T2D is characterised by postprandial glucose responses (PPGR) with patients generally reliant on invasive medication to control responses. However, results from new research into nutritional supplements propose a more natural, holistic approach.
Two cross-over studies carried out in Switzerland and published in Nutrients, show that pre-meal consumption of 10g of whey protein microgel (WPM) can reduce PPGR by up to 30%; risk factors for T2D were also mitigated after consumption of 250mg of mulberry (Morus alba) leaf extract alongside a 510kcal meal in study participants.
PPGR is the main contributor to total glucose fluctuations in individuals with T2D or prediabetes and controlling responses may help reduce cases among overweight and obese patients as well as in other at-risk groups, according to the study authors.
“Prediabetes is rapidly increasing worldwide and is not only associated with body mass index (BMI) but also with age, prevention should also start with healthy and lean people.”
Glycaemic episodes are often triggered by carbohydrate-rich meals and managing PPGS through macronutrient intake is key to preventing hyperglycaemia and cardiometabolic diseases.
The authors explain: “The macronutrient composition of a meal, and especially its quantity and quality of carbohydrates (CHO), are the main drivers of PPGR rise. Yet, nutritional supplements have been reported to lower the PPGR of CHO-rich meals independently of a change in their macronutrient content.”
The mediating effects of whey protein consumed by T2D patients up to 30 minutes before a meal is well-documented. Findings suggest protein aggregates in WPM delay amino acid absorption and favour pre-meal efficacy of PPGR.
Other studies on lean and healthy subjects taking a low dose of whey protein isolate (10g) reveal the supplement promoted lower glucose responses “by delaying gastric emptying without stimulating insulin secretion”.
This mechanism is specific to pre-meal administration but the potential impact of timing of consumption or the effect of different forms of whey protein on lowering PPGR is under reported, the authors write.
Similarly, studies have consistently observed the benefit of mulberry leaf extract on lowering PPGR by inhibiting glucose absorption after carbohydrate consumption.
The aim of the randomised studies was to identify optimal conditions to improve efficacy of the supplements in reducing the glycaemic response. Nine interventions were investigated with variations in the active compound of the supplement and timing of administration.
Three supplements were analysed and compared to the control (pure water). The supplements comprised a WPI drink reconstituted with 100ml of water; a WPM drink containing 100ml of WPM solution (supplied by Lactalis Ingredients), and the third was mulberry leaf extract (supplied by Phynova).
The WPI and WPM test products contained 78.9% and 86.8% of whey protein and 8.4% and 10.7% of caseins, respectively. The MLE contained 12.5mg of the active ingredient 1-deoxynojirimycin (DNJ), consumed either before or during the meal.
In the protein pre-meal study, 15 healthy subjects were recruited and consumed a standardised breakfast composed of 56g of white bread (two slices), 25g of jam and a glass of 330ml of orange juice. Supplements were consumed 30 or ten minutes (at least) pre-meal.
The MLE study involved 30 subjects and a meal comprising 150g of boiled white jasmine rice, 25g of white bread, 80g of curry sauce and 80g of chicken breast slices.
Acute postprandial glycaemic response was monitored with a continuous glucose monitoring device.
WPM was more efficient than whey protein isolates (WPIs) at reducing PPGR, although “the mechanism of action explaining the stronger PPGR reduction induced by the WPM pre-meal is unclear”, the authors say.
Low dose, pre-meal whey protein (10 g) reduced PPGR by decreasing the gastric emptying rate but, when hydrolysed, it lost its ability to reduce PPGR, “suggesting that a faster amino acid absorption could impair the effectiveness of the whey protein pre-meal on the glucose response of the following meal”.
The timing of administration was important in obtaining the optimal effects of MLE on PPGR and positive outcomes were more apparent when consumed with a meal rather than five minutes before.
The authors comment: “These findings not only further advance the technical applications of these nutritional supplements in different food formats, but also the relevance of obtaining optimal health benefits to lower the risk of T2D or its complications.”
They add that their observations are “highly likely” to be relevant for healthy subjects as well as subjects with diabetes.
Published online: https://doi.org/10.3390/nu14132674
‘Effect of Different Nutritional Supplements on Glucose Response of Complete Meals in Two Crossover Studies’
Nele Gheldof et al.