Posted on 17 February 2022
Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.
Why is this research important: We know that diet is important for health and lifespan, but how important? The world of nutrition can be confusing to navigate even for researchers, with thousands of nutrition related scientific articles published every year. Any research that can improve our understanding of the impact of different food groups on life expectancy is welcome.
What did the researchers do: In this study, researchers used data from previous meta-analyses on diet and health, data from the Global Burden of Disease study (a global study analysing the relationships between a wide range of risk factors and mortality), and a life table method in order to estimate how life expectancy would change according to dietary changes. A life table, in its simplest form, is a table that calculates the probability of a person still being alive after a given period of time has passed.
The researchers estimated what an optimal diet for longevity would be. The main characteristics of the optimal diet were significantly higher intake of whole grains, legumes, fish, fruits, vegetables when compared to a western diet, and a reduced intake of red and processed meats, sugar-sweetened beverages and refined grains. The researchers also devised a ‘feasibility approach diet’ as a more achievable compromise between the optimal diet and the typical western diet.
Key takeaway(s) from this research: The researchers estimated that a person who switched from the western diet to the optimal diet at age 20 and maintained this change throughout life would increase their life expectancy by over a decade. A woman in the United States would gain 10.7 years life expectancy, while a man would gain 13 (estimates for countries in Europe and Asia were similar).
The life expectancy benefits of the different dietary changes broke down as follows: eating more legumes (females: 2.2; males: 2.5), whole grains (females: 2.0; males: 2.3), and nuts (females: 1.7; males: 2.0), less red meat (females: 1.6; males: 1.9) and processed meat (females: 1.6; males: 1.9).
They estimated that if this dietary adjustment was made instead at age 60, life expectancy might still be increased by 8-9 years, while 80 year-olds would gain 3.4 years.
If the feasibility approach diet was adopted at age 20, researchers estimated a 6.2 year life expectancy increase for women and a 7.3 year increase for men.
A portion of this effect is probably due to a reduction in calorie intake associated with dietary change. It’s also worth remembering that these estimates are based on data that is mostly observational in nature, and though meta analyses will attempt to control for as many confounding factors as possible, these will still exert an influence on the estimates presented here.
Estimating impact of food choices on life expectancy: A modeling study: https://doi.org/10.1371/journal.pmed.1003889