Suspensions of freeze dried and powdered P. ostreatus (American oyster mushroom) and P. cystidiosus (abalone mushroom) may influence the activity of an enzyme called glucokinase, an important sensor of glucose levels in the body, report scientists from the University of Sri Jayewardenepura and the University of Colombo, Sri Lanka.
“When consumed for 2 weeks, both fasting and postprandial serum glucose levels were decreased significantly in healthy volunteers, which suggest that long-term consumption of P. ostreatus and P. cystidiosus may be beneficial to humans,” they wrote in Phytotherapy Research.
“Furthermore, P. ostreatus and P. cystidiosus did not cause any hepato-renal damage in the healthy volunteers.”
The Sri Lankan researchers recruited 88 healthy volunteers and randomly assigned them to one of four groups: two control groups, and two mushroom groups receiving either P. ostreatus or P. cystidiosus preparations at a dose of 50 mg/kg/body weight for two weeks. The researchers also assigned 14 type 2 diabetics to receive single 50 mg/kg/body weight doses of the mushroom preparations.
Results for the healthy volunteers indicated that P. ostreatus significantly reduced fasting and postprandial glucose levels by 6.1% and 16.4%, respectively, while P. cystidiosus significantly reduced fasting and postprandial glucose levels by 6.4% and 12.1%
The mushrooms preparations were also associated with improvements in fasting and postprandial glucose levels in the diabetics, while insulin levels increased.
Both mushrooms were associated with increases in glucokinase (GK) secretion, they added, and decreases in glycogen synthase kinase (GSK), which promotes the formation of glycogen in the liver from glucose (and thereby lowering glucose levels).
“P. ostreatus and P. cystidiosus exerted significant hypoglycaemic effect in healthy volunteers challenged with glucose and in Type 2 diabetic patients on diet control,” wrote the researchers. “The mushrooms are neither hepatotoxic nor nephrotoxic. Hence, this study confirms the suitability of P. ostreatus and P. cystidiosus as a functional food for diabetic patients.
“The freeze dried suspensions of the two mushrooms exert their oral hypoglycaemic activity via several possible mechanisms viz increasing GK activity and promoting insulin secretion and thereby increasing the utilization of glucose by peripheral tissues, inhibiting GSK and thereby promoting glycogen synthesis,” they concluded.
Blood sugar management
According to the World Health Organisation (WHO), diabetes affects over 220 million people globally and the consequences of high blood sugar kill 3.4 million every year. If such statistics weren’t scary enough, the WHO is predicting deaths to double between 2005 and 2030.
The total costs associated with the condition in the US alone are thought to be as much as $174 billion, with $116 billion being direct costs from medication, according to 2005-2007 American Diabetes Association figures.
Supplement products, however, cannot make any claims that are related to the disease condition, and claims in the area of blood sugar management have to be carefully crafted.
Jason Sapsin, an attorney in the firm Fox Rothschild, told us recently: “You can talk about maintaining normal blood sugar levels. The key thing to make quite clear in your marketing is that you are starting from a basis of health.”
Source: Phytotherapy Research
Volume 29, Issue 2, pages 303-309, doi: 10.1002/ptr.5255
“Hypoglycaemic Activity of Culinary Pleurotus ostreatus and P. cystidiosus Mushrooms in Healthy Volunteers and Type 2 Diabetic Patients on Diet Control and the Possible Mechanisms of Action”
Authors: W.J.A. Banukie N. Jayasuriya, C.A. Wanigatunge, et al.