Scientists in Hong Kong, China published the first study ever showing that antioxidant catechins in green tea extract travel from the digestive system to the tissues of the eyes in laboratory animals. Once there, they offer protection against oxidative stress in various parts of the eye.1
The scientists analyzed eye tissue from rats that drank green tea and found that the lens, retina and other tissues absorbed significant amounts of green tea catechins.
Catechins are polyphenols, or phytochemicals, that are found in green and black tea. Studies have found that catechins produce numerous health benefits ranging from supporting healthy glucose levels and cardiovascular health to reducing risk of certain cancers.1
The four main catechins found in tea leaves are epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate ECG), and epicatechin (EC). In this study, the catechins were distributed in different amounts in the eye tissues, with the retina absorbing the highest levels of gallocatechin, and the aqueous humor absorbing epigallocatechin.1
According to the researchers, oxidative stress causes biological disturbances such as DNA damage and activation of proteolytic enzymes that can lead to tissue cell damage and eye diseases.2
“Photo-oxidative stress can inactivate catalase in the lens to initiate cataract formation, while long-term effects of reactive oxygen intermediates could damage retinal tissue cells, retinal pigment epithelium, and choriocapillaries. Oxidation is also associated with primary open angle glaucoma (POAG),” they said.2
What is Glaucoma?
Glaucoma is a major public health problem in this country. The disease causes progressive optic nerve damage that, if left untreated, leads to vision loss. An estimated 3 million people in the United States have the disease, and of these, as many as 120,000 are blind as a result. Glaucoma is the number one cause of vision loss in African Americans. Unfortunately, at least half of the people who have glaucoma are not receiving treatment because they are unaware of their condition.
Lutein in combination with vitamin A slows down vision loss
Another recent study published in the Archives of Ophthalmology found that taking 12 mg of lutein on a daily basis along with vitamin A slows down vision loss associated with retinitis pigmentosa.3
Rentinitis pigmentosa is a group of inherited eye diseases that affect the retina. It causes the degeneration of photoreceptor cells in the retina, bringing progressive vision loss to about one in 4,000 people worldwide.
Lutein is an antioxidant in the carotenoid family—a group of naturally occurring, fat-soluble pigments found in plants—that play a key role in the health of our eyes. Carotenoids are the red, orange and yellow plant pigments that give fruits and vegetables their vivid colors. All fruits and vegetables contain varying concentrations of carotenoids. But their colors are often covered up by green chlorophyll contained in the plant.
Lutein is found in spinach, kale, collard greens, romaine lettuce, leeks, peas, egg yolks, tomatoes, carrots, marigold flowers, and fruits. It accumulates in the macula, the prominent, bright yellow spot in the center of the retina that allows you to clearly distinguish fine detail.
In the study, 225 nonsmoking patients, aged 18 to 60 were evaluated over a four-year period. All the patients received 12 mg of lutein or placebo daily, and all were given 15,000 IU vitamin A palmitate (synthetic vitamin A) with the hope that their mid-peripheral vision would be preserved.3
The results indicate that 40 year olds with the condition who take the vitamin A plus lutein combination would not be expected to lose their mid-peripheral field until the age of 61. This which would represent a significant improvement because the average age of losing mid-peripheral field vision for people not taking lutein plus vitamin A is 51.4
The researchers concluded that lutein supplementation of 12 mg per day slowed loss of mid-peripheral visual field on average among nonsmoking adults with retinitis pigmentosa taking vitamin A. But further studies are needed to assess long-term results.3
- Chu KO, Chan KP, Wang CC, Chu CY, Li WY, Choy KW, Rogers MS, Pang CP.“Green Tea Catechins and Their Oxidative Protection in the Rat Eye.” Journal of Agricultural and Food Chemistry, 2010 Feb 10;58(3):1523-34.
- Byrne, Jane, “Study finds green tea could reduce glaucoma risk.” NutraIngredents.com.
- Berson EL, Rosner B, Sandberg MA, Weigel-DiFranco C, Brockhurst RJ, Hayes KC, Johnson EJ, Anderson EJ, Johnson CA, Gaudio AR, Willett WC, Schaefer EJ. Clinical trial of lutein in patients with retinitis pigmentosa receiving vitamin A. Arch Ophthalmol. 2010 Apr;128(4):403-11.
- Daniells, Stephen. “Lutein plus vitamin A may slow vision loss: Study.” NutraIngredents.com