Abstract
BACKGROUND: Low- and non-fat dairy foods have long been recommended over full-fat dairy foods due to the negative effect of saturated fatty acids on blood lipids. Recent research, however, suggests saturated fatty acids from dairy foods may not impart these negative health effects. Our objective was to evaluate changes in blood lipids following a diet with full-fat (3.25%) yogurt compared with a diet with non-fat yogurt. METHODS: A randomized, double-masked crossover controlled-feeding trial was performed. Participants with prediabetes (n = 13, 7 female and 6 male participants) consumed three daily servings of full-fat or non-fat yogurt for the three weeks of each experimental diet. A one-week run-in diet preceded each experimental diet period. After each experimental diet period and the first run-in diet period, fasting blood and blood drawn at four post-prandial time points during a mixed meal tolerance test were analyzed for lipoprotein concentrations and contents (i.e., the lipid fractions within the lipoproteins). Statistical analyses were performed using linear mixed models, with values from the first run-in diet as the covariate. RESULTS: Fasting blood triacylglycerol concentrations were 10% lower in response to the full-fat yogurt diet, compared with the non-fat yogurt diet (P < 0.01). While no diet-induced differences were observed in lipoprotein subclass concentrations, the triacylglycerol contents of smaller very low-density, intermediate-density, and low-density lipoproteins were lower in response to the full-fat yogurt diet (P ≤ 0.01). Trends indicated potentially greater high-density lipoprotein cholesterol concentrations and high-density lipoprotein size following the full-fat yogurt diet (P ≤ 0.05). The ratio of triacylglycerols: high-density lipoprotein cholesterol concentrations was 17% lower following the full-fat yogurt diet (P < 0.01). CONCLUSIONS: This exploratory analysis demonstrates that short-term full-fat yogurt consumption elicits beneficial effects on the blood lipid profile in individuals with prediabetes and highlights the need for further evaluation of the contribution of dairy fat in yogurt and other dairy food matrices in lipid homeostasis and metabolic health. TRIAL REGISTRATION: This trial is registered at clinicaltrials.gov (NCT03577119).