Numerous studies on the health benefits of dried goji berries have emerged over the past decade, leading growers to explore the idea of planting the Chinese native, and the latest discovery could prove huge.
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,” says study co-author Glenn Yiu, associate professