The Effects of Intake of the Fortified Bread by Whey Protein Concentrate on Glycemic Control, Lipid Profile, Blood Presure, Anthropometric Parameters, Resting Energy Expenditure, Oxidative Stress Markers and Appetite in Women With Type 2 Diabetes Mellitus

Abstract

tract Background & Objectives: Diabetes mellitus (DM) is characterized by protracted high levels of blood glucose and glycemic control is vital for patients with DM. Today, the desire to use natural compounds and traditional medicines has increased. Some dietary factors such as whey protein (WP) have both insulinotropic and glucose-lowering effects in healthy subjects and patients with type 2 diabetes mellitus (T2DM). In order to avoid the prescription of WP powdered supplements and with attention to the bread as a staple food of Iranians, in the present study, we decided to produce whole wheat bread fortified with whey protein concentrate (WPC) to make supplementation with this natural compound, which is useful for DM, in a more practical way and closer to people's lives. Due to the insufficient data on the metabolic consequences of long-term WP consumption, in this trial we aimed to examine the effects of the fortified bread by WPC, on glycemic status, lipid profile, blood pressure, anthropometric parameters, resting energy expenditure (REE), oxidative stress markers, and appetite in overweight/obese women with T2DM. Materials & Methods: First, in order to carry out this trial, a study on the production of the fortified bread by WPC was conducted, and the sensory, physicochemical, and antioxidant characteristics of the bread samples were investigated. Then, in a 12-week double-blind placebo-controlled randomized clinical trial, 48 overweight/obese women with T2DM were randomly allocated into either WPC (bread fortified by 20 g WP concentrate) or placebo (unfortified bread) group. At the pre-and post-intervention phase, physical activity, blood pressure, anthropometric parameters, REE, appetite, serum levels of glucose, insulin, glycosylated hemoglobin A1C (HbA1C), lipid profile, total antioxidant capacity (TAC), malondialdehyde (MDA), and dietary intakes were assessed. The homeostatic model assessment for insulin resistance (HOMA-IR) was used for estimation of insulin resistance. Results: The results of the bread’s tests showed a decreasing trend regarding the appearance and color, texture, overall acceptance, penetration and brightness (L) of bread samples, and also an increasing trend in the case of the chewiness, taste and aroma, antioxidant property, moisture, and redness (a) and yellowness (b) of bread samples, with increasing WPC content. Among the studied parameters, just the changes of the texture, moisture, penetration, and indicators of the surface color, L, a and b, were significant (p= 0.002, p<0.001, p= 0.003, respectively). In the clinical trial phase, 35 patients completed the trial. At the endpoint, there were no significant differences between-group for the assessed glycemic parameters, and only HbA1C was higher in the WPC group after adjusting for the confounders and baseline values (p =0.034). Fasting blood glucose was significantly increased in WPC group (p =0.019). There were significant increases in HOMA-IR (p = 0.001 and p = 0.002, respectively) and serum level of insulin (p = 0.004 and p = 0.001, respectively) in both WPC and placebo groups. There were no significant within- or between-group changes for lipid profile and blood pressure of the patients. At the endpoint, there were no significant differences between-group for anthropometric parameters, except for waist circumference (WC), which was lower in the WPC group after adjusting for the confounders (p = 0.040). Serum level of MDA was significantly decreased in the WPC group (p = 0.022), but there were no significant within- or between-group changes in serum level of TAC, REE, and appetite sensations, the “hunger” was lower in the WPC group after adjusting for the confounders (p = 0.045). Conclusion: According to the results, the prepared bread can be considered an acceptable product in the bread industry, but considering the observed effects on the pattern of glucose, lipids and blood pressure of obese/overweight women with T2DM, adverse effects of its consumption is possible. However, the significant reduction of WC, serum level of MDA and feeling of hunger, after consuming WPC-fortified bread, if confirmed by future related studies, may justify the efficiency of WPC-fortified bread in T2DM patients. Keywords: Whey Proteins, Diabetes Mellitus, Oxidative Stress, Anthropometry, Lipids