Mediterranean diet reduces environmental impact and improves metabolic health, research shows

This is evident from a recent study published in the journal Science of the total environment, researchers examined the environmental impact of a Mediterranean diet with reduced energy intake for one year in participants with metabolic syndrome.

Their results indicate that the intervention was associated with significant reductions in acidification, eutrophication and land use, with diet adherence and calorie reduction playing a key role in mediating these environmental benefits.

Study: Effect of a nutritional intervention based on a low-energy Mediterranean diet on environmental impact. Image credits: leonori / Shutterstock

Background

Climate change poses a serious threat to public health, including rising temperatures, altered rainfall patterns, increased droughts, more intense heat waves and increased transmission of diseases such as dengue and malaria.

It also affects agriculture and livestock farming, reducing the quantity and quality of food. With the world’s population expected to reach nearly 10 billion people by 2050, the need for food will escalate, increasing the environmental impacts of food systems, which are major contributors to greenhouse gas emissions, eutrophication, acidification, freshwater use and biodiversity loss .

The Food and Agriculture Organization of the United Nations defines sustainable diets as crucial for mitigating these impacts by promoting nutrition and food security while minimizing damage to the environment.

Previous research shows that diets with fewer animal products and more plant foods are healthier and have a smaller environmental footprint. However, specific nutritional interventions that can effectively reduce environmental impacts need to be explored.

About the study

This study addressed existing research gaps by examining the environmental benefits of a Mediterranean diet with reduced energy intake in older Spanish adults with metabolic syndrome. It focused on its potential to reduce greenhouse gas emissions, acidification, eutrophication and land use.

This study used data collected during the PREDIMED-Plus study, a multicenter, randomized (non-blinded) eight-year study conducted in Spain. The study included 6,874 participants, aged 55-75 years for men and 60-75 years for women, all with metabolic syndrome but without any form of cardiovascular disease in their medical history.

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 an intervention group, which received a Mediterranean diet (MedDiet) with reduced energy and physical activity and behavioral therapy guidelines, or to a control group, which received MedDiet advice without weight loss promotion.

Dietary intake was assessed using a validated 143-item Food Frequency Questionnaire (FFQ), and adherence was measured using the Panagiotakos Diet Score. Environmental impact indicators, including greenhouse gas emissions, energy consumption, land use, acidification and eutrophication, were calculated based on the EAT-Lancet Commission tables.

The data were analyzed using linear regression modeling adjusting for sex, age, education level and baseline calorie intake. A mediation analysis was conducted to determine the extent to which changes in caloric intake and diet adherence mediated the reduction in environmental impact.

Findings

The study showed that there was a significant decrease in environmental impact factors between the intervention and control groups. Specifically, the intervention group showed greater reductions in acidification (−13.3 compared to −9.9 g sulfur dioxide equivalent), eutrophication (−5.4 compared to −4.0 g phosphate equivalent) and land use (−2 .7 compared to -1.8 m2).²).

Additionally, IG experienced a significant decrease in calorie intake (-178.4 compared to -73.3 kilocalories) and higher dietary adherence for the intervention group (1.2 compared to 0.5 points).

Meat was the largest contributor to environmental impact factors in both groups, while fish and seafood contributed more to greenhouse gas emissions in IG.

The mediation analysis showed that calorie reduction partially mediates the observed relationship between intervention and reduction in acidification, eutrophication and land use, explaining 55%, 51% and 38% of the total association, respectively.

Diet adherence also partially mediated the relationship between these factors, with full mediation for greenhouse gas emissions (56%) and energy expenditure (53%).

Conclusions

This study highlights the positive impact of a one-year MedDiet intervention with reduced energy intake on environmental sustainability, particularly in reducing acidification, eutrophication and land use.

It innovatively examines the role of calorie reduction and MedDiet adherence in mediating this relationship, a novel approach in the field. Despite limitations such as the variability of the data and possible recall biases, the strengths of the study lie in the real assessment of environmental impact and the large sample size.

The findings highlight the potential of MedDiet interventions to reduce environmental damage, especially with regard to meat consumption. However, challenges remain in standardizing environmental impact databases and accounting for regional differences.

Future research could extend these findings, explore broader dietary patterns and their environmental implications, promote a deeper understanding of the nutrition, environment, and health trilemma, and promote sustainable food choices.

Overall, this study underlines the potential of MedDiet interventions to improve human health and environmental sustainability.