Shift to sustainable diets could cut global mortality by 27%

By Priyanjana Pramanik, MSc.Reviewed by Lily Ramsey, LLMNov 22 2024

New study highlights the life-saving potential of the Planetary Health Diet and its role in achieving global sustainability goals.

Study: Global adherence to a healthy and sustainable diet and potential reduction in premature death. Image Credit: Phtopro/Shutterstock.com

In a recent study published in PNAS, researchers estimated how many lives could be saved if people switched from their current diets and followed the Planetary Health Diet (PHD) instead.

Their findings indicate that increasing adherence to the PHD could prevent 27% of all deaths or 15 million deaths each year, including those from neurodegenerative and cardiovascular diseases.

Background

Unhealthy diets contribute to the development of non-communicable diseases (NCDs), which lead to premature but preventable deaths around the world. Food production continues to present challenges in meeting the targets of the Paris Climate Agreement and the Sustainable Development Goals (SDGs).

To address these challenges, the EAT-Lancet Commission created a healthy and flexible reference diet, the PHD.

This diet emphasizes the consumption of unsaturated oils, nuts, legumes, whole grains, fruits, and vegetables while limiting red and processed meats, refined grains, starchy vegetables, salt, and sugar. Those who follow the PHD also consume poultry and seafood in moderate amounts.

An important focus of the PHD is switching from current diets to healthier alternatives without increasing the total energy intake, such as substituting starchy vegetables with whole grains. Adhering to the PHD can lead to measurable health improvements, including reducing the risk of cardiovascular diseases and type 2 diabetes.

Researchers also developed the Planetary Health Diet Index (PHDI) to measure adherence to the PHD and how it affects mortality. They have linked higher PHDI scores to lower risks of respiratory disease, cancer, cardiovascular disease, and overall mortality.

About the study

In this study, researchers used large datasets and improved methodology to build on previous studies and offer more precise estimates of deaths that can be prevented by shifting to healthier diets.

Data included Food Balance Sheets (FBS), which were adjusted for food waste, energy requirements adjusted for activity level, height, and weight; the Global Dietary Database (GDD) for age and sex distribution; processed meats and refined grains; and other publicly available dietary data.

Mortality data were obtained from the World Health Organization’s Global Health Estimates for 183 countries and the Global Burden of Disease study.

Researchers calculated PHDI scores based on 15 food groups, with healthy foods being given higher scores and unhealthy foods being scored poorly. Thus, this scoring system reflects the relationship between disease risk and food intake after adjusting for consumption of different food groups.

Researchers then estimated the impact that diet has on mortality using large cohort studies, calculating the PHDI for each participant and linking it to mortality.

PHDI and its components were calculated separately for different regions and countries and weighted by population. The estimated effects on mortality were calculated using simulations and hazard ratios.

Findings

Researchers estimated that in 2018, the average PHDI score was 85 out of 140, which indicated moderate adherence to the PHD. Foods such as poultry, eggs, added sugar, and dairy all scored more than 8 out of 10, while unsaturated fats, legumes, seeds, and nuts scored below 4.

Lower-middle-income countries, where consumption of whole grains, animal proteins, and dairy is high, had the highest adherence score of 92. In contrast, low-income countries had the lowest PHDI of 79, driven by the intake of saturated fats and starchy vegetables and low consumption of healthy food.

In Latin America and North America, the high consumption of added sugar and red meat combined with low intakes of healthier plant-based foods resulted in lower PHDI scores (70 and 78, respectively).

The results suggest that improving dietary quality by increasing the PHDI score to 120 could prevent 15 million premature deaths each year, accounting for 27% of all deaths. If each country could achieve a perfect PHDI (140), they could prevent an additional 6 million deaths.

Specifically, 2.5 million deaths attributed to cardiovascular disease, 2 million attributed to respiratory disease, 1.6 million attributed to infectious disease, 1.4 million deaths attributed to cancer, and 700,000 deaths attributed to neurodegenerative disease could be prevented.

Adhering to the PHD could save 1.2 million lives in low-income countries and 1.4 million in the Caribbean and Latin America. Colombia, the country with the lowest PHDI, could reduce its mortality rate by as much as 43% by improving its residents’ dietary habits. Even Iran, with the highest estimated PHDI, could reduce deaths by 13% through further improvement.

Conclusions

This study shows that while global adoption of the PHD remains far from optimal, improving the quality of diets globally could save 15 million lives each year.

This highlights the PHD as a sustainable, effective, and practical tool to reduce mortality while supporting the SDGs.