Raw coffee is, on average, just 1% caffeine, and it contains 7% to 9% chlorogenic acid, a strong antioxidant that prevents retinal degeneration in mice, according to the study, published in the Journal of Agricultural and Food Chemistry.
The retina is a thin tissue layer on the back wall of the eye with millions of light-sensitive cells and other nerve cells that receive and organize visual information. It is one of the most metabolically active tissues, demanding high levels of oxygen and making it prone to oxidative stress. The lack of oxygen and production of free radicals lead to tissue damage and loss of sight. Retinal degeneration can be caused by glaucoma, aging and diabetes.
The study is "important in understanding functional foods, that is, natural foods that provide beneficial health effects," Chang Lee, professor of food science and the study's senior author, said in a statement. "Coffee is the most popular drink in the world, and we are understanding what benefit we can get from that."
Previous studies have shown that coffee cuts the risk of such chronic diseases as Parkinson's, prostate cancer, diabetes, Alzheimer's and age-related cognitive declines.