Several large observational studies suggest that the amount of dairy products consumed is inversely related to the risk of type 2 diabetes. However, the data are largely inconsistent on whether the reduction in type 2 diabetes risk is greater with the consumption of low-fat or full-fat dairy products, and whether there may be specific benefits associated with the consumption of fermented dairy products (i.e. yogurt or cheese). Importantly, because observational studies can establish only associations, such studies have not been able to provide any insight into whether dairy product consumption actually cause a reduction in type 2 diabetes risk. Even if the effect was causal, the mechanisms through which dairy foods may act to improve glucose tolerance have yet to be elucidated.
The DAIRY Study is a randomized controlled trial aimed at addressing whether the consumption of dairy foods generally improves glucose homeostasis compared to a largely dairy-free diet, and whether low-fat dairy products differ in this regard from full-fat dairy products. Additionally, this study begins to investigate the mechanisms by which dairy-rich diets may affect glucose tolerance and its determinants. We aim to enroll 72 insulin resistant men and women with the metabolic syndrome who consume diets differing in their type and content of dairy foods, in a parallel-design randomized controlled trial. In a 16-week dietary intervention, we will compare the effects of consuming a diet largely free of dairy foods (limited dairy diet) vs. a diet rich in nonfat milk and yogurt and low fat cheese (low-fat dairy diet) vs. a diet rich in full-fat milk, yogurt and cheese (full fat dairy diet) on glucose tolerance and major determinants of oral glucose tolerance. We will also assess the impact of the intervention diets on energy balance and a wide range of risk factors for cardiometabolic disease.
Status: In progress (as of April 2016), completion expected by 2018