According to a small randomized trial conducted at the University of California, Davis, eating a small serving of dried goji berries regularly may help prevent or delay the development of age-related macular degeneration, or AMD, in people healthy middle-aged.
AMD is the leading cause of vision loss in older adults and is estimated to affect more than 11 million people in the United States and 170 million worldwide.
“AMD affects your central field of vision and can affect your ability to read or recognize faces,” said study co-author Glenn Yiu, associate professor in the Department of Ophthalmology and Vision Sciences.
Researchers found that 13 healthy participants between the ages of 45 and 65 who consumed 28 grams (about an ounce or a handful) of goji berries five times a week for 90 days increased the density of protective pigments in their eyes. In contrast, 14 study participants who consumed a commercial eye health supplement during the same period did not show an increase.
The pigments that were increased in the group that ate goji berries, lutein and zeaxanthin, filter out harmful blue light and provide antioxidant protection. Both help protect the eyes during aging.
“Lutein and zeaxanthin are like sunscreen for your eyes,” said lead author Xiang Li, a doctoral candidate in the nutritional biology program.
“The higher the lutein and zeaxanthin in your retina, the more protection you get. Our study found that even in healthy, normal eyes, these optical pigments can be increased with a small daily serving of goji berries” , Li said.
The study was published in the journal Nutrients.
Berries used for eye health in China
Goji berries are the fruit of chinese lycium and Lycium Barbarian, two species of shrubby bushes found in northwest China. Dried berries are a common ingredient in Chinese soups and are popular as an herbal tea. They are similar to raisins and eaten as a snack.
In Chinese medicine, goji berries are said to have “eye-brightening” qualities. Li grew up in northern China and became curious if there were any physiological properties to “eye brightening”.
“Many types of eye disease exist, so it’s not clear which disease ‘eye brightening’ targets,” Li said.
She researched the bioactive compounds in goji berries and discovered that they contain high amounts of lutein and zeaxanthin, which are known to reduce the risk of AMD-related eye diseases. The form of zeaxanthin in goji berries is also a highly bioavailable form, according to Li, meaning it’s easily absorbed by the digestive system so the body can use it.
Current treatment for intermediate stages of AMD uses special dietary supplements, called AREDS, which contain vitamins C, E, zinc, copper, lutein and zeaxanthin. No known treatment has yet demonstrated an impact on the early stages of AMD.
The cause of AMD is complex and multifactorial, according to Yiu, and involves a mix of genetic risks, age-related changes and environmental factors like smoking, diet and sun exposure. The early stages of AMD have no symptoms; however, doctors can detect AMD and other eye problems during a regular comprehensive eye exam.
“Our study shows that goji berries, which are a natural food source, can improve macular pigment in healthy participants beyond taking high-dose nutritional supplements,” Yiu said. “The next step in our research will be to examine goji berries in patients with early-stage AMD.”
Although the results are promising, the researchers note that the study size was small and further research is needed.
Other study authors include Roberta R. Holt, Carl L. Keen, Lawrence S. Morse, and Robert M. Hackman of the University of California, Davis.