It’s well established that diet quality is a leading predictor of chronic disease risk and all-cause mortality, in particular, death from cardiovascular disease.
A poor diet increases the likelihood of developing key risk factors, including hypertension, high cholesterol, elevated blood sugar and obesity.
Now, research published in the July issue of the American Journal of Clinical Nutrition has projected that adopting a “longevity-optimized” diet could extend life expectancy by as many as 10 years.
Here’s a breakdown of the study, plus which foods – and how much – to eat to potentially help you live longer.
About the new diet-longevity study
For the study, an international research team estimated gains in life expectancy that would result from making sustained changes from a typical national eating pattern, such as a Western or Nordic diet, to a “longevity-optimized” diet.
The study’s researchers also predicted increases in life expectancy that would occur from moving from a typical national diet pattern to a more “feasible diet change,” defined as being halfway between a typical Western diet and a “longevity-optimized” diet pattern.
Life expectancy is the number of years an individual at a certain age is expected to live based on age-specific death rates.
Countries included in the study were the United States, United Kingdom, France, Germany, Norway, China and Iran.
Statistics from those countries were used to determine the intake of 15 different food groups by adults. These included whole grains, fruits, vegetables, nuts, legumes (beans, lentils, peas), fish, eggs, dairy, refined grains, red meat, processed meat, white meat, sugar-sweetened beverages, added sugars and added oils.
Data from high-quality meta-analyses were used to establish the association between the consumption of various food groups and all-cause mortality. (A meta-analysis combines data from many studies.)
Hallmark foods in a “longevity-optimized” diet
The optimal diet includes, per day, seven whole grain servings (a serving is equivalent to one-half cup of cooked grain or one slice of bread), five vegetable servings (a serving is equivalent to one-half cup of cooked vegetables or one cup of salad greens) and five fruit servings (a serving is equivalent to one whole fruit or one-half cup of berries).
Each day it also has a small handful of nuts, one cup of beans, lentils or peas, six ounces of fish, half an egg and two ounces of white meat.
The optimal diet is very low in refined grains and contains no red or processed meat, sugar-sweetened beverages or added sugars.
The findings
Among 40-year-old males and females, the estimated gains in life expectancy moving from a typical diet pattern to a “longevity-optimized” diet ranged from 6.2 years in China to 9.5 years in the United States.
Adopting the optimal diet at age 60 was also projected to increase life expectancy. In the United States and the United Kingdom, for example, transitioning from a typical Western diet added seven years of life.
Even making moderate diet changes had longevity benefits. In the United States, adopting the “feasible” diet at age 40 was predicted to increase life expectancy by five years. Doing so at the age of 60 added 3.5 years of life for females and 3.9 for males.
The largest gains in life expectancy from making a sustained dietary change were projected in the United States, with the second largest in the United Kingdom.
Overall, eating more legumes, whole grains, and nuts, and eating less red and processed meats and sugar-sweetened beverages, were estimated to result in the biggest increases in life expectancy.
In the United States, the three most impactful dietary changes were increasing whole grains and legumes while reducing sugar-sweetened beverages.
Limitations, strengths
The researchers’ estimates did not consider past illness or other risk factors such as genetic susceptibility or advancements in medical treatments, all of which can impact life expectancy.
To their credit, the researchers built their model using comprehensive meta-analyses. They also were able to consider the time between making dietary change to achieving its full longevity effect (that is when sustained dietary change doesn’t increase life expectancy further).
The researchers stated that “even with the most conservative approaches, the predicted gains in life expectancy from eating healthier are substantial.”
Shifting to a longevity-focused diet
While the typical Canadian diet wasn’t included in the study, the findings are still useful since most Canadians eat a typical American/Western diet.
To improve the quality of your diet, start by making “feasible” changes.
That means, according to the study, adding one vegetable serving, one fruit serving, 3.5 whole grain servings, half a handful of nuts, one-half cup of legumes and 2.5 ounces of fish to your daily diet.
It also means eating fewer refined grains and cutting the intake of red and processed meat, sugary drinks and added sugars by one-half.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD