Effects of protein on glycemic and incretin responses and gastric emptying after oral glucose in healthy subjects

Abstract

Background: Dietary interventions represent a promising therapeutic strategy to optimize postprandial glycemia. The addition of protein to oral glucose has been reported to improve the glycemic profile. Objective: The aim of the current study was to evaluate the mechanisms by which protein supplementation lowers the blood glucose response to oral glucose. Design: Nine healthy men were studied on 3 d each in a random order. Subjects consumed 300-mL drinks containing either 50 g glucose (Glucose), 30 g gelatin (Protein), or 50 g glucose with 30 g gelatin (Glucose ѿ Protein) in water labeled with 150 mg [13 C]acetate. Blood and breath samples were subsequently collected for 3 h to measure blood glucose and plasma insulin, glucagon-like peptide 1 (GLP-1), and glucose-dependent insulinotropic polypeptide (GIP) concentrations and gastric half-emptying time, which was calculated from 13 CO 2 excretion. Results: The blood glucose response was less after Glucose ѿ Protein than after Glucose (P 0.005); GIP was lower (P 0.005), and there were no significant differences in plasma insulin or GLP-1. Protein alone stimulated insulin, GLP-1, and GIP (P 0.05 for each) without elevating blood glucose. The gastric half-emptying time was greater after Glucose ѿ Protein than after Glucose (P 0.05) and tended to be greater for Glucose than for Protein (P ҃ 0.06). Conclusions: In healthy humans, the addition of protein to oral glucose lowers postprandial blood glucose concentrations acutely, predominantly by slowing gastric emptying, although protein also stimulates incretin hormones and non-glucose-dependent insulin release.Am J Clin Nutr 2007;86:1364 -8.

Effect of drinking compared with eating sugars or whey protein on short-term appetite and food intake

“…23 Second, gelatin alone, whether in liquid or solid form, had no effect on average appetite scores or FI compared with the water control, its addition to sugar or whey protein. Finally, gelatin addition had no detectable effect on blood glucose (Table 4), as previously shown in even higher doses, 30 further supporting its use as a vehicle for these comparisons. Power analyses, with a-level of 0.05 and the power of 0.8, from experiments 2 and 3 suggest that a sample size of 5000 and 168 subjects would be required to detect a significant difference between solid and liquid forms of sugars and whey protein, respectively.…”

“…[34][35][36] However, no differences in the effect of the source were found, suggesting that the presence or absence of GMP in whey preloads did not influence the effect of whey protein on satiety or FI at a test meal in agreement with previous reports. 37,38 Blood glucose concentrations were measured because they associate with satiety and food intake 1 and may have been affected by an insulinotropic effect of gelatin, 30 or by different absorption rates of the liquid and solid sugars, thus confounding interpretation of results. However, treatments of gelatin or the disaccharide sucrose and its monosaccharide equivalent of G50:F50 in both liquid and solid forms did not Form of sugar and whey and food intake T Akhavan et al differentially influence blood glucose (Table 4), except at 15 min when the liquid G50:F50 mixture led to a higher blood glucose than did solid sucrose.…”

Effects of lupin-enriched foods on body composition and cardiovascular disease risk factors: a 12-month randomized controlled weight loss trial

“…42 In the present study the difference in fibre intake at 12 months was 14 g per day and the difference in HOMA score was 0.7 units. Acutely, dietary protein enhances insulin secretion, 43,44 leading to increased glucose disposal. Although data from epidemiological studies indicate that this may not result in improved insulin sensitivity, 45,46 positive effects of higher protein intakes have been observed in some intervention studies.…”

Use of the glycemic index in nutrition education

“…Proteins reduce postprandial blood glucose level by slowing gastric emptying and stimulating the secretion of incretins and of insulin 20 . On the other hand, fat tends to reduce blood glucose response because they reduce gastric emptying rate 21 .…”

“…Given the above, the inclusion of high protein foods, such as milk and dairy products, lean meats, gelatin, egg whites and legumes, can be an interesting strategy for controlling the impact of carbohydrate foods on postprandial blood glucose level 20,23,24 . Similarly, the inclusion of high-fat foods, such as nuts and peanuts, in high-carbohydrate meals, and the of oils that are good source of polyunsaturated and monounsaturated fatty acids, such as olive oil, to high-GI foods, such as potatoes (GI=78±4) or manioc (GI=94±11), may be healthy alternatives for reducing their GIs.…”