Ingesting the spice led to reductions in blood insulin levels, the hormone responsible for controlling blood sugar levels, and increased levels of a peptide reported to work by delaying the emptying of the stomach (gastric emptying), according to results of a small study involving 15 people.
Despite the increases in glucagon-like peptide-1 (GLP-1), no effects on gastric emptying, feelings of satiety, or changes in blood sugar levels were reported. The results are published in the new issue of the American Journal of Clinical Nutrition.
“Our finding that cinnamon decreases the insulin demand, despite the lack of change in blood glucose concentrations, was probably due to enhanced glucose uptake via stimulation of the insulin receptor,” wrote the researchers, led by Joanna Hlebowicz from Malmo University Hospital.
The study adds to a growing body of research reporting that active compounds in cinnamon may improve parameters associated with diabetes. Indeed, the same researchers reported in the same journal in 2007 that consumption of 300 g rice pudding plus 6 g cinnamon led to a decreased rate of gastric emptying.
Taking into account the earlier studies, Hlebowicz and her co-workers added: “Higher doses of cinnamon are apparently required to influence GER and postprandial blood glucose concentrations.”
The researchers measured the rate of stomach emptying (gastric emptying rate) in 14 healthy subjects with normal fasting blood glucose levels after consuming 300 grams of rice pudding or 300 g rice pudding plus 6 g cinnamon.
The Scandinavian researchers recruited 15 health subjects (nine men) with an average age of 24.6, an average BMI of 22.5 kg/m2, and with no history of diabetes, and assigned them to randomly consume 300 grams of rice pudding with zero, one or three grams of cinnamon (Cinnamomum cassia; Santa Maria AB, Sweden) added. All of the participants consumed all the meals in a random order, with one week between each.
No significant effects on the rate of gastric emptying, levels of satiety, and blood glucose levels were reported. However, the insulin response one and two hours after the meal with three grams of the spice was significantly lower than levels after consuming the control meal.
Furthermore, the change in GLP-1 response was significantly higher after ingestion of the pudding with three grams of cinnamon, compared to the control meal, said the researchers.
“There seems to be a relation between the amount of cinnamon consumed, the delay in gastric emptying, and the reduction in postprandial blood glucose concentrations,” wrote the researchers.
“The previously described reduction in postprandial blood glucose concentrations after the ingestion of six grams of cinnamon was much more noticeable than was the lowering of GER,” they added.
“Gastric emptying, as well as other factors, regulates the postprandial blood glucose response, and a delay in gastric emptying leads to a lower postprandial blood glucose concentration.”
Cinnamon and diabetes
Despite numerous studies championing the role of cinnamon for diabetes management, a recent meta-analysis questioned the potential benefits of cinnamon for type 2 diabetes. The analysis considered only five randomised placebo-controlled trials involving 282 subjects, and found no significant benefits of cinnamon supplement on glycated haemoglobin (A1C), fasting blood glucose (FBG), or other lipid parameters.
The Scandinavian researchers make reference to the potential in diabetes, while also acknowledging the meta-analysis results. “Clearly, a long-term clinical trial involving a larger number of diabetes patients is needed to evaluate the effects of cinnamon supplementation in type 2 diabetes,” wrote Hlebowicz and her co-workers.
Source: American Journal of Clinical Nutrition 2009, Volume 89, Pages 815–821“Effects of 1 and 3 g cinnamon on gastric emptying, satiety, and postprandial blood glucose, insulin, glucose-dependent insulinotropic polypeptide, glucagon-like peptide 1, and ghrelin concentrations in healthy subjects” Authors: J. Hlebowicz, A. Hlebowicz, S. Lindstedt, et al.