Abstract Body (Do not enter title and authors here): Inflammation is vital to maintaining homeostasis and immune defense, yet chronic, low-grade inflammation is a hallmark of many cardiometabolic diseases. Due to the high saturated fatty acid content in full-fat dairy foods, national dietary guidance recommends consuming low- or non-fat dairy foods to decrease cardiometabolic disease risk. However, many unique fatty acids found in dairy fat may elicit beneficial effects on chronic low-grade inflammation and the effect of dairy fat within its food matrix remains unclear. Thus, our research question centered on the effect of full-fat dairy foods on inflammatory tone. We hypothesized that short-term consumption of three daily servings of full-fat yogurt would beneficially affect inflammatory tone. The aim of the project was to compare the inflammatory response of individuals with prediabetes after a diet with and without dairy fat. An eight-week randomized controlled clinical trial was conducted comprising two, three-week experimental diet periods, differentiated by the daily consumption of either full-fat yogurt (3.25% fat) or non-fat yogurt. Each experimental diet was preceded by a one-week control diet. Following each diet period, peripheral blood mononuclear cells were isolated from whole blood and incubated in media with or without lipopolysaccharide stimulus. After a 24-hour incubation, cell supernatants were analyzed for interleukin (IL)-1β, IL-6, IL-8, IL-10, and tumor necrosis factor-α concentrations. Under unstimulated conditions, the concentration of IL-1β present in the cell supernatant was lower as a result of the full-fat yogurt diet, compared to the non-fat yogurt diet (0.1 pg/mL compared to 24 pg/mL, respectively; P < 0.01), but there were no differences between diets in IL-1β concentrations at 1, 10, or 100 ng/mL lipopolysaccharide stimulation. Diet did not affect supernatant concentrations of IL-6, IL-8, IL-10, or tumor necrosis factor-α in the unstimulated and stimulated conditions. In conclusion, only minimal differences were observed between diets with three daily servings of full-fat or non-fat yogurt indicating that short-term consumption of dairy fat may not impact inflammation via peripheral blood mononuclear cell cytokine secretion.

Funding for this project was provided by the National Dairy Council, Vermont Dairy Promotion Board, USDA National Institute of Food and Agriculture, and UVM Food Systems Research Center.