DEPARTMENT OF AGRICULTURAL, FOOD AND NUTRITIONAL SCIENCE
PhD Thesis Seminar
|Supervisors:||Dr. Spencer Proctor, Dr. Caroline Richard|
|Date:||Wednesday, December 14, 2022|
|Location:||5-112 Li Ka Shing Centre (LKS)
|Title:||Effect of Consuming Dairy Fats on Obesity-Related Cardiometabolic Perturbations and Immune Function in Low Birthweight Swine|
Although dairy intake has been shown to have a neutral or some beneficial effect on major cardiometabolic risk factors, the impact of dairy, and especially dairy fat, on immune function remains to be investigated. To understand the effect of consuming dairy fat on cardiometabolic risk factors and immune function, we used an established low birthweight (LBW) swine model of diet-induced insulin resistance to compare high-fat and low-fat dairy products to a control high-fat diet (CHF). LBW piglets were randomized to consume one of the 3 experimental diets: 1) CHF, 2) CHF diet supplemented with 3 servings/day of high-fat dairy (HFDairy) and 3) CHF diet supplemented with 3 servings/day of low-fat dairy (LFDairy). As comparison groups, normal birthweight (NBW) piglets were fed a CHF (NBW-CHF) or standard pig grower diet (NBW-Chow). At 11 weeks of age, all piglets underwent an established modified oral glucose and fat tolerance test (MOGTT). At 12 weeks of age, piglets were euthanized. Fasting blood and tissue samples were collected. Ex vivo cytokine production by peripheral blood mononuclear cells (PBMCs) and isolated intestinal mesenteric lymph node (MLN) cells stimulated with mitogens were assessed. As expected, LBW-CHF piglets showed early signs of insulin resistance. Feeding high-fat dairy products improved (lowered) fasting plasma glucose concentrations more than low-fat dairy compared to LBW-CHF. Irrespective of fat content, dairy consumption had neutral effect on major cardiometabolic risk factors in both fasting and postprandial state. Following ex vivo mitogenic stimulation on PBMCs and MLN cells, we have for the first time confirmed that LBW-CHF piglets exhibited both impaired peripheral and intestinal immune function particularly T cell function. While feeding high-fat dairy had relative minor effect, feeding low-fat dairy significantly improved the production of IL-2, TNF-α and/or IFN-γ from PBMCs and MLN cells respectively, suggesting improved peripheral and intestinal immune function. Overall, the research presented in this thesis has provided new mechanistic insight to support the role of dairy products, specifically milk, yogurt, and cheese, in counteracting some of the obesity-related cardiometabolic and immune perturbations.