In a recent study published in the journal Science of the Total Environment, researchers looked at the environmental impact of following a Mediterranean diet with reduced energy intake for one year in subjects with metabolic syndrome.
Findings revealed that the intervention led to significant reductions in acidification, eutrophication and land use, with dietary adherence and calorie reduction playing an important role in mediating these environmental benefits.
Study: Environmental impact of a nutritional intervention based on a reduced-energy Mediterranean diet. Image credit: leonori / Shutterstock
background
Climate change poses serious threats to public health, including rising temperatures, changing precipitation patterns, increased droughts, more intense heat waves, and the spread of diseases such as dengue fever and malaria.
It will also affect agriculture and livestock production, reducing food quantity and quality. With the world's population expected to reach nearly 10 billion by 2050, food demand will increase, intensifying the environmental impacts of a food system that is a major contributor to greenhouse gas emissions, eutrophication, acidification, freshwater use and biodiversity loss.
The Food and Agriculture Organization of the United Nations defines sustainable diets as essential to promote nutrition and food security while minimizing environmental damage and to mitigate these impacts.
Previous studies have shown that diets lower in animal foods and higher in plant foods are healthier and have a smaller environmental impact, but there is a need to study specific dietary interventions that can effectively reduce environmental impact.
About the Research
This study addressed an existing research gap by investigating the environmental benefits of a Mediterranean diet with reduced energy intake in older Spanish people with metabolic syndrome, focusing on its potential to reduce greenhouse gas emissions, acidification, eutrophication and land use.
The study utilized data collected during the PREDIMED-Plus trial, a multicenter, randomized, open-label, 8-year study conducted in Spain that included 6,874 participants, men aged 55-75 years and women aged 60-75 years, all of whom had metabolic syndrome but no history of cardiovascular disease.
Participants had a body mass index (BMI) between 27 and 40 kg/m² and met three or more criteria for metabolic syndrome. They were randomly assigned to receive a Mediterranean diet (MedDiet) with reduced energy expenditure, physical activity and behavioral guidelines, or a control group receiving advice on the MedDiet without weight loss promotion.
Dietary intake was assessed using a validated 143-item food frequency questionnaire (FFQ) and dietary adherence was measured using the Panagiotakos dietary score.Environmental impact indicators such as greenhouse gas emissions, energy use, land use, acidification and eutrophication were calculated based on the EAT-Lancet Commission tables.
Data were analyzed using linear regression models adjusting for sex, age, education level, and baseline calorie intake. Mediation analyses were conducted to determine the extent to which changes in calorie intake and adherence to the diet influenced reductions in environmental impacts.
Investigation result
The study found significant reductions in environmental impacts between the intervention and control groups, including greater reductions in acidification (-9.9 g sulfur dioxide equivalent vs. -13.3 g sulfur dioxide equivalent), eutrophication (-4.0 g phosphate equivalent vs. -5.4 g phosphate equivalent), and land use (-1.8 m2 vs. -2.7 m2) in the intervention group.
Additionally, the IG experienced a greater reduction in caloric intake (−178.4 vs. −73.3 kcal) and improved dietary adherence in the intervention group (1.2 points vs. 0.5 points).
Meat was the main contributor to environmental impacts in both groups, but seafood contributed significantly to greenhouse gas emissions in the IG.
Mediation analyses showed that calorie reduction partially mediated the observed relationships between the intervention and reductions in acidification, eutrophication, and land use, explaining 55%, 51%, and 38% of the total associations, respectively.
Dietary adherence partially mediated the relationships between these factors and fully mediated those for greenhouse gas emissions (56%) and energy use (53%).
Conclusion
This study highlights the positive impact of a one-year Mediterranean dietary intervention with reduced energy intake on environmental sustainability, particularly in reducing acidification, eutrophication and land use.
This study innovatively explores the role of calorie reduction and adherence to a Mediterranean diet in mediating this relationship, a new approach in the field. Despite limitations such as data variability and potential recall bias, the strengths of this study lie in its real-world assessment of environmental effects and its large sample size.
The findings highlight the potential of Mediterranean diet interventions to mitigate environmental damage, particularly meat consumption, but challenges remain in standardizing environmental impact databases and taking into account regional differences.
Future research could expand on these findings to explore a wider range of dietary patterns and their environmental impacts, improving our understanding of the diet-environment-health triple whammy and promoting sustainable nutrition choices.
Overall, this study highlights the potential of Mediterranean diet interventions to enhance human health and environmental sustainability.
Journal References:
Environmental impact of a nutritional intervention based on a reduced-energy Mediterranean diet. Álvarez-Álvarez, L., Rubín-García, M., Vitelli-Strelli, F., García, S., Bouzas, C., Martínez-González, M. A., Colella, D., Salas-Salvado, J., Marcampo, M., Martínez, J. A., Alonso-Gómez, A. M., Wärnberg, J., Vioque, J., Romaguera, D., López-Miranda, J., Estruque, R., Tinajones, F. J., Lapetla, J., Serra-Majem, L., Bueno-Cabanillas, A., Martín-Sánchez, V. Integrated Environmental Sciences (2024). DOI: 10.1016/j.scitotenv.2024.172610, https://www.sciencedirect.com/science/article/pii/S0048969724027566
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