Dairy Products and Cardiometabolic Health Outcomes

Abstract

The association between dairy fat intake and type 2 diabetes (T2D) risk remains unclear despite evidence from several studies examining the relationship between dairy product consumption stratified by fat content and risk of T2D. In chapter 1, we investigated the association between dairy fat intake and risk of T2D in the Nurses’ Health Study (NHS), NHSII, and the Health Professionals Follow-Up Study (HPFS) with emphasis on modeling isocaloric replacements of dairy fat with other macronutrients. Dairy fat was not associated with risk of T2D when compared with calories from carbohydrate. However, replacing 5% of calories from dairy fat with the equivalent energy from other sources of animal fat or carbohydrate from refined grains was associated with a 14% and a 4% increased risk of T2D, respectively. Conversely, a 5% calorie substitution of carbohydrate from whole grains was associated with 7% lower risk of T2D. T2D is an established risk factor of cardiovascular disease (CVD) but there is sparse evidence to support dietary recommendations for T2D patients. In chapter 2, we examined the association between total dairy and individual dairy product consumption and risk of CVD among participants with T2D in the NHS and HPFS. Intake of total dairy product or individual dairy products were not associated with CVD risk, with the exception of an inverse association between ice-cream intake and CVD health outcomes. In substitution analyses, replacing one serving of dairy products with red meat or processed red meat was associated with a 6% and 13 increase in CVD risk, respectively. Conversely, replacing one serving of total dairy products with one serving of nuts was associated with a 12% risk reduction of CVD. In chapter 3, we examined the association between very-long chain saturated fatty acids (VLCSFAs), such as 20:0, 22:0, and 24:0 and risk of T2D in participants from the NHS and HPFS who previously provided blood samples. Comparing extreme quartiles of plasma levels, 20:0, 22:0, 24:0, and their sum were associated with 50%, 58%, 60%, and 60% lower T2D risk, respectively. Only erythrocyte biomarkers of 20:0 and 22:0 fatty acids were inversely associated with T2D risk.