Date of Award:

8-2026

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Nutrition, Dietetics, and Food Sciences

Committee Chair(s)

Stephan van Vliet

Committee

Stephan van Vliet

Committee

Heidi Wengreen

Committee

Carrie Durward

Committee

Korry Hintze

Committee

Kara J. Thornton-Kurth

Abstract

The question at the center of this dissertation is simple: does the way food is produced change the quality of the food itself in ways that matter for human health? Across a series of studies on bison meat, eggs, and human dietary intervention, the answer was yes. This work began with a broad look at the modern food system and the nutritional consequences of industrialized diets. In particular, it focused on the growing imbalance between omega-6 and omega-3 fatty acids in the Western diet. This balance matters because omega-3 fats support heart, brain, and immune health, and diets high in omega-6 but low in omega-3 have been linked to greater risk of chronic disease. That imbalance is shaped not only by what people choose to eat, but also by how food is grown, how animals are fed, and how agricultural systems prioritize cost, yield, and convenience over nutrient density.

One part of the dissertation examined bison raised in seven finishing systems, from diverse native rangeland to grain-based pen systems. The differences in the meat were striking. Bison raised on forage-rich pasture produced meat with a more favorable fatty acid profile, including lower omega-6:omega-3 ratios and higher concentrations of several omega-3 fatty acids. The meat also carried a different metabolomic signature, including compounds associated with plant-rich diets and forage exposure. In short, feeding system was not just a background detail. It left a measurable mark on the food. Another chapter asked whether geography itself leaves a trace in meat. Bison from four ranches in Kansas, the Nebraska-South Dakota border region, and two Montana sites differed in fatty acids, minerals, and metabolites. Those differences point to a kind of nutritional terroir: a signal shaped by local ecology, including soils, climate, and vegetation. The results suggest that “place” is not just a label on a map. It can become part of the biology of the food.

The final study brought the question into people. In a 16-week randomized controlled trial, healthy adults consumed either pasture-raised or conventionally raised beef, pork, chicken, and eggs. Participants eating the pasture-raised foods showed higher red blood cell omega-3 levels and lower omega-6:omega-3 ratios by the end of the study. The pasture-raised foods contained more omega-3 fatty acids, and these differences were reflected in the participants’ blood.

Taken together, these studies suggest that agricultural systems shape more than productivity or environmental outcomes. They also shape the nutritional quality of food in ways that can carry through to human biology. That makes production ecology a public health question as much as an agricultural one.

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