The in vitro tests, conducted using mouse and rat liver cells, found that the stimulatory effect only occurred when high doses of cashew seed extract (CSE) were used. Other parts of the cashew plant – including leaves, barks and apples – were also tested, but were not found to have an effect on glucose uptake.
“Of all the extracts tested, only CSE showed significant stimulatory effect on glucose uptake. Extracts of other plant parts had no such effect, indicating that CSE likely contains active compounds, which can have potential antidiabetic properties,” wrote the researchers from the University of Montreal, Canada, and the Université de Yaoundé, Cameroun.
Cashew tree products have traditionally been thought to have anti-inflammatory properties, to help counter high blood sugar and to prevent insulin resistance among diabetics. The new study, published in the journal Molecular Nutrition & Food Research, set out to examine the impact of these extracts on cells that respond to insulin.
Researchers prepared solutions of cashew seed extract to concentrations of 25, 50 and 100μg/mL. They also prepared a solution of 50μM anacardic acid (AA), which is the active component in cashew seed extract.
These solutions were administered to mouse and rat cells, and incubated for 18 hours, with or without insulin, after which the researchers measured glucose uptake.
Both cashew seed extract and anacardic acid were found to stimulate glucose uptake. In the case of CSE, the effect was only noted at the higher concentration of 100μg/mL.
“Glucose uptake was significantly elevated in cells incubated with high concentration of CSE (100 mg/mL) plus insulin as compared with either CSE or insulin alone and similar results were obtained with AA plus insulin. No such synergistic effect was noticed at lower concentration of CSE,” wrote the researchers.
They noted that their findings were preliminary, and that further studies were necessary to determine the exact mechanism of action and whether CSE could have a potential anti-diabetic impact on other insulin-responsive tissues or on pancreatic beta cells.
However, they concluded that the current study “validates the traditional use of cashew tree products in diabetes,” and that their results “suggest that CSE may be a potential anti-diabetic nutraceutical.”
Source: Hydro-ethanolic extract of cashew tree (Anacardium occidentale) nut and its principal compound, anacardic acid, stimulate glucose uptake in C2C12 muscle cells
Mol. Nutr. Food Res. 2010, 54, 1–10
Authors: Leonard Tedong, Padma Madiraju, Louis C. Martineau, Diane Vallerand, John T. Arnason, Dzeufiet D. P. Desire, Louis Lavoie, Pierre Kamtchouing and Pierre S. Haddad