Numerous studies have assessed the environmental impact of current diets or dietary shifts, most using greenhouse gas emission (GHGE) as an environmental indicator. These studies principally showed that meat and dairy are among the largest contributors to GHGE; whereas high intake of fruits, vegetables (F&V), and legumes/pulses/nuts consumption is associated with the lowest GHGE1-3.

In this study, we aimed to identify the dietary changes needed to achieve a nutritionally adequate diet (i.e. which fulfill of a set of 32 nutrient recommendations) with lower GHGE across five European countries: Finland, France, Italy, Sweden and the UK. Dietary data were derived from national food consumption surveys, including more than 1000 individuals by country (women and men/18-64 years). Average consumption, GHGE (gCO2eq) and nutritional composition of 151 food items (based on an adapted FoodEx* food classification) were estimated for each country and gender. Linear programming was used to design national and gender specific nutritionally adequate (fulfillment of a set of 32 nutrient recommendations) diets in three different scenarios:

• Scenario 1: Departing the least from observed diet without applying GHGE reductions
• Scenario 2: Minimizing the GHGE
• Scenario 3: Departing the least from observed diet and applying a 30% GHGE reduction.

Energy content and GHGE in observed diets and after achieving nutrient recommendations

In the observed diets, across countries, energy content ranged from 1591 to 1888 kcal/day in women, and from 2109 to 2360 kcal/day in men. GHGE ranged from 3403 to 4321 g CO2 eq/day in women, and from 4636 to 5793 CO2 eq/day in men. Meat was the main contributor to GHGE in all observed diets except for Finnish women where it was dairy. When nutrient recommendations were fulfilled (scenario 1) for women, GHGE increased in the modeled diets, except in the UK. For men, the same increase in GHGE was seen for all countries except Italy and Finland. For both genders, the majority of fooditem quantities did not need to change, except for UK women who needed to change quantities for 53% of food items. Their food habits were associated with the lowest GHGE compared with other countries and gender, but they also had the most inadequate intakes of magnesium, vitamin E, vitamin C, folates, zinc, iron, calcium, potassium, and fiber.

GHGE decrease induce modifications in quantity of food item

Depending on country and gender, a decrease of 62-78% GHGE was theoretically achievable (scenario 2) but induced a modification in quantity of at least 99% of food items from observed diets. This has a strong risk of compromising the cultural acceptability of the diet.

Increased consumption of F&V and starchy foods is needed for a sustainable diet

Across Europe, dietary changes including lower consumption of fat, sugar and alcoholic beverages, along with increased consumption of F&V and starchy foods, were needed to reach a nutritionally adequate diet with a 30% reduction of GHGE (scenario 3). The study also found that there’s a need for modifications in the type of animal-based products depending on the dietary habits of the populations. For example, in this scenario, contribution of dairy products to energy intakes is increased in Sweden and France for both men and women, but decreased in UK, Finland and Italy for women. In addition, energy intakes from fish is increased in France and Italy, but decreased in Finland.

This study highlights the importance to take into consideration environment, country, gender and social and cultural acceptability before setting nutritional goals to reach a nutritionally adequate diet with lower GHGE.

* FoodEx is a hierarchical system based on 20 main food categories that are further divided into subgroups up to a maximum of 4 levels. It builds on different
food description and classification systems.

Based on: F. Vieux, M. Perignon, R. Gazan and N. Darmon. Dietary changes needed to improve diet sustainability: are they similar across Europe? European
Journal of Clinical Nutrition 72, 951–960 (2018).