Eating a handful of nuts a day, more legumes and whole grains, and less red and processed meat, could increase life expectancy by more than a decade, according to a major international study (1).

The modelling study, just published in the journal PLoS Medicine, calculated for the first time, the impact of food choices on life expectancy.

Key findings:

The study found that switching from a typical ‘Western’ diet to an ‘Optimal’ diet at 20 years of age could extend life expectancy by 13 years for men and 10.7 years for women.

And eating more legumes, whole grains and nuts, and less red and processed meat would lead to the greatest gains in life expectancy, say the University of Bergen researchers.

Consuming 25g nuts/day from 20 years of age could increase life expectancy by almost two years.

Table 1: Increase in life expectancy from long-term dietary changes made at age 20 years* (1)

*Data from US-based men and women.

According to the research, fruit and vegetables, along with fish, also had important positive impacts, but intake of these foods in a typical diet is closer to dietary targets than it is for legumes, whole grains and nuts.

Australians aren’t eating enough nuts. A secondary analysis of the latest Australian Health Survey data found just 2% of Australians ate 30g nuts a day. Instead, the average (mean) intake was just 4.6g a day (2).

The researchers suggest that health gains are generally linked to reduction in cardiovascular disease, cancer and diabetes mortality.

Globally, dietary risk factors are estimated to cause 11 million deaths annually (3).

Other findings from the study:

The study also found it’s never too late to make dietary changes.

While diet changes earlier in life made the most difference, switching to an ‘optimal’ diet at the age of 60 could still result in an extra eight years of life, and even at 80, could extend life expectancy by more than three years.

And simple dietary tweaks in the right direction, even if not entirely ‘optimal’, can still boost life expectancy.

The researchers termed this a ‘feasibility’ approach – the mid-point between an optimal diet and a typical Western diet – recognising that for some people, this may be more achievable.

For nuts, the ‘Optimal’ diet included 25g/day (the amount in roughly a handful) and the ‘Feasibility’ diet had half that, at 12.5g/day.

Table 2: Changes in life expectancy by switching from a Western diet to an ‘Optimal’ or ‘Feasibility’ diet* (1)

*Data from US-based men and women.

Did you know? A diet low in nuts and seeds has a bigger impact on disease burden than a diet low in vegetables, according to data from the Australian Institute of Health and Welfare (AIHW) (4).

Table 3: Make-up of the ‘Optimal’ diet used in the modelling study (1)

An in-depth research review, which combined the findings of 20 good-quality studies, found that people who ate 28g (a handful) of nuts a day had a 22% reduced risk of dying early, compared with people who almost never ate nuts (5).

The bottom line:

This first-of-its-kind modelling study offers tangible data on how different dietary patterns, and the food groups within these, impact life expectancy.

It found eating more legumes, whole grains and nuts, and less red and processed meat, could increase life expectancy by more than a decade – underlining the power of small, do-able dietary ‘tweaks’ that can be sustained over time.

And a good place to start is by adding a handful of nuts to your day, every day!