Poster Topical Area: Energy and Macronutrient Metabolism
Location: Hall D
Poster Board Number: 463
Objectives: Observational studies have identified a positive role of dairy fat in the prevention of type 2 diabetes. The principal component(s) responsible are yet to be determined. We hypothesized that unique fatty acids (FA) found in dairy fat per se and derived from rumen microbial synthesis would alter glucose homeostasis, and be protective with respect to glucose intolerance.
Methods: We conducted a clinical trial with 21 healthy adults (10 women, mean ± SEM, body mass index, BMI: 21.3 ± 0.7 kg/m2; 11 men, BMI: 23.8 ± 0.9 kg/m2). A double-masked, randomized crossover design was employed with two sequential 3-wk dietary interventions preceded by a 1-wk run-in period (reflecting a representative U.S. diet) to compare a eucaloric balanced DASH-style diet containing either three daily servings of whole yogurt (dairy fat diet; DF) or fat-free yogurt supplemented with a control fat (control diet). At the end of each a period, the FA composition of serum phospholipids was assessed, and a frequently sampled intravenous glucose tolerance test was performed to quantify the effects of diet on glucose uptake, insulin secretion, and insulin sensitivity.
Results: The FA composition of serum phospholipids, a marker of dietary compliance and intake, reflected the FA composition of the respective diet. During the DF diet, there was a higher content of branched-chain FAs, total trans-18:1, 18:1 t11 (vaccenic acid), and 18:2 c9,t11(rumenic acid) in serum phospholipids (P < 0.001). Consumption of three daily servings of whole yogurt (DF) resulted in a 26% higher glucose effectiveness (SG; index of insulin independent glucose uptake; P = 0.014) and a borderline higher (12%) acute insulin response to glucose (AIRG; index reflecting ß-cell sensitivity to glucose; P = 0.053).
Conclusions: Regular intake of dairy fat promotes improved glucose tolerance by stimulating both insulin-independent glucose uptake and enhanced insulin secretion. Our results bring to light that even modest intake of dairy fat may be necessary to maintain normal glucose homeostasis.
The University of Vermont