Doctoral Dissertation Improvement - The Health Implications of Periodic Dietary Restrictions on Animal Products among Orthodox Christians in the United States

目前，关于现代动物性食品和植物性食品在人类健康和疾病中的作用存在着相互矛盾的观点。人类学理论表明，肉类和动物脂肪在能量密集型人类特征的进化中发挥了关键作用，向以谷物为基础的农业饮食的转变对健康和长寿有害。相反，营养流行病学领域的先进观点表明，肉类和动物脂肪的消费往往与慢性病风险增加有关，而植物性饮食似乎具有保护作用。为了解决这一争论，本项目将探讨饮食限制对动物产品的健康影响，并评估健康指标的变化是否与限制之前食用的动物性食品（如加工肉类与未加工肉类）的数量和质量、作为热量替代品食用的植物性食品（如精制谷物、全谷物、蔬菜和豆类）的类型以及能量平衡的变化有关。正如杂食性饮食对健康的影响可能取决于特定动物和植物性产品的总热量摄入和营养成分一样，植物性饮食对健康的益处可能取决于与加工谷物产品和糖相关的全谷物、豆类、水果和蔬菜的摄入量。更清楚地了解这些相互作用对公共卫生、人类学、营养流行病学和人口健康科学家至关重要。在这些领域分享项目成果有可能影响营养指导在学校的教学和向公众传达的方式，并更广泛地为全球和地方的努力提供信息，以了解和解决美国和全世界与营养有关的慢性疾病日益增长的健康和经济负担。本项目将通过对美国东正教徒（OCs）在大斋节（复活节前的一段时间）进行的为期八周的仪式化的自愿饮食限制来探索这些细微差别。因为OCs收到了关于在大斋节期间不吃哪种动物性食物的指导，但没有关于食用哪种植物性食物作为热量替代品的指导，因此本研究背景允许研究人员探索工业化背景下植物性饮食的自然变化如何改变其对生理健康的影响，以及这种变化如何与动物产品限制的影响共同变化。一组在美国出生的OCs将在他们的四旬斋期间和之前的八周内接受教会指导的最低限度的饮食限制。遵循和不遵循OC四旬斋饮食传统的个人都将被招募参加这项研究。将收集详细的饮食数据、生活方式信息以及心血管和代谢疾病风险的共同标志物，以比较两个时间点的健康指标，并将健康指标的任何变化与特定植物性和动物性食物的变化程度联系起来。这些数据将有助于回答以下问题：从饮食中限制动物产品是否一定会带来健康益处，以及任何可衡量的健康益处在多大程度上取决于构成基线和限制饮食的食物的数量和类型。

Currently there exist conflicting views about the role of modern animal- and plant-based foods in human health and disease. Anthropological theories suggest meat and animal fat played critical roles in the evolution of energy-intensive human traits and that transitions to grain-based agricultural diets were detrimental to health and longevity. In contrast, perspectives advanced in the field of nutritional epidemiology suggest that consumption of meat and animal fat tend to be associated with increased risk of chronic diseases while plant-based diets appear to be protective. To address this debate, this project will explore the health effects of dietary restrictions on animal products and assess whether any shifts in health indicators vary in relation to the amount and quality of animal-based foods (e.g., processed versus unprocessed meats) consumed prior to restriction, the types of plant-based foods (e.g., refined versus whole grains versus vegetables and legumes) consumed as caloric replacements, and shifts in energy balance. Just as the health effects of omnivorous diets may depend on the overall caloric intake and nutritional composition of specific animal- and plant-based products, the health benefits of plant-based diets may depend on the amount of whole grains, legumes, fruits, and vegetables consumed in relation to processed grain products and sugars. A clearer understanding of these interactions is of key interest to public health, anthropological, nutritional epidemiology, and population health scientists. Sharing the project results across these fields has the potential to influence how nutritional guidance is taught in schools and communicated to the public, as well as more broadly inform global and local efforts to understand and tackle the growing health and economic burden of nutrition-related chronic diseases in the U.S. and worldwide. This project will explore these nuances through the study of a ritualized eight-week voluntary dietary restriction on animal products practiced by Orthodox Christians (OCs) in the U.S. during Lent, the period prior to Easter. Because OCs receive guidance on which animal-based foods to abstain from during Lent but not on which plant-based foods to consume as caloric replacements, this study context allows the researchers to explore how natural variations in plant-based diets within industrialized contexts alter their influence on physiological health and how this co-varies with the effects of animal product restriction. A group of U.S.-born OCs will be followed through their Lenten period and a prior eight-week period of minimal church-guided dietary restrictions. Both individuals who do and do not follow the OC Lenten dietary traditions will be recruited for this study. Detailed dietary data, lifestyle information, and common markers of cardiovascular and metabolic disease risk will be collected to compare health indicators across the two time-points and relate any changes in health indicators to the degree of shifts in specific plant- and animal-based foods. These data will help answer the questions of whether restricting animal products from the diet necessarily confers a health benefit and to what degree any measureable health benefits might be contingent upon the amount and types of foods that comprise the baseline and restricted diets.