The results of the new study, published on-line in the Elsevier journal Diabetes Research and Clinical Practice, add to a growing body of research reporting anti-diabetic effects of the pine bark extract, Pycnogenol.
"Diabetes mellitus type II is a serious disease with rising prevalence," said lead researcher Dr. Petra Hogger. "This study is crucial for those suffering with the disease because it affirms that Pycnogenol is more effective than [a] prescription medication and supports the abundance of other research done on Pycnogenol and diabetes."
An estimated 19 million people are affected by diabetes in the EU 25, equal to four per cent of the total population. This figure is projected to increase to 26 million by 2030.
In the US, there are over 20 million people with diabetes, equal to seven per cent of the population. The total costs are thought to be as much as $132 bn, with $92 bn being direct costs from medication, according to 2002 American Diabetes Association figures.
Hogger and co-researcher Angelika Schafer from Wurzburg University tested Pycnogenol, a green tea extract (Emil Flachsmann) and the synthetic compound acabrose (Glucobay, Bayer Vital) for their ability to inhibit alpha-glucosidase, an enzyme found in the large intestine that is involved in the metabolism of carbohydrates and the production of glucose.
By inhibiting the activity of the enzyme it could be possible to prevent typical high-glucose peaks in the blood stream after a meal.
The in vitro study used an assay of alpha-glucosidase activity with equal concentrations of each sample and report that the most potent inhibition of the alpha-glucosidase was achieved by the pine bark extract (quantity required 50 per cent inhibition five micrograms per millilitre), followed by the green tea extract (20 micrograms per millilitre) and finally the acarbose (one milligram per millilitre).
"Since the alpha-glucosidase enzymes are located in the duodenum the intact pine bark extract constituents could exert inhibitory effects on alpha-glucosidase before a secondary metabolism of the procyanidin oligomers by bacteria occurs of the lower intestinal tract," wrote the researchers.
"Our results contribute to the explanation of clinical anti-diabetic effects of Pycnogenol," they said.
To identify which compounds in Pycnogenol may be behind the inhibiting effects, the researchers tested four different fractions (phenol carbonic acids and monomeric polyphenols; dimeric and trimeric procyanidins; tetrameric up to hexameric procyanidins; and higher oligomeric compounds).
The latter of these fractions inhibited the enzyme's activity by 94 per cent.
"The results obtained assign a novel, local effect to oligomeric procyanidins and contribute to the explanation of glucose-lowering effects of Pycnogenol observed in clinical trials with diabetic patients," wrote the researchers.
The actual mechanism by which these oligomeric procyanidins inhibit alpha-glucosidase is not clear, and more research is needed to elucidate these effects. Additional in vivo studies are needed to support these effects.
Horphag Research, manufacturer of Pycnogenol, has been very active in sponsoring and supporting studies into the potential health benefits of the pine bark extract and was the funding source behind this latest study.
The first research was conducted on the ingredient 35 years ago. Victor Ferrari, research chief operating officer and executive vice president of Horphag Research, told NutraIngredients recently that the company ploughs $1.5m - "most of its profits" - into research each year.
The product is extracted from the bark of the Maritime pine that grows on the southern coast of France, and is currently used in over 400 dietary supplements, multi-vitamins and health products.
Source: Diabetes Research and Clinical Practice Published on-line ahead of print, doi: 10.1016/j.diabres.2006.10.011 "Oligomeric procyanidins of French maritime pine bark extract (Pycnogenol) effectively inhibit alpha-glucosidase" Authors: A. Schafer, P. Hogger