Drinking Milk with Breakfast is a Good Strategy for Glucose Management
One of the earliest changes in the development of type 2 diabetes is the loss of early postprandial insulin response, a change which contributes to postprandial hyperglycemia. Eating foods that can boost the early postprandial insulin response is an important glucose-lowering strategy in treating type 2 diabetes. High protein diet that contains 30-40% of caloric intake as protein had been suggested as a good dietary strategy for glucose management. Among various protein sources, whey protein had been found very effective in lowering glucose (1).
The effect of common dietary sources of animal or vegetable proteins on concentrations of postprandial blood glucose, insulin, and amino acids were tested in 12 healthy subjects (6 men and 6 women, aged 20 –28 years old) (1). These volunteers were served test meals consisting of milk, cheese, whey, cod, and wheat gluten with equivalent amounts of lactose. An equal carbohydrate load of white-wheat bread was used as a reference meal. All meals contained 25 g carbohydrate and 18.2 g protein, except the gluten low and white-wheat-bread reference, which contained 25 g carbohydrate and 2.8 g protein. Whey proteins and dried skimmed milk were tested as a drink, whereas casein was given in the form of cheese.
A correlation was found between postprandial insulin responses and early increments in plasma amino acids; the strongest correlations were seen for leucine, valine, lysine, and isoleucine. Milk powder and whey had substantially lower postprandial glucose areas under the curve (AUC) than did the bread reference (lowered 62% and 57%, respectively) during the 90 minutes time period after the meal. Whey meal was accompanied by higher insulin secretion (AUC of insulin secretion increased 90%). This study showed that food proteins differed in their capacity to stimulate insulin release. Milk proteins had insulinotropic properties; the whey fraction of the milk had the predominating insulin secretion stimulation effect (2).
Twelve healthy volunteers at ages 20-30 years old were provided 3 whey protein drinks, containing 4.5, 9 or 18 g protein as breakfast meals in random order. All meals contained 25 g available carbohydrates (glucose). The same amount of glucose in water was used as reference. The test drinks were provided as breakfasts on four different occasions in random order with approximately 1 week between each test. Compared with the reference meal, all 3 whey doses (4.5, 9 and 18 g) reduced the glycemic response (AUC 0–120 min, lowered 25%, 37% and 46%, respectively). The 18 g dose significantly increased the insulin response (AUC 0–120 min, increased 64%). Whey protein affected glucose, insulin and plasma amino acids levels to a glucose load in a dose-dependent manner. Even comparatively low doses of whey protein, such as 9 g, could reduce postprandial glycemia significantly when added to a carbohydrate-rich meal (3).
Since whey proteins have been shown to have insulinotropic effects (stimulating or affecting the production and activity of insulin) and reduce the postprandial glucose level in healthy subjects (1), scientists would like to study whether whey protein has such effects in people with diabetes. Fourteen diet-treated subjects with type 2 diabetes were served a high glycemic index breakfast (white bread) and subsequent high glycemic index lunch (mashed potatoes with meatballs). The breakfast and lunch meals were supplemented with whey on one day; whey was exchanged for lean ham and lactose on another day. Blood samples were analyzed before and during 4 hours after breakfast and 3 hours after lunch for the measurement of blood glucose and insulin. The insulin responses were higher after both breakfast (increased 31%) and lunch (increased 57%) when whey was included in the meal than when whey was not included. After lunch, the blood glucose response was significantly reduced at 2 hour after whey ingestion (AUC 0-120 minutes, decreased 21%). Addition of whey to meals with rapidly digested and absorbed carbohydrates stimulated insulin release and reduced postprandial blood glucose increase after a lunch meal consisting of mashed potatoes and meatballs in type 2 diabetic subjects (4).
In a randomized, open-label crossover clinical trial, a group of scientists studied 15 volunteers with well-controlled type-2 diabetes who were not taking any other medications except for sulfonylurea or metformin. These participants consumed, on two separate days, either 50 g whey dissolved in 250 ml water or placebo (250 ml water) followed by a standardized high-glycemic-index breakfast in a hospital setting. The results showed that over the whole 180 min post-meal period, glucose levels were reduced by 28% after whey was given prior to the meal with reductions during both early and late phases. The responses of insulin and C-peptide were both significantly increased (105% and 43% higher, respectively) with whey given prior to the meal compared with those of placebo. Notably, the early insulin response was 96% higher after whey. Whey protein was suggested to be an effective dietary strategy for lowering glucose in type-2 diabetes (5).
