Article - Estimating impact of food choices on life expectancy: A modeling study.

Plain Language Summary

Dietary choices affect health, however with such a huge amount of research available it is difficult to determine the extent. Models which can estimate the impact of diet on health would be of benefit and this study aimed to use existing research to estimate how different diets affect life expectancy at the population level. The results showed that life expectancy can increase across all ages and genders by changing from a typical Western diet and adopting a sustained healthier one. For example, men aged 20 years from the United States could increase their life expectancy by up to 13 years and 80-year-olds could increase their life expectancy by over 3 years. When changing from a typical Western diet, eating more legumes, whole grains, and nuts, and eating less red and processed meat showed the largest gains in life expectancy. It was concluded that changing from a Western diet to a healthier one can be of benefit to longevity and the biggest benefit is seen if it is adopted early in life. This study could be used by healthcare professionals to understand that healthier diets can extend life expectancy.

Expert Review

Reviewer: Chloe Steele

4th Jul 2024

Conflict of interest

None

Take home message

Sustained dietary changes to one high in fruits, vegetables, whole grains, nuts, legumes, fish, eggs, milk/dairy, and low in red meat, refined grains, processed meat, and sugar-sweetened beverages may be able to increase life expectancy.

Gains in life expectancy can be enhanced by the early adoption and the optimisation of a healthy eating diet.

Evidence category

C: Non-randomized trials, observational studies, narrative reviews

Summary review

Introduction

Dietary choices can affect health. This study used statistical modelling to investigate how dietary choices may affect life expectancy.

Methods

Mortality rates from the Global Burden of Disease study, meta-analyses, and life table methodology, were used to predict how dietary changes from a typical Western Diet (WD) to a healthier diet might influence life expectancy.
Sustained changes in fruits, vegetables, whole grains, refined grains, nuts, legumes, fish, eggs, milk/dairy, red meat, processed meat, and sugar-sweetened beverages were examined.
The authors defined two styles of eating, naming them the optimised diet (OD) and the feasibility approach diet (FAD).
OD had a higher than usual intake of whole grains, legumes, fish, fruits, vegetables, and nuts and lower intakes of red and processed meats, sugar-sweetened beverages, and refined grains.
FAD was between a WD and OD on intakes of the above listed foods.
Regions examined were the United States, China and Europe.

Results

Changing from a WD at age 20 increased life expectancy, with the greatest gains seen with the OD.
The life expectancy of men and women in Europe aged 20 increased with sustained adherence to the OD by >10 y (men: 13.7 y and women: 10.4 y).
The life expectancy of men and women in Europe aged 20 increased with the FAD (women: 5.9 y and men: 7.6 y).
Early adoption of the OD resulted in greater life expectancy gains of men and women in Europe (aged 60: women, 5.9 y; men, 7.6 y. Aged 80: women, 2 y ; men, 1.8 y).
When changing from a typical WD to an optimised diet, the largest gains in life expectancy were made by increasing legumes, whole grains and nuts consumption, while reducing red and processed meat consumption.
Effects reduced with increasing age.

• Gains in life expectancy differed between countries with those in the United States benefiting the most from dietary changes.

The quality of evidence was rated as moderate for both the optimised and feasibility approach diets.

Conclusion

Sustained changes from a WD to an optimised or more feasible way of eating may increase life expectancy, especially if adopted early in life.

Clinical practice applications

Changes from a WD to one with high amounts of legumes, whole grains, and nuts, and less red and processed meats may increase life expectancy.
No assessments were made on the effects on disease.

Considerations for future research

Whilst life expectancy increases can give some indication of health, the study did not look at the occurrence of disease.
Future research should consider making an assessment on occurrence of disease.

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Abstract

BACKGROUND

Interpreting and utilizing the findings of nutritional research can be challenging to clinicians, policy makers, and even researchers. To make better decisions about diet, innovative methods that integrate best evidence are needed. We have developed a decision support model that predicts how dietary choices affect life expectancy (LE).

METHODS AND FINDINGS

Based on meta-analyses and data from the Global Burden of Disease study (2019), we used life table methodology to estimate how LE changes with sustained changes in the intake of fruits, vegetables, whole grains, refined grains, nuts, legumes, fish, eggs, milk/dairy, red meat, processed meat, and sugar-sweetened beverages. We present estimates (with 95% uncertainty intervals [95% UIs]) for an optimized diet and a feasibility approach diet. An optimal diet had substantially higher intake than a typical diet of whole grains, legumes, fish, fruits, vegetables, and included a handful of nuts, while reducing red and processed meats, sugar-sweetened beverages, and refined grains. A feasibility approach diet was a midpoint between an optimal and a typical Western diet. A sustained change from a typical Western diet to the optimal diet from age 20 years would increase LE by more than a decade for women from the United States (10.7 [95% UI 8.4 to 12.3] years) and men (13.0 [95% UI 9.4 to 14.3] years). The largest gains would be made by eating more legumes (females: 2.2 [95% UI 1.1 to 3.4]; males: 2.5 [95% UI 1.1 to 3.9]), whole grains (females: 2.0 [95% UI 1.3 to 2.7]; males: 2.3 [95% UI 1.6 to 3.0]), and nuts (females: 1.7 [95% UI 1.5 to 2.0]; males: 2.0 [95% UI 1.7 to 2.3]), and less red meat (females: 1.6 [95% UI 1.5 to 1.8]; males: 1.9 [95% UI 1.7 to 2.1]) and processed meat (females: 1.6 [95% UI 1.5 to 1.8]; males: 1.9 [95% UI 1.7 to 2.1]). Changing from a typical diet to the optimized diet at age 60 years would increase LE by 8.0 (95% UI 6.2 to 9.3) years for women and 8.8 (95% UI 6.8 to 10.0) years for men, and 80-year-olds would gain 3.4 years (95% UI females: 2.6 to 3.8/males: 2.7 to 3.9). Change from typical to feasibility approach diet would increase LE by 6.2 (95% UI 3.5 to 8.1) years for 20-year-old women from the United States and 7.3 (95% UI 4.7 to 9.5) years for men. Using NutriGrade, the overall quality of evidence was assessed as moderate. The methodology provides population estimates under given assumptions and is not meant as individualized forecasting, with study limitations that include uncertainty for time to achieve full effects, the effect of eggs, white meat, and oils, individual variation in protective and risk factors, uncertainties for future development of medical treatments; and changes in lifestyle.

CONCLUSIONS

A sustained dietary change may give substantial health gains for people of all ages both for optimized and feasible changes. Gains are predicted to be larger the earlier the dietary changes are initiated in life. The Food4HealthyLife calculator that we provide online could be useful for clinicians, policy makers, and laypeople to understand the health impact of dietary choices.

Patient Centred Factor

Mediators: Poor diet

Clinical Imbalances

Gastro-intestinal

Modifiable Lifestyle Factors

Diet

Nutrition Evidence Keywords

Western diet Life expectancy Modelling Population study

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