The team from Norway undertook a modelling study using meta-analysis and databases from the established Global Burden of Disease 2019 dataset which associates various dietary components with mortality mainly as a result of cardiovascular disease (CVD), diabetes and cancer.
Using these datasets, the team investigated the impact on life expectancy if individuals were to shift from ‘Typical Western’ (TW) eating habits to:
- An optimised sustainable diet (OD) such as that recommended by EAT Lancet diet and daily food quantities set at levels beyond which no further benefits would be gained OR
- A feasible approach (FA) option: half-way shift between current eating habits and the optimised diet
|Whole grains||50 g||137.5 g||225 g||e.g., 2 thin slices of rye bread and 1 small bowl of whole grain cereal and some whole grain rice). For whole grains 225 g of fresh weight corresponds to about 75 g dry weight equivalent of 7 servings/day);|
|Vegetables||250 g||325 g||400 g||5 servings e.g., 1 big tomato 1 sweet pepper mixed salad leaves a half avocado and a small bowl of vegetable soup);|
|Fruits||200 g||300 g||400 g||5 servings e.g. 1 apple banana orange kiwi and a handful of berries);|
|Nuts||0 g||12.5 g||25 g||1 handful of nuts|
|Legumes||0 g||100 g||200 g||e.g., 1 big cup of soaked beans/lentils/peas|
|Fish||50 g||125 g||200 g||e.g., 1 big slice of herring|
|Eggs||50 g||37.5 g||25 g||Half an egg|
|Milk/dairy||300 g||250 g||200 g||e.g., 1 cup of yoghurt|
|Refined grains||150 g||100 g||50 g||e.g., refined grains in bread if mixed whole/refined bread|
|Red meat||100 g||50 g||0 g|
|Processed meat||50 g||25 g||0 g|
|White meat||75 g||62.5 g||50 g|
|Sugar-sweetened beverages||500 g||250 g||0 g|
|Added plant oils||25 g||25 g||25 g|
TW = Typical Western Diet – a combination of US, China and European databases
FA = Feasibility Approach: halfway between TW and optimised diet
OD = optimized diet – e.g., EAT Lancet with food quantities set at levels beyond which no further health benefit could be gained (according to meta-analysis data)
Prolonged life years could be gained by a sustained change to either the OD or the FA. The latter providing (on average) half the expected gains compared to the OD but still significantly improving life expectancy compared to continuing on the current TW diet.
The full impact results are achieved after the improved dietary habits are adopted for a period of 10 years. However, based on meta-analysis data, increases to life expectancy would start from 2 years of adoption and gradually increase year by year to plateau at 10-years.
Improved life expectancy across all age ranges
Starting young would result in the biggest benefits. A 20-year-old male shifting to OD pattern would expect to increase life expectancy by 13 years and a woman by 10 years, whilst shifting to OD at 60 years would result in an 8.8-year and 8-year gain for men and women respectively. Even making the shift at 80 years could prolong life by 3.4 years for men and women.
More beans, nuts and whole grains and less red and processed meat hold the key to prolonged life!
When assessing the individual food components for optimum impact on life expectancy, there were some clear winners:
- Consuming more beans (200g daily), whole grains (5 servings daily) and a handful of nuts daily
- Avoiding red and processed meat was clear that legumes, whole grains
It’s important to note that even achieving the FA quantities i.e., not avoiding but instead halving current red and processed meat intakes and consuming beans, whole grains and nuts daily but at half the quantities of the OD would still produce significant results.
Shifting to a plant-based sustainable diet will significantly prolong life expectancy, mainly through improved CVD, diabetes and cancer outcomes. The earlier in life population groups make the transition the better the outcomes, however, all age groups can benefit and reduce their disease burden by adopting healthier diets now. The fact that even part transition to the optimum diet can produce significant improvements should be used as a motivating factor for those finding the dietary shift a challenge. The optimum diet is clearly far removed from current eating habits, so it may be beneficial to focus on introducing the dietary changes in a step-by-step manner and starting with the foods likely to produce the biggest impact i.e., more beans, whole grains and nuts and reducing red and processed meat.