Eyeworld

EW NEWS & OPINION 20 February 2015 by Maxine Lipner EyeWorld Senior Contributing Writer Potential new ophthalmic perk for coffee drinkers a protective effect against these free radicals," Dr. Lee said. After conducting this research in the laboratory, the investigators subsequently treated the mice di- rectly, in some cases using ocular in- jections of the chlorogenic acid and in others using feeding experiments. The idea was to consider whether chlorogenic acid, when consumed, could reach the retinal tissue after passing through the digestive tract. "When you drink coffee, prob- ably less than 20% is absorbed as chlorogenic acid. The rest of the acid eventually decomposes," he said. "Our interest is how these so-called Coffee appears to offer protective effect against retinal degeneration C offee consumption may prove helpful for more than a quick pick-me-up. One of the compounds contained in coffee beans may help prevent retinal degenera- tion, study results published in the January 2014 issue of the Journal of Agricultural and Food Chemistry suggest, according to Chang Y. Lee, PhD, professor of food chemistry, Cornell University, Ithaca, N.Y. Dr. Lee has been working with phytochemicals in antioxidant and anti-cancer activity for the last 20 years. "Our main concentration has to do with fruits and vegetables and herbs and includes teas, coffee, and other herbal products," he said. One area of interest has been the phenolic compounds, he noted. "These phenolic compounds are common in most fruits and vege- tables, as well as in beverages and herbal tea," he said, adding that one of these compounds in partic- ular, chlorogenic acid, has been of interest to the laboratory due to its antimicrobial, anti-inflammatory, and DNA protective effects. "Chlorogenic happens to be one of the major compounds in coffee—actually more than caffeine content," Dr. Lee said. "Our interest was in chlorogenic acid in terms of eye health." Holim Jang, a graduate student in Dr. Lee's lab, and Sang Hoon Jung, PhD, Korea Institute of Science and Technology, Seoul, took the lead in studying this. Eyeing oxidative stress Dr. Lee explained that the retina is one of the most metabolically active tissues in the body, with a high con- sumption of oxygen. These natural metabolic activities produce reactive oxygen species (ROS) as byproducts. "When our bodies have enough antioxidants, we balance out oxida- tion and maintain our good health," he said. If this balance is broken down, oxidative stress is created, which allows damaging free radicals to dominate. These free radicals damage other tissues including DNA and protein. With this in mind, investigators created oxidative stress in the eyes of mice and considered what effect, if any, chlorogenic acid might have. When normal tissue from the mice was exposed to nitric oxide under hypoxic conditions, investigators found that when untreated there was severe damage due to free radicals, Dr. Lee said. "However, if we treated that tissue with chlorogenic acid or coffee extract and exposed it to the free radicals under the hypoxic conditions, the chlorogenic acid had metabolites are absorbed, distribute through our body system, and go to the eye tissue. Recently we found that some chlorogenic acid metab- olites, such as dihydrocaffeic acid, caffeic acid, and dihydroferulic acid, have also shown beneficial effects," Dr. Lee said. In particular, there is an optical barrier of tissue that these compounds must pass through, he explained. In recent research, investigators have found that some metabolites pass through that barrier and reach the retina and provide the health benefit effect. Increasing strain With more stressors on the retina than ever, Dr. Lee thinks that the beneficial effects of coffee may be more important than ever as well. "Our retina diseases over the last several years have been increas- ing due to high usage of computers by young as well as old people and the tiny characters on phones," he said. "It is my understanding that eye disease and the rate of retinal degeneration has been increasing." In addition, because the pop- ulation as a whole has been aging, retinal degeneration, which is common among senior citizens, has also increased, Dr. Lee said. Drinking coffee could poten- tially stave off eyestrain, retinal degeneration, diabetic eye disease, and some types of glaucoma, Dr. Lee noted. With study results in mind, he thinks it might be prudent to urge patients to drink more coffee. The next step, he said, requires human clinical trials. But because of their early findings, he recom- mends opting for coffee as a drink of choice. If chlorogenic acid and its metabolites are found in human trials to protect the eye from degen- eration, they have the potential to provide the pharmaceutical industry with new active compounds to use in the development of new agents, he concluded. EW Editors' note: Dr. Lee has no financial interests related to his comments. Contact information Lee: cyl1@cornell.edu " If we treated [normal] tissue with chlorogenic acid or coffee extract and exposed it to the free radicals under the hypoxic conditions, the chlorogenic acid had a protective effect against these free radicals. " – Chang Y. Lee, PhD

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