Abstract
Food production accounts for 30% of global greenhouse gas (GHG) emissions. Less environmentally sustainable diets are also often more processed, energy-dense and nutrient-poor. To date, the environmental impact of diets have mostly been based on a limited number of broad food groups.
Generated Summary
This research investigates the variations in greenhouse gas (GHG) emissions associated with individual diets in the United Kingdom, exploring the relationship between GHG emissions, nutrient intake, and demographic characteristics. The study employs a comprehensive approach, linking GHG emissions data to over 3000 food items within the UK Composition Of Foods Integrated Dataset (COFID). The research utilized an online dietary assessment tool, myfood24, to analyze the diets of 212 adults over three 24-hour periods. The primary goal was to assess the environmental impact of individual diets, identify associations between GHG emissions and dietary patterns, and determine the additional information needed for accurate individual-level dietary assessments. The methodology included linking GHG emissions values from existing literature to the COFID database, calculating mean GHG emissions per day for each participant, and evaluating the associations between GHG emissions, nutrient requirements, and demographic characteristics. The study focused on GHG emissions as the primary environmental indicator to establish connections between personal and planetary health.
Key Findings & Statistics
- The database used in the study included 3287 generic food items, with GHG emissions values assigned to 3233 (98%) items.
- The cohort consisted of 212 participants, with 60% being female and 7% identifying as vegetarian.
- The mean age of the participants was 43 years.
- Participants collectively consumed 1313 different food items.
- Mean daily diet-related GHG emissions were 7.4 kg CO2eq/day (95% CI 6.7 to 8.1), with a geometric mean of 6.2 kg CO2eq/day (95% CI 5.8 to 6.7).
- Meat accounted for 32% of diet-related GHG emissions.
- Drinks contributed 15% to GHG emissions, followed by dairy at 14%, and cakes, biscuits & confectionery at 8%.
- Men had 41% higher GHG emissions than women (95% CI 20% to 64%).
- Non-vegetarian diets had 59% higher GHG emissions than vegetarian diets (95% CI 18% to 115%).
- Participants exceeding the RNI for saturated fat had diets associated with higher GHG emissions (mean difference 22%, 95% CI 1% to 48%).
- Participants not achieving the RNI for carbohydrates had diets associated with higher GHG emissions (mean difference 56%, 95% CI 26% to 94%).
- Participants exceeding the RNI for sodium had substantially higher diet-related GHG emissions (mean difference 74%, 95% CI 13% to 167%).
Other Important Findings
- Drinks, cakes, biscuits, and confectionery accounted for 24% of total diet-related GHG emissions, indicating that a significant portion of emissions comes from optional foods and drinks.
- Higher GHG emissions in men were primarily due to greater meat intake.
- There was no significant difference in GHG emissions between people under 40 and those 40 or over.
- There was no significant difference in GHG emissions between overweight/obese and non-overweight/obese individuals.
- Vegetarians had lower GHG emissions associated with cakes, biscuits, and confectionery.
- Diets meeting RNIs for saturated fats, carbohydrates, and sodium generally had lower GHG emissions.
Limitations Noted in the Document
- The study’s GHG emissions values were based on data up to the point of retail and did not include stages like transport to home and food waste, potentially underestimating the total impact.
- The assessment relied on self-reported dietary data, which may be subject to inaccuracies.
- The study’s cohort included a limited number of vegetarians, affecting the reliability of findings for this group.
- The study used GHG values from multiple sources, and the consistency of impact estimates for each factor, such as transport, was uncertain.
- The accuracy of GHG emission estimates may change with shifts in trade patterns or the effects of events like Brexit or the COVID-19 pandemic.
- The study was limited by a focus on GHG emissions and did not include other environmental indicators.
Conclusion
The study’s findings highlight the substantial impact of individual dietary choices on GHG emissions, with meat consumption being a primary driver. The research underscores the potential for promoting sustainable dietary patterns by focusing on plant-based diets and reducing consumption of less nutritious foods. Policies encouraging sustainable diets should concentrate on plant-based options and reducing less nutritious snack items. Key findings show a strong connection between personal health and environmental impacts, where healthier diets tend to have lower GHG emissions. Further, the study found that meeting recommended nutrient intakes was generally associated with lower GHG emissions, indicating that optimized diets can provide both nutritional and environmental benefits. This research emphasizes the importance of moving beyond general advice at the population level to provide specific guidance at the individual level. Future research could enhance the precision of environmental impact assessments by integrating additional factors like brand, production methods, and origin data. The study also points out the need for comprehensive dietary assessment methods that consider a wide range of food items and their environmental impacts. The findings support the idea that shifts towards plant-based diets and dietary changes could lower the greenhouse gas emissions of diets. The study’s findings also emphasize the role of policies in promoting sustainable dietary patterns and suggest that a combination of dietary optimization and policy changes could result in significant improvements in both environmental sustainability and public health.