High-Protein Breakfast and Postprandial Glucose Levels

Japan: Compared with the usual breakfast, a high-protein breakfast (when taking lunch) could suppress postprandial glucose (PPG) levels after breakfast, lunch, and dinner, a recent study in the journal Nutrients has revealed. However, a high-protein breakfast failed to suppress postprandial glucose at dinner when lunch was skipped.

"Our findings imply that skipping lunch could attenuate the effect of a high-protein breakfast on suppressing the levels of post-dinner glucose," Keyi Xiao from Waseda University in Shinjuku-ku, Tokyo, Japan, and colleagues wrote in their study.

Postprandial hyperglycemia may raise the risk of many lifestyle-related diseases like hypertension, cardiovascular diseases, and obesity and is a major death cause in patients with type 2 diabetes (T2D). Therefore, identifying ways to reduce postprandial glucose is critical to prevent these lifestyle-related diseases.

Recently, the second meal effect has gained popularity as a strategy for controlling postprandial glucose levels; it is defined as the impact of food intake in one meal on the pp glucose level after the second meal.

Against the above background, the research team aimed to examine the effect of a high-protein breakfast diet with or without lunch on the postprandial glucose level during the day.

For this purpose, the researchers performed a randomized, crossover design that recruited 12 healthy young participants (nine women and three men). In two weeks, four trials were conducted:

• High protein breakfast + skipped lunch
• Normal breakfast + skipped lunch
• High protein breakfast + lunch
• Normal breakfast + lunch

During each trial, lunch, breakfast, and dinner on the trial day and dinner before the trial day was taken as test meals, and the meal timing was fixed. CGM (continuous glucose monitoring) was used during the experiment to assess the blood glucose level. The team calculated the incremental area under the curve (iAUC) of the postprandial glucose level.

The researchers reported the following findings:

• Compared with normal breakfast, a high protein breakfast suppressed the three h iAUC of postprandial glucose level after breakfast and 1.5 h iAUC after lunch.
• A high protein breakfast diet suppressed the dinner and overall day postprandial glucose level during lunch, but no significant difference was observed when skipping lunch.

"A high protein breakfast, when taking lunch, could suppress postprandial glucose levels after breakfast, lunch, and dinner compared with a normal breakfast," the researchers wrote. "However, a high-protein breakfast did not suppress the postprandial glucose level at dinner when skipping lunch."

To conclude, skipping lunch could attenuate the effect of a high-protein breakfast on post-dinner glucose suppression.

Reference

Xiao, K.; Furutani, A.; Sasaki, H.; Takahashi, M.; Shibata, S. Effect of a High Protein Diet at Breakfast on Postprandial Glucose Level at Dinner Time in Healthy Adults. Nutrients 2023, 15, 85. https://doi.org/10.3390/nu15010085