Broccoli can deliver therapeutic benefits, study says

July 21, 2016
Compound found in broccoli may be used to develop a possible treatment for age-related macular degeneration.

Today is National Junk Food Day—a perfect entrée for doctors of optometry to talk to their patients about nutrition and "food as medicine" when it comes to their eye health. And a new study showing the benefits of broccoli when it comes to age-related eye conditions reinforces that sentiment.

Food as medicine is a phrase attributed to Hippocrates, the Greek physician known as the father of Western medicine. It may not be a new concept, but it remains relevant.

Take, for instance, a new study titled, "A novel AhR ligand, 2AI, protects the retina from environmental stress" by the Buck Institute for Research on Aging in Novato, California. Published in the online journal Scientific Reports in June, researchers there increased 10-fold the strength of a compound found in broccoli to develop a possible treatment for age-related macular degeneration (AMD).

They were inspired by a compound found in broccoli called indole-3-carbonol (I3C), which can also be found in other leafy vegetables such as Brussels sprouts, cabbage, collards, cauliflower and kale. In the eyes, IC3 helps to remove environmental toxins by setting in motion aryl hydrocarbon receptor proteins (AhR). AhR can trigger the detoxification of the retina.

The challenge was that researchers needed a better activator for AhR than I3C. After a search, they found a better trigger: 2,2′-aminophenyl indole (2AI), which is 10 times more potent than I3C.

"2AI protected human retinal cells in culture from stress," the study's lead author Arvind Ramanathan, Ph.D., says. "And it also protected retinal cells in mice from light-mediated damage. We are very excited about the potential for 2AI and look forward to developing it further."

He adds, "You would have to eat an unreasonable amount of broccoli and other cruciferous vegetables to get enough of a protective effect to impact AMD. This method allows us to capitalize on nature's wisdom to find related molecules that can deliver therapeutic benefit."

AMD, which causes damage to the macula near the center of the retina, is the leading cause of vision loss and blindness for people 65 years and older in this country.

Study significance

"Using a compound in broccoli that has been shown to clear environmental toxins from cells, I3C, the researchers were able to synthetically engineer a more potent compound to boost its actions on the AHR receptor, thereby reducing cell death in the retinas of the mice studied," says Julie Poteet, O.D., a certified nutrition specialist and vice president of the Ocular Nutrition Society, who practices in Acworth, Georgia.

Steven Newman, O.D., who practices in Miami, Florida, is a certified nutrition specialist. Dr. Newman also serves on the advisory board of the Ocular Nutrition Society.

"The study is significant in that it shows that the aryl hydrocarbon receptor protein (AhR) plays a critical role in the RPE (retinal pigmented epithelial layer of the retina) cell homeostasis as a stress response pathway and by modulating lipid metabolism," Dr. Newman says.

"RPE homeostasis is critical in age-related macular degeneration retinas," he says.

He notes a concern: AhR appears to inflame breast cells, so he urges doctors of optometry to wait for further studies before changing their treatment recommendation.

Juicy conversation

Yet, doctors of optometry can't go wrong by encouraging their patients to eat a nutritious diet including more fruits and vegetables. He cited the example of lutein and zeaxanthin, potent eye nutrients that protect the eyes from harmful ultraviolet rays. And studies suggest they are associated with better vision. Diets rich in these two antioxidants appear to protect against age-related eye diseases such as AMD and cataracts.

"The greatest aspect of this study is that it brings the subject of 'food as medicine' to the front of the minds of optometrists," Dr. Newman says. 

"I ask my patients what they had for breakfast. You can find out a lot of information from their answer. The more we can get our patients to talk to us, the better information we have to treat them. It can provide a roadmap of their health."

Says Dr. Poteet: "Studies that single out compounds from plants, though important, fail to take into consideration the synergistic effects of all the beneficial compounds in plant-based foods. These effects are often not only additive but multiplicative in their benefits. Emphasizing diets rich in produce to our patients is not only suggested, but an absolute necessity in providing them with the tools to maintain eye health and integrity."

The AOA follows all research closely, including potential treatments for AMD; however, more research is needed regarding treatment for AMD. For more information or help for better vision, please visit the AOA website.

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