2014 study finds that vegetarian and semi-vegetarian diets are lower in GHG emissions than non-veget
[abstract]
"Greenhouse gas emissions (GHGEs) are a major consequence of our dietary choices. Assessments of plant-based compared with meat-based diets are emerging at the intersection of public health, environment, and nutrition.OBJECTIVES: : The objective was to compare the GHGEs associated with dietary patterns consumed in a large population across North America and to independently assess mortality according to dietary patterns in the same population.DESIGN: : Data from the Adventist Health Study 2 (AHS-2) were used to characterize the differential environmental and health impacts of the following 3 dietary patterns, which varied in the quantity of animal and plant foods: vegetarian, semi-vegetarian, and non-vegetarian. The GHGE intensities of 210 foods were calculated through life-cycle assessments and by using published data. The all-cause mortality rates and all-cause mortality HRs for the AHS-2 subjects were adjusted for a range of lifestyle and sociodemographic factors and estimated according to dietary pattern.RESULTS: : With the use of the non-vegetarian diet as a reference, the mean reductions in GHGEs for semi-vegetarian and vegetarian diets were 22% and 29%, respectively. The mortality rates for non-vegetarians, semi-vegetarians, and vegetarians were 6.66, 5.53, and 5.56 deaths per 1000 person-years, respectively. The differences were significant. Compared with non-vegetarians, mortality HRs were lower for semi-vegetarians (0.86) and vegetarians (0.91).CONCLUSIONS: : Moderate differences in the caloric intake of meat products provided nontrivial reductions in GHGEs and improved health outcomes, as shown through the mortality analyses. However, this does not mean that diets lower in GHGEs are healthy.
"S. Soret et al., "Climate change mitigation and health effects of varied dietary patterns in real-life settings throughout North America," American Journal of Clinical Nutrition 100, supplement 1, (June 2004): 490S-495S, http://www.ncbi.nlm.nih.gov/pubmed/24898230.