Coffee has been associated with an array of health benefits recently. Last month, Medical News Today reported on a study suggesting that coffee consumption may reduce the risk of type 2 diabetes. Now, new research finds that drinking the beverage may protect against deteriorating eyesight and even blindness.
Researchers from Cornell University in Ithaca, NY, recently published their findings in the Journal of Agricultural and Food Chemistry.
We all know the main ingredient in coffee as caffeine - the stimulant that gives us that boost. But according to the research team, including senior author Chang Y. Lee, green coffee beans (raw coffee) only contain 1% caffeine.
However, each raw coffee bean contains around 7-9% chlorogenic acid (CGA) - an antioxidant that has been associated with many health benefits, such as weight loss and reduction of blood pressure.
Past studies have also indicated that CGA may be a powerful neuroprotectant, and there has been great interest in identifying neuroprotective compounds that block hypoxia - deprivation of oxygen in areas of the body.
Researchers found that coffee extract and CGA protected mice against retinal degeneration.
The retina - a thin layer at the back of the eye that is made of light-sensitive cells and other nerve cells that are responsible for receiving and organizing visual information - is prone to hypoxia.
"The retina is one of the most metabolically active tissues in the body, consuming oxygen more rapidly than any other tissues, including the brain," the researchers explain.
"Therefore, it is susceptible to a variety of diseases caused by oxidative stress, including age-related macular degeneration, diabetic retinopathy, and glaucoma - all of which can lead to partial or complete blindness."
The investigators were interested to see whether coffee, particularly CGA, may prevent hypoxia and overall degeneration of the retina in mice.
CGA and coffee extract reduced retinal cell death
For their study, the team first tested the effects of CGA on retinal ganglion cells (RGCs) - the neurons located near the inner surface of the retina - that were exposed to hypoxia. Cell damage was reduced with nitric oxide treatment alone, but was reduced further if cells were pretreated with CGA.
The team then induced retinal damage in the eyes of mice using a process called optic nerve crush. They tested the effects of coffee extract and CGA on the mice.
They found that both CGA and coffee extract reduced RGC death in the mice by preventing down-regulation of Thy-1 - a cell surface protein.
Commenting on the findings, the researchers say:
"This study shows that CGA and coffee extract are responsible for reduction of the RGC apoptosis induced by hypoxia and nitric oxide. Therefore, coffee consumption may provide additional health benefits by preventing retinal degeneration."
Earlier this year, Medical News today reported on a study suggesting that drinking two or more cups of coffee a day may reduce liver cirrhosis death risk by 66%, while other research finds that a high coffee intake may help against prostate cancer.
But not everyone believes coffee is good for us. A 2013 study published in Mayo Clinic Proceedings associated the consumption of four cups of coffee a day with a risk of early death. Other research suggests that men who drink two cups of coffee a day are more likely to have urinary incontinence.
You can read more about the health benefits and risks associated with coffee consumption in our Knowledge Center article titled, "What are the health benefits of coffee?"
Written by Honor Whiteman