Relation of Dietary Healthfulness to Food Environmental Impact

Recent discussions in the literature have suggested that reducing the consumption of foods with high associated greenhouse gas (GHG) emissions and impacts on global water resources, such as meat and dairy foods, and replacing them with lower GHG and water resource burden associated foods, such as plant based foods, will help mitigate global cardiovascular disease, diabetes, cancer, and obesity. However, this hypothesis has not been empirically tested. The objective of this dissertation was to examine the correlation between diet-related chronic disease, obesity, and undernourishment, and the GHG emissions and Water Footprints of food. Chapter 1 focused on obesity, and how foods found to be related to weight gain correlate with these food’s GHG emissions. The Spearman correlation between a food’s associated weight gain and GHG emission was 0.12 (95% CI: -0.37, 0.55). These results did not change after the removal of unprocessed red meat from the analysis. Nuts, whole grains, fruits, and vegetables exhibited lower effects on weight gain and CO2e production. Chapter 2 examined diet related NCDs, obesity, life expectancy, and undernutrition, and how country food supply GHG emissions associate with these particular country health outcomes. After adjustment for country socioeconomic and lifestyle characteristics, there was no association between country specific food-related GHG emissions and country specific rate of premature mortality from NCDs (β=0 [95% Confidence Interval (CI): -5, 5] deaths/100,000), life expectancy (β=0.19 [95% CI: -5, 5] years), prevalence of obesity (β=2% [95% CI: -3%, 6%]), or undernourishment (β=-7% [95% CI: -15%, 1%]). Results did not change when the association was examined within strata of GDP per capita. However, there were large variation in country health indicators at every level of GHG emissions, and some countries had both low food-related GHG emissions and favorable health statistics. Chapter 3 evaluated how healthfulness of diet, as measured by the Alternative Health Index, relates to food WF categories within a cohort of US women. Reservoir WF increased linearly whereas rain WF decreased linearly with increasing adherence to the AHEI. Women in the highest quintile of adherence to the AHEI had reservoir WF that was 309 liters/day (95% confidence interval (CI): 290 – 327) higher and a rain WF that was 313 liters/day (95% CI: -333, -294) liters lower than that of women in the lowest quintile of adherence to the AHEI. When both reservoir and rain WF were considered together, women on the highest quintile of adherence to the AHEI had a total WF that was 50 liters/day (95%: -81, -19) lower than that of women in the lowest quintile of adherence. The unfavorable directionality pertaining to reservoir and rain WF with healthier eating scores warrants further research, especially with progressively unequal global freshwater availability. Although overall associations between food GHG and the health outcomes analyzed were not observed, there were variations noted that warrants further examination. However, dietary impacts on global water reservoirs should be simultaneously considered. Hence, efforts that enable the adoption of effective policies to address both dietary quality and the reduction of food GHG emissions simultaneously, without exacerbating undernutrition and water scarcity, should continue