By KATHLEEN BITTER
Good news for caffeine addicts: a Cornell-led study indicates that drinking coffee may prevent degradation of the retina caused by eye stress and ageing.
According to Prof. Chang Lee, food science, a co-author of the study, areas of the body with high rates of metabolic activity produce a high number of reactive oxygen species, or ROS. When there is a buildup of ROS they can damage the DNA and proteins in a cell and lead to cell death. If these cells are neurons, ROS buildup can lead to neurodegeneration.
The body produces some antioxidants on its own in order to prevent ROS from causing damage, but with age or extra stress on a certain area the antioxidants available may not be enough to keep up with ROS, according to Lee.
Damage caused by ROS and a shortage of antioxidants has been shown to lead to neurodegenerative disorders such as Alzheimer’s and Parkinson’s Disease, Lee said.
Eyesight requires a large amount of metabolic activity, according to Lee, so the researchers were interested in looking at how the antioxidants known to be present in coffee can affect the degeneration of the retina due to stress and age.
“When we take a look at statistics of the last few years, more and more people are having problems with retinal degeneration,” Lee said. “Two reasons: One is the aging population, and the second is that most of us spend lots of time in front of a computer or iPhone.”
The specific antioxidant compound that Lee and Holim Jang grad studied is chlorogenic acid, or CGA. CGA has been shown to have antioxidant properties in previous studies, according to Lee, and when they performed in vitro studies of the effects of CGA on brain tissue they found that it prevented neurodegeneration.
The next step was to look at the effects of CGA in vivo, on living mice. Lee and Jang found that mice that had CGA injected directly into their eyes as well as mice that had been fed a coffee extract had less retinal degeneration than mice that were not treated.
They also showed that in the mice that were receiving the CGA orally through a coffee extract, the CGA was being absorbed through the intestine and making its way up to the retina where it was working as an antioxidant, Lee said.
According to Lee, however, only 10 to 20 percent of CGA is absorbed directly by the digestive tract and circulated through the body. The other 80 percent is broken down by bacteria in the gut into smaller molecules that are then absorbed.
“We also checked whether these compounds have the same activity,” Lee said.
The researchers found that not only do the smaller molecules have the same antioxidant effect on the retina, they also can get into the retina by way of the circulation system in order to act.
“[The compounds] can reach the retina. That is a critical part,” Lee said.
Courtesy of Prof. Chang Lee, food scienceBeneficial beverage | According to Prof. Chang Lee, food science, about 20 percent of chlorogenic acid in coffee is absorbed through the small intestine and the other 80 percent is broken down by gut bacterie into metabolites that are then absorbed. Lee found that both chlorogenic acid and its component metabolites were beneficial for long-term eye health.