Effect of Protein, Fat, and Both Protein and Fat on the Glycemic Response of a High Glycemic Index Meal

Research Focus: Elevated blood glucose (BG) levels from a diet high in refined carbohydrates, even in the absence of diabetes, may increase the risk for chronic diseases including cardiovascular disease, type 2 diabetes, and obesity. The purpose of this study was to determine if supplementation of a high glycemic load breakfast with protein, fat, or a combination of the two attenuates the glycemic response in non-diabetic subjects. Research Methods: Thirteen healthy adults, age 24.7±4y, BMI 25.1±4.5 completed four trials, having fasted 8-12h for this randomized, double-blind crossover study. Fasting BG was measured, then subjects consumed 2 slices of white bread and 250mL of apple juice (60g carbohydrate) alone (control), or with an added protein (100kcal egg white), fat (100kcal butter), or protein+fat (50kcal egg white and 50kcal butter) within 15min, then repeated BG measurement at 15, 30, 60, 90, and 120min after baseline. ANOVA indicated that there was a difference in the time that BG peaked among the groups. Tukey’s post-hoc analysis indicated that BG peaked earlier for the added protein group compared to the added fat group (P=0.007). Research Results/Findings: The spike was not significantly different between the control and the treatments, and there were no differences in BG at the time points measured between the control and the treatments. The spike in BG (peak minus baseline) was significantly lower with added fat compared to added protein group (69.0±15.4 vs 46.9±13.0, respectively, P Conclusions from Research: The results of this study indicate that added protein in the form of egg white, added fat in the form of butter, and added protein and fat in the form of egg white and butter in an amount that adds 100 kcal does not attenuate the spike or overall glycemic response to an HGI meal. Added protein in the form of egg white results in a greater spike in BG compared to butter which could be from glucogenic amino acids in egg white. For this study, neither added protein or fat (or the combination of the two) blunted the glycemic response. This may be because the amount of added protein and fat used in this study was not adequate to result in a response. Additional research should be conducted to determine the types and amounts of added protein that are most effective in attenuating the glycemic response to an HGI meal