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Green Tea and Macular Degeneration
Macular degeneration is the most common chronic eye condition I see. Macular degeneration typically affects those over 60 but can be seen earlier in younger patients, especially if there is a family history. Macular degeneration is the leading cause of irreversible visual loss and blindness in the U.S.
The mechanism of macular degeneration is complex. What we know is that degeneration occurs at the center of our vision at the level of the retinal pigment epithelial cells (RPE). These cells are responsible for processing vision, keep the retina healthy by transporting oxidating/damaging elements out of the retina. One of these damaging elements is lipofuscin. If lipofuscin is not recycled out of our photoreceptors, these cells (that help us see) do not work as well. It is thought that if lipofuscin induces oxidative stress in RPE cells when exposed to light, this can reactive oxygen species (ROS).
We currently do not have treatments for dry macular degeneration, the most common form of macular degeneration. That is why it is important to look at what we have available to us, naturally and in our diet, to see if there is anything that could help reduce the oxidative damage in our retina.
Green tea extract has been shown to have antioxidant and anti-inflammatory properties in many disease conditions like obesity, cancer, cardiovascular disease, and neurologic conditions. A study, published in 2016, looked at green tea catechins (GTE)- potent anti-oxidants in green tea extracts- to see if oral administration could treatment or reverse strong oxidative damage to RPE cells in rats. In this study, rats were injection with sodium iodate which is a known toxin that induces selective damage to RPE cells causing retinal degeneration, mimicking age-related macular degeneration. The study found that 14 days after administration of this toxin, rats given GTE, had significantly improved appearance of their RPE cells. It also showed that these extracts improved retinal thickness on optic coherence tomography analysis, which is the same type of imaging test we use to evaluate for macular degeneration in humans. Lastly, GTE suppressed expression of oxidative stress related genes.
This study is a landmark study showing that GTE- specifically Theophenon E, catechins with epigallocatechin gallate, or epigallocatechin gallate alone- can improve the genetic expression, cell function, and retinal appearance in RPE cells after oxidative stress.
Take home: This is good news! Consider adding a cup of green tea to your daily or weekly routines for improved retinal health, specifically macular degeneration protection.
Next week we’ll take a deep dive into which type of green tea may offer you the most health benefit! Was this helpful? Comment below and subscribe for our future newsletter.
Source: Yang et al. Green tea catechins are potent anti-oxidants that ameliorate sodium iodate-inudced retinal degeneration in rats. Scientific Reports, 6:29546, 2016.