The Nexus of Planetary and Human Health: Exploring the Effects of a Planetary Health Diet on Cardiometabolic Risk Outcomes in South Asians Living in America

Abstract

The modern global food system, responsible for ~30% of the total global greenhouse gas emission, is a major contributor to climate change and is exerting significant influence on both human and environmental health. Recognizing the imperative to address the accelerated impacts of anthropogenic climate change while ensuring sustainable production and consumption practices, the EAT-Lancet Commission proposed a Planetary Health reference Diet in 2019. This dietary pattern is based on a diverse range of whole plant-based foods, including fruits, vegetables, legumes, nuts, and whole grains, and encourages reduced consumption of red and processed meats, added sugars, and refined grains. Poor diet is among the top risk factors for cardiometabolic disease (CMD), which disproportionately burdens South Asian populations. Studies indicate that South Asian Americans, comprising 4%-5% of the total US population, and while genetics and family history play roles in increased cardiometabolic risk factors among South Asians, the interplay of sociocultural factors and dietary shifts towards a more westernized diet in the context of South Asians living in America underscores their disproportionate vulnerability. Given this context, this dissertation endeavored to explore the effects of a Planetary Health Diet on cardiometabolic risk outcomes in South Asians Living in America. The reference diet proposed by the 2019 EAT-Lancet Commission is associated with significant health benefits, including a substantial decrease in overall mortality; however, there is a lack of evidence and a standardized metric to quantify the health outcomes, diet quality, and environmental advantages of adhering to a planetary-conscious diet. Thus, using data from the longitudinal Mediators of Atherosclerosis in South Asians Living in America (MASALA) study, Chapter One we developed and validated a Planetary Health Diet Index (PHDI) that measures adherence to the EAT-Lancet reference diet. In Chapter Two, we delve into the predictive criteria of this index by examining the associations of the PHDI with cardiometabolic risk markers and disease outcomes in the MASALA cohort. Finally, in Chapter Three, we employ a systems epidemiology approach to identify and validate plasma metabolomic profiles associated with the Planetary Health diet and evaluate associations of the derived metabolomic profile with cardiometabolic risk in South Asian Americans.