As an increasing number of studies link consumption of antioxidant-rich foods, including apples, to better health, the next logical step for science is to conduct research into the mechanism behind the beneficial effects. A group of University of California–Davis researchers have discovered one way that apples, with their high flavonoid content, inhibit cellular activity that leads to the development of chronic diseases, including heart disease and age-related cancers. The secret? Compounds in an apple extract can protect cells from damage and death by interfering with communication between cells, according to a team that included Eric Gershwin, professor of allergy, rheumatology and immunology at the UC Davis School of Medicine.
"We've known for a long time that it's the flavonoids in fruits that are protecting the body. We just haven't known exactly how. Now, at least in the case of apples, we have a good idea about what's going on," says. Gershwin.
The findings appear in the May issue of Experimental Biology and Medicine (231:594-598), "Effect of Apple Extracts on NF-B Activation in Human Umbilical Vein Endothelial Cells," by Paul A. Davis, John A. Polagruto, Giuseppe Valacchi, Anh Phung, Karel Soucek,, Carl L. Keen, and M. Eric Gershwin. Previous studies by the group found that chronic consumption of apple juice by human subjects reduced ex vivo low-density lipoprotein (LDL) oxidation, which led to the new research.
The current study, which treated human endothelial cells to an apple-mash extract made from different apple varieties, exposed the cells to tumor necrosis factor, a compound that usually triggers cell death and promotes inflammation via a pathway that involves chemical signaling between cells. "Our study showed that the flavonoids in apples and apple juice can inhibit signals in this pathway that would otherwise damage or kill cells in the body," Gershwin says.
This differs from the effect reported for other flavonoid-rich foods, such as grape seed extracts. The researchers also believe studies indicate that more than just the apple flavonoids provide protection to the cells. "The differences are likely due to the other biologically active ingredients found in the different fruits," Gershwin says. "We need to know more about how fruits like apples are able to protect us from disease."
The study's abstract can be found at http://www.ebmonline.org/cgi/content/abstract/231/5/594.