Mycoprotein and glycemic response
There is evidence to suggest that Mycoprotein may be useful in the management of obesity and type 2 diabetes as it appears to show beneficial effects on glycemia (glucose in the blood) and insulinemia (insulin in the blood).
By decreasing the rate of glucose absorption, the amount of insulin secreted by the pancreas is reduced, lessening the impact of the ‘insulin peak’. Periodic high peaks of insulin secretion are thought to contribute to the development of type 2 diabetes and heart disease, so a reduced glycemic response is desirable.
The mechanisms by which Mycoprotein reduces the rise in postprandial blood glucose are thought to be associated with its high fibre content. Fibre delays the passage of food into the small intestine (Leclère et al. 1994).
As a result, the glucose is absorbed more slowly. Additionally, the presence of soluble, viscous fibre slows the diffusion of glucose across the small intestinal wall bringing about an improved glycemic response (Edwards et al. 1988).
Mycoprotein contains mainly beta-.glucans and chitin, which are partially soluble. However, it has been proposed that the chitin can undergo deacetylation to form a more soluble compound called chitosan, adding to the soluble proportion of fibre in the food (Turnball & Ward 1995).
Mycoprotein has a low carbohydrate content so it is unlikely that the delayed breakdown and absorption of its carbohydrate alone would result in the observed improvements in the glycemic response. Instead, it is the effect that it has on the digestion of carbohydrate present in the foods eaten at the same meal occasion that is bringing about the proposed benefit.
Interest in the anti-glycemic effect of Mycoprotein was sparked by an early observation by researchers Turnball & Ward (1995) who investigated the glycemic response in 19 healthy subjects. The study was a randomised crossover design with each subject receiving either a test meal (20g Mycoprotein) or control meal, in random order, with a 7-day washout period between the 2 meals.
They observed that the serum glucose response was lower throughout the entire 120 minute post-prandial period following the Mycoprotein meal compared to the control. The insulin response was also lower. The only nutritional difference between the test meals was the dietary fibre content (the Mycoprotein meal contained 11.2g more dietary fibre) so the authors suggest that it is the viscous polysaccharides that are reducing postprandial glycemia and insulinemia.