Abstract
Food choices influence health status, but also have a great impact on the environment. The production of animal-derived foods has a high environmental burden, whereas the burden of refined carbohydrates, vegetables and fruit is low. The aim of this study was to investigate the associations of greenhouse gas emission (GHGE) and land use of usual diet with mortality risk, and to estimate the effect of a modelled meat substitution scenario on health and the environment. The usual diet of 40011 subjects in the EPIC-NL cohort was assessed using a food frequency questionnaire. GHGE and land use of food products were based on life cycle analysis. Cox proportional hazard ratios (HR) were calculated to determine relative mortality risk. In the modelled meat-substitution scenario, one-third (35 gram) of the usual daily meat intake (105 gram) was substituted by other foods. During a follow-up of 15.9 years, 2563 deaths were registered. GHGE and land use of the usual diet were not associated with all-cause or with cause-specific mortality. Highest vs. lowest quartile of GHGE and land use adjusted hazard ratios for all-cause mortality were respectively 1.00 (95% CI: 0.86-1.17) and 1.05 (95% CI: 0.89-1.23). Modelled substitution of 35 g/d of meat with vegetables, fruit-nuts-seeds, pasta-rice-couscous, or fish significantly increased survival rates (6-19%), reduced GHGE (4-11%), and land use (10-12%).
Generated Summary
This study, published in Environmental Health, investigated the relationship between greenhouse gas emissions (GHGE) and land use associated with usual diet and mortality risk within the EPIC-NL cohort, a prospective study. The research aimed to assess how dietary choices impact both environmental sustainability and health outcomes. The methodology involved assessing the usual diets of 40,011 participants using a food frequency questionnaire and calculating GHGE and land use based on life cycle analysis. Cox proportional hazard ratios (HR) were computed to determine relative mortality risks. Additionally, the study evaluated the effects of a modeled meat substitution scenario on health and environmental outcomes. The study used a comprehensive approach, incorporating dietary assessments, environmental impact assessments, and statistical analyses to explore the complex relationships between diet, environmental impact, and health within a large cohort over a considerable follow-up period. The core focus was on understanding how different dietary patterns influence both environmental footprints and health outcomes, particularly in relation to mortality risk. The findings contribute to the ongoing discussion on the sustainability of food systems and the potential health benefits of adopting more environmentally friendly dietary habits.
Key Findings & Statistics
- The study involved 40,011 subjects in the EPIC-NL cohort.
- A follow-up of 15.9 years resulted in 2563 deaths.
- The observed EPIC-NL cohort median value of GHGE was 3.87 kg CO2-equivalents/d.
- The observed EPIC-NL cohort median value for land use was 3.61 m²*year/d.
- Total meat intake accounts for approximately 30% of total dietary-derived GHGE and land use.
- Dairy accounts for 25% of GHGE and 17% of land use.
- Beverages account for 13% of GHGE and 16% of land use.
- The HR (95% confidence interval) of highest versus lowest quartile of GHGE was 0.76 (0.68-0.85) in crude analyses. After multivariable adjustment, the HR was 1.00 (0.86-1.17).
- The HR of highest versus lowest quartile of GHGE for adjusted cause-specific mortality models were: 1.01 (0.86-1.34) for cancer, 0.90 (0.63-1.28) for CVD, 1.12 (0.52-2.39) for respiratory diseases, and 0.91 (0.64-1.30) for other causes of death.
- In crude analysis, the HR of highest versus lowest quartile for total land use of usual diet was 0.74 (0.66-0.82). After multivariable adjustment, the HR was 1.05 (0.89-1.23).
- Cause-specific adjusted HRs for land use were: 1.10 (0.88-1.37) for cancer, 1.07 (0.75-1.54) for CVD, 1.19 (0.58-2.46) for respiratory diseases, and 0.88 (0.61-1.27) for deaths by remaining causes.
- Reducing meat intake by 35 grams with a substitution of pasta-rice-couscous was associated with an 11% (95% CI, 4% to 16%) lower risk of all-cause mortality.
- Replacing meat with vegetables was associated with a 9% (95% CI, 3% to 15%) lower risk of all-cause mortality.
- Substituting meat with fruit-nuts-seeds was linked to a 6% (95% CI, 1% to 10%) lower risk.
- A shift to 35 gram more milk-based dessert was associated with a borderline non-significant 4% (95% CI, 0% to 9%) lower risk.
- Substitution by fish was associated with a 19% (95% CI, 3% to 33%) lower risk.
- 35 gram more cheese instead of meat (HR: 6% (95% CI, -4% to 14%)) or potatoes (HR: 0% (95% CI, -6% to 7%)) was not associated with a lower all-cause mortality risk.
- Reducing intake of total meat by 35 gram without replacement was associated with a 4% (95% CI, 2% to 7%) lower mortality risk.
Other Important Findings
- The study found no significant associations between dietary-derived GHGE and land use with all-cause or cause-specific mortality.
- The scenario study indicated that substituting meat with other major food groups was associated with a lower mortality risk and a reduced environmental burden.
- Substituting 35 g/d of meat with vegetables, fruit-nuts-seeds, fish, or pasta-rice-couscous showed a significant reduction in mortality risk and environmental burden.
- The environmental impact of the usual diet was not associated with all-cause or cause-specific mortality.
- Meat intake contributed significantly to dietary-derived GHGE and land use.
- A reduction in meat intake, with substitutions of vegetables, fruits, or fish, was associated with increased survival rates and reduced GHGE and land use.
Limitations Noted in the Document
- The study’s reliance on a food frequency questionnaire (FFQ) for dietary assessment is a potential limitation, as FFQs are designed to rank people according to their diet, which may not fully capture actual intake.
- The study acknowledges that the environmental impact within food groups can vary depending on production methods, transport, and other factors, which were not fully accounted for.
- The study’s focus on substitutions of equivalent quantities in grams rather than iso-caloric or nutritional component equivalency limits the scope of the findings.
- The generalizability of the results to the broader population could be limited, given the specific dietary habits of the Dutch population.
- The study design did not consider the variety of distributions of environmental impact for every stage of the production process, which would allow for variance estimation.
Conclusion
The primary conclusion of this study is that, within the dietary range of the studied Dutch cohort, the environmental impact of the usual diet, measured by GHGE and land use, was not significantly associated with all-cause or cause-specific mortality. This suggests that, in this population, a diet with a lower environmental impact is not necessarily associated with better health outcomes in terms of mortality. However, the study found that a modeled reduction of meat intake, and its replacement with vegetables, fruits, fish, or cereal-rice-couscous, did result in both a reduction in GHGE and land use, and decreased all-cause mortality risk. This points to the potential benefits of shifting dietary patterns towards more sustainable food choices. The study emphasized that the reduction of meat consumption can influence both health and environmental aspects, highlighting the complex interplay between dietary choices, environmental impact, and health outcomes. The findings suggest that while the overall environmental impact of the diet may not directly correlate with mortality risk, targeted dietary changes, such as reducing meat consumption and substituting with plant-based alternatives, can provide a dual benefit by improving both health and reducing environmental burdens. The study contributes to the growing body of evidence on the complex relationships between food choices, health, and environmental sustainability, offering insights relevant to dietary guidelines and public health strategies. The study’s findings highlight the need for a nuanced approach to dietary recommendations, considering both health and environmental impacts. The results also underscore the potential of food-based policies and interventions to simultaneously promote health and environmental sustainability. The study’s emphasis on the benefits of substituting meat with plant-based foods supports the promotion of such dietary changes in public health messaging and policy. The research suggests that reducing meat consumption can have a positive impact on both individual health outcomes and environmental sustainability. This calls for continued research and implementation of policies that support these dietary transitions.