Pterostilbene

Pterostilbene is a stilbenoid chemically related to resveratrol. It is thought to be the key compound found predominantly in blueberries (as well as grapes) that exhibit anti-cancer, anti-hypercholesterolemia, anti-hypertriglyceridemia properties, as well as fight off and reverse cognitive decline. It is believed that the compound also has anti-diabetic properties, but so far very little has been studied on this issue. Additionally, it is also touted as a potent anti-fungal.

Cognitive decline
In a study of 40 19-month-old rats fed either a normal diet or a diet containing blueberry, strawberry, or spinach extracts, the rats that were fed blueberry extracts had a significant reversal in motor-skill decline due to aging as well as other cognitive impairments. All of the diets above, except the normal one, resulted in some reversal or reduction of cognitive decline but none greater than the blueberry group. Even when animal based studies yield positive results, the effects on humans may not be the same.

Lowering blood lipids and cholesterol
Studies that used animals fed on blueberry based diets found significant reduction in blood lipid count and cholesterol count. While lipids and cholesterol stored in the cells do not pose much harm, elevated lipid and cholesterol levels in the blood have been linked to heart disease and stroke. In the mentioned study blueberries were found to be more effective than ciprofibrate, a cholesterol-lowering drug predominantly used outside the United States. According to the study pterostilbene binds to PPARs, breaking down the cholesterol.

Diabetes
Similar to what has been discovered with the drug metformin, pterostilbene has been shown to lower blood glucose levels in rats by as much as 42 percent, although at this point very little research has been conducted to conclusively follow this out.

Latest Revelations
Rimando and UIC collaborators made a huge discovery in 2002, when—in tests using rat mammary glands—they found that pterostilbene possessed cancer-fighting properties at similar effective concentrations as resveratrol. Also in that study, Rimando, Oxford plant physiologist Stephen Duke, and scientists at the University of Buenos Aires in Argentina found that pterostilbene is a powerful antioxidant.

Through experiments using mice, rats, and hamsters, Rimando and collaborators have since helped add chapters to what’s known about pterostilbene and what it can do. In her latest studies, Rimando and scientists at the University of Medical Science in Poznan, Poland, led by Renata Mikstacka, showed pterostilbene’s potential as a cancer-inhibiting compound with regard to inhibiting enzymes that activate chemical carcinogens. Using mice cells, they demonstrated that pterostilbene, as well as other analogs of resveratrol, potently inhibits an enzyme called cytochrome P450. Cytochromes are found within the cells of animals, plants, bacteria, and other microorganisms that transport electrons. They’re also a factor in people’s varying response to drugs and toxins entering their bodies. Cytochrome P450 enzymes activate a variety of compounds known as ”procarcinogens,” which can turn substances such as cigarette smoke and pesticides into carcinogens.

Pterostilbene showed strong inhibitory activity—much more than resveratrol—against a particular form of cytochrome P450,” Rimando says. “This may explain the cancer-preventive property it demonstrated in a mouse mammary gland culture assay.” But she warns that more studies are needed to explain this process as well as those of other trans-resveratrol compounds.

Human studies
Though no thorough human studies have been done, it is generally supported by the mentioned articles that these effects would hold true with humans. However, how much one would have to consume to achieve equivalent results remains in question.

In wine
While resveratrol has been touted for its heart healthy benefits, pterostilbene is not found in wine despite darker grapes having the highest concentrations among the fruit. The reason believed is that it is unstable in light and air.