigger the changes towards a healthy diet, the bigger the expected gains in life expectancy were.
Two Important Facts:
Whole grains, nuts, and fruit were associated with the biggest life expectancy gains.
Those that were most closely linked to mortality were sugar-sweetened beverages and processed meat.
According to the researchers' analysis, a longevity-associated diet consisted of a high intake of milk and dairy, vegetables, nuts, and legumes, and a moderate intake of whole grains, fruit, fish, and white meat.
This has parallels with the Mediterranean diet, which is widely considered one of the healthiest ways to eat and emphasizes whole grains, lean proteins, fruits and vegetables, and healthy fats, while limiting processed foods, as well as sugary and fried foods.
The unhealthy dietary pattern, which was most closely associated with dying sooner, contained no or limited amounts of whole grains, vegetables, fruits, nuts, legumes, fish, milk and dairy, and white meat and substantial amounts of processed meat, eggs, refined grains, and sugar-sweetened beverages.