Lifestyle Works

In a recent study from the University of Leeds in the UK, 23 per cent of all diet-related greenhouse gas emissions are accounted for in foods like cakes, biscuits and lollies, alcoholic drinks and caffeinated products like tea and coffee. Below are excerpts from this fascinating study.

Holly L. Rippin, Janet E. Cade, Lea Berrang-Ford, Tim G. Benton, Neil Hancock, Darren C. Greenwood
Published: November 23, 2021

Providing populations with healthy, nutritionally adequate diets that are environmentally sustainable is a global challenge, with food production accounting for 30% of greenhouse gas (GHG) emissions. As production efficiency has increased, food-system efficiency in sustainably providing nutritious food has declined, and the cost of dietary ill-health and environmental degradation now exceeds the economic value of agriculture… The environmental costs of our diets include impacts on air and water quality, water availability, soil health, biodiversity loss and homogenization of landscapes. They also contribute to poor human health through exposure to poor air quality, antimicrobial resistance from antibiotic use and poor dietary health associated with non-communicable diseases.

At an individual-level, personal health is partly reliant on planetary health and vice versa, through making low impact lifestyle choices. Unhealthy, environmentally unsustainable diets are often processed, energy-dense and nutrient-poor, for example high in saturated fat. A healthy diet based on vegetables, fruit, wholegrains, legumes, nuts and unsaturated oils, with small amounts of seafood and poultry, is also a sustainable one. This implies diets should contain minimal red meat, processed meat, with less added sugar or refined grains. Wider use of this type of diet could prevent a fifth of premature adult deaths whilst reducing GHG emissions by four fifths. More sustainable diets have also been shown to have better diet quality scores based on a range of indicators. However, research supporting this is based on a limited number of food items or food groups. This can lead to conflicting advice, such as sugar-sweetened beverages having low environmental impact.

Mean greenhouse gas emissions associated with a person's daily diet were 7.4 kg CO2eq/day. The largest overall contribution to diet-related GHG emissions came from meat (32% of total diet-related GHG emissions), with drinks (15%), dairy (14%), and cakes, biscuits & confectionery (8%) also contributing relatively high amounts. The GHG emissions from drinks were dominated by tea, coffee and alcoholic beverages which, together with cakes, biscuits and confectionary, suggest 24% of total diet-related GHG emissions derive from largely optional foods and drinks.

The diets of men were associated with 41% higher GHG emissions than woman, driven by differences in meat intake and to a lesser extent by GHG emissions from drinks.

Non-vegetarian diets were associated with 59% higher GHG emissions than vegetarians with the difference again driven by meat intake. Vegetarians also had lower GHG emissions associated with cakes, biscuits and confectionery, reflecting healthier dietary patterns more generally. Small increases in GHG emissions associated with fruit and vegetables and other foods amongst vegetarians did not detract from the lower contribution from meat and fish.

This has allowed us to quantify diet-related GHG emissions and compare different population subgroups. We found that nearly a quarter of GHG emissions were associated with elements of the diet that are nutritionally optional, such as drinks, cakes, biscuits and confectionery. We also confirmed the lower GHG emissions from vegetarian diets compared to omnivorous diets, which were largely attributable to differences in meat consumption. Our findings are consistent with previous reviews that found animal-based foods had greatest environmental impact, specifically beef.

These findings confirm those based on broader food groupings in that red meat is a major driver of dietary-related GHG emissions.

In conclusion, this study addresses the environmental impact of diet on the individual level, based on the GHG emissions value of foods consumed. It has tested and established the feasibility of populating a large online food and nutrient product database with GHG emissions values. Meat was the dominant driver for diet-related GHG emissions, explaining most of the differences between GHG emissions associated with vegetarian and non-vegetarian diets, and between the differences in GHG emissions associated with the diets of men and women. However, drinks such as tea and coffee, and cakes, biscuits and confectionery, explained a quarter of diet-related GHG emissions, and present alternative routes to reduce diet-related GHG emissions. Those who met dietary recommendations had generally lower diet-related GHG emissions, suggesting future policies to encourage sustainable dietary patterns and plant-based diets could be good for both individual and planetary health.