High protein diets enhance glycemic regulation during energy restriction: a comparative analysis of milk‐ and soy‐based diets (823.1)

Abstract

Consuming high protein during energy restriction (ER) promotes glycemic control. However, the extent to which protein source modulates the glycemic response and the intracellular mechanisms by which hepatic regulation of blood glucose is maintained during ER is not well described. Eighty male Sprague‐Dawley rats (12 weeks old) were randomly divided into 8 treatment groups and fed energy adequate (EA) or ER (60% of the ad libitum feed intake for EA) diets containing two levels (control: CP, 10%; and high protein: HP, 35%) and sources (milk protein concentrate: MPC; and low isoflavone soy concentrate: SOY) of protein for 16 weeks. Fasting serum insulin and glucose concentrations were assessed, and hepatic regulators of gluconeogenesis were analyzed using Western blot. Blood glucose was similar across groups (group mean ± SD, 109 ± 11 mg/dL, P > 0.05). However, insulin levels were lower (P < 0.05) for HP (162 ± 63 pmol/L) than CP (208 ± 80 pmol/L); ER (165 ± 65 pmol/L) than EA (204 ± 80 pmol/L); and MPC (160 ± 66 pmol/L) than SOY (208 ± 75 pmol/L). Independent of protein source and energy status, glucose‐6‐phosphatase, phosphoenolpyruvate carboxykinase, and hepatic nuclear factor‐1α total protein content were higher (P < 0.05) for HP than CP. These data confirm the gluconeogenic advantage conferred by consuming a HP diet and suggest that a milk‐based diet may further enhance glycemic control by increasing insulin sensitivity.Grant Funding Source: Supported by Dairy Research Institute and USAMRMC