Studies showed that addition of whey protein at breakfast had a glucose-lowering effect through increased insulin secretion. However, whether this is a long-term effect in Type 2 diabetes needs to be studied. Fifty-six Type 2 diabetes participants (aged 58.9±4.5 years old) were randomized to one of 3 isocaloric diets with similar lunch and dinner, but different breakfast: 1) 42 g total protein, 28 g whey (n=19); 2) 42 g various protein sources (n=19); or 3) high-carbohydrate breakfast, 17 g protein from various sources (n=18). Body weight and HbA1C were examined after 12 weeks. After 12 weeks, the participants underwent meal tests for postprandial glycemia, insulin, C-peptide, and hunger and satiety scores. Overall postprandial glucose AUC was significantly reduced by 12% in high various protein diet and by 19% in high whey protein diet, compared with that of high carbohydrate diet. Compared with high various protein diet and high carbohydrate diet, high whey protein diet led to a significantly greater postprandial overall AUC for insulin, C-peptide, and satiety scores, while hunger scores were reduced. After 12 weeks, HbA1C was significantly reduced after high whey diet, high various protein diet and high carbohydrate diet were 0.89±0.05%, 0.6±0.04% and 0.36±0.04%, respectively. Furthermore, the participants lost body weight, the weight loss with high whey diet, high various protein diet and high carbohydrate diet were 7.6±0.3 kg, 6.1±0.3 kg and 3.5±0.3 kg, respectively. Adding whey protein to the breakfast is an important dietary strategy in the long-term management of Type 2 diabetes (6).
If you absolutely cannot get whey by drinking whey-containing cow milk due to lactose intolerance as many Asian people do, there is alternative, soy milk. Soy milk has similar glucose-lowering benefit as dairy milk but via different mechanisms. Sun et al. studied 12 healthy Chinese men (aged 21–26 years old) in a randomized, cross-over study with three experimental trials separated by a 1-week to minimize carry-over effects. Subjects were given three different meals in random order. All meals contained 50 g of available carbohydrate. The reference meals consisted of white bread (91 g) and water (322 ml). The test meals consisted of white bread (58 g) and isovolumetric amounts of either chilled soy milk or low-fat cows’ milk (322 ml) containing approximately 12 g of soy protein or milk protein. Consumption of both soy and cows’ milk with carbohydrates induced a similar reduction in glycemic response through a different mechanism, beyond insulin action. Glucose-dependent insulinotropic polypeptide concentrations increased to significantly greater levels after soy milk consumption (AUC 60 % higher) compared with cows’ milk and control (7).
Adding protein, such as drinking cow milk or soy milk with your breakfast is a good strategy for glucose management. If you are interested in learning additional information about effects of whey protein, or alternative protein such as soy protein on glycemic control, or different healthy foods on glucose management, check out other pages on this website, and feel free to contact us to ask any Questions about Healthy Foods for Glucose Management and Diabetes Prevention.
References:
1. Beaudry MK, Devries CM. Nutritional Strategies to Combat Type 2 Diabetes in Aging Adults: The Importance of Protein. Front Nutr. 2019; 6: 138.
2. Nilsson M, Stenberg M, Frid AH, Holst JJ, Björck IM. Glycemia and insulinemia in healthy subjects after lactose-equivalent meals of milk and other food proteins: the role of plasma amino acids and incretins. Am J Clin Nutr. 2004; 80(5):1246-53.
3.Gunnerud UJ, Ostman EM, Björck IM. Effects of whey proteins on glycaemia and insulinaemia to an oral glucose load in healthy adults; a dose-response study. Eur J Clin Nutr. 2013; 67(7):749-53.
4.Frid AH, Nilsson M, Holst JJ, Björck IM. Effect of whey on blood glucose and insulin responses to composite breakfast and lunch meals in type 2 diabetic subjects. Am J Clin Nutr. 2005; 82(1):69-75.
5. Jakubowicz D, Froy O, Ahrén B, Boaz M, Landau Z, Bar-Dayan Y, Ganz T, Barnea M, Wainstein J. Incretin, insulinotropic and glucose-lowering effects of whey protein pre-load in type 2 diabetes: a randomised clinical trial. Diabetologia. 2014; 57(9):1807-11.
6. Jakubowicz D, Wainstein J, Landau Z, Ahren B, Barnea M, Bar-Dayan Y, Froy O. High-energy breakfast based on whey protein reduces body weight, postprandial glycemia and HbA1C in Type 2 diabetes. J Nutr Biochem. 2017; 49:1-7.
7. Sun L, Tan KW, Siow PC, Henry CJ. Soya milk exerts different effects on plasma amino acid responses and incretin hormone secretion compared with cows' milk in healthy, young men. Br J Nutr. 2016; 116(7):1216-1221.