Background and Objective:
The world faces a global syndemic, in which diet is an important risk factor. The Global Diet Quality Score (GDQS) is a simple, timely and low-burden tool to track the contribution of diet to undernutrition and overnutrition globally. The Planetary Health Diet Index (PHDI) is an indicator of adherence to the EAT-Lancet Commission sustainable dietary guidelines. The present study aimed at investigating the correlation between the GDQS and PHDI in the Brazilian diet, to highlight concordances between them and shed light into the GDQS’ potential as a sustainable diet metric.

Methods:
The study was conducted in a nationally representative sample of 44,744 individuals aging ≥ 10 from the Household Budget Survey of Brazil, in which dietary data collection took place between 2017-2018, by trained interviewers using two 24-hour recalls per participant. The GDQS and PHDI were scored from the two 24-hour recall means of intake. Spearman’s correlation coefficient between the GDQS and PHDI was estimated for the whole sample and across sex, age, and income strata.

Results:
The correlation coefficient between the GDQS and PHDI was 0.21 (p<0.001), varying from 0.17 to 0.29 by strata. Women, elderly individuals, and the highest income strata had the strongest correlation between metrics (0.23, 0.26, and 0.29, respectively). Classification of food components into healthy, unhealthy in excessive amounts or unhealthy was discordant between metrics for vegetable oils, fish and seafood, low fat dairy, eggs, poultry and substitutes, red meat, and deep orange tubers.

Conclusions:
The GDQS is positively correlated with the PHDI in Brazil. Sources of discordances between metrics notably rely on the definitions of optimum intake of animal products, which should be subject to further evaluation.

Acknowledgements:
To the Sao Paulo Research Foundation (FAPESP) for funding our work (grant 2013/07607-8; 2022/08172-4), and Prof. Walter Willett (Harvard University) for the contribution.