Article - Association between the Mediterranean Diet Score and Healthy Life Expectancy: A Global Comparative Study.

Plain Language Summary

Life expectancy (LE) has increased significantly whilst since 2020, according to the World Health Organisation, healthy life expectancy (HALE) has not kept pace, due to the increase in non-communicable diseases. The Mediterranean Diet (MD) is recommended as a healthy dietary pattern by British and US guidelines. The aim of this cross-sectional and longitudinal study covering 130 countries was to compare the relationship between the Mediterranean Diet Score (MDS, adherence to the MD) and LE and HALE. The MDS was calculated by applying 1 point if intakes of fruit, vegetables, legumes, grains, fish and olive oil were above the median (0 if below) and intake of meat and dairy (considered detrimental to health) below the median (1 if above). Alcohol intakes of 10-50g also scored 1 point. For cross-sectional analysis data from 2009 were used whilst 2009-2019 data were used for longitudinal analysis. In both longitudinal and cross-sectional analysis, a higher MDS was correlated with higher LE and HALE. The country with the highest LE and HALE was Japan. The authors conclude that promotion a MD could extend HALE on a population level.

Expert Review

Reviewer: Karin Elgar

6th Feb 2025

Conflict of interest

None

Take home message

On a population level, adherence to a MD could be promoted to support healthy longevity.

Evidence category

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

Summary review

Introduction

Average life expectancy (LE) continues to increase worldwide whilst healthy life expectancy (HALE) has not kept up with this increase. This is associated with a rise in non-communicable diseases (NCD).
Lifestyle factors, including diet, are thought to contribute to NCDs.
A Mediterranean diet (MD) is recommended by authorities including the National Health Service in the UK.
The aim of this study was to evaluate the relationship between the MD score and HALE and average LE.

Methods

This is an international comparative study including data from 130 countries.
Data from the Global Burden of Diseases, Injuries, and Risk Factors study 2019 (GBD2019) were used to estimate HALE.
The Word Bank database was used to estimate LE.
Data from the Food and Agriculture Organization Corporate Statistical Database (FAOSTAT) were used to calculate the average adherence to a MD pattern, the MD score, per country.
MD scores, which can range from 0-9, were calculated by giving +1 point for above median supplies of vegetables, legumes, fruits and nuts, cereals, fish, and olive oil as well as for a wine intake of 1-3 glasses, whilst foods considered “detrimental” (dairy and meat) scored -1 if above median.
Potential confounding factors which were adjusted for included BMI, obesity rates, smoking, physical activity, years of education, percentage of the Muslim population and air pollution.

Results/discussion

Japan had the highest HALE and LE and a MD score of 4.
After controlling for confounding factors, cross-sectional analysis showed a significant positive correlation between MD score and both LE (p=0.037, β=0.906, 95% CI [0.065, 1.747]) and HALE (p=0.011, , β=0.875, 95% CI [0207, 1.544]).
Likewise, longitudinal analysis (2009-2019) also showed a positive correlation between MD score and LE (p=0.03, β=0.621, 95% CI [0.063, 1.178]) and HALE (p=0.004, β=0.694, 95% CI [0.227, 1.161]).

Conclusion

The authors conclude that the promotion of a MD and increasing the availability of the relevant food groups could help increase the MD score and extend HALE on a population level.

Clinical practice applications

Whilst the data suggest a positive effect of the MD on HALE and LE, it is important to note that the data were gathered on a population level which may not necessarily be extrapolated to 1-2-1 clinical practice.
On a population level, adherence to a MD could be promoted.

Considerations for future research

It is important to note that observational research can only determine correlations, not causation, and intervention studies would be valuable to confirm that adoption of an MD can support health and life expectancy.
From the standpoint of nutritional therapy practice, intervention studies could help identify which client groups may benefit from adherence to a MD.

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Abstract

OBJECTIVES

Extending healthy life expectancy (HALE), defined as the average number of years that a person can expect to live in "full health" by taking into account years lived in less than full health due to disease and/or injury, is a common topic worldwide. This study aims to clarify the relationships between the Mediterranean diet score (MDS) and life expectancy (LE) and HALE globally using publicly available international data.

SETTING

Analyses were conducted on 130 countries with populations of 1 million or more for which all data were available. Individual countries were scored from 0 to 9 to indicate adherence to the Mediterranean diet according to the MDS scoring method. The supply of vegetables, legumes, fruits and nuts, cereals, fish, and olive oil per 1,000 kcal per country was calculated based on the Food and Agriculture Organization Corporate Statistical Database, with a score of 1 for above the median and 0 for below. The same method was used to calculate scores of presumed detrimental components (meat and dairy), with consumption below the median given a value of 1, and consumption above the median given a value of 0. For ethanol, a score of 1 was given for 10g to 50 g of consumption. We investigated the cross-sectional associations between the MDS and LE and HALE at birth in 2009, and the longitudinal associations between the MDS in 2009 and LE and HALE between 2009 and 2019, controlling for covariates at baseline using linear mixed models.

RESULTS

In the cross-sectional analysis, the MDS was significantly positively associated with LE (β=0.906 [95% confidence interval, 0.065-1.747], p=0.037) and HALE (β=0.875 [0.207-1.544], p=0.011) after controlling for all covariates. The longitudinal analysis also revealed significantly positive associations between the MDS and LE (0.621 [0.063-1.178], p=0.030) and HALE (0.694 [0.227-1.161], p=0.004) after controlling for all covariates.

CONCLUSION

The present study, based on an analysis using 10 years of international data, showed that countries with a higher MDS showed a positive association with HALE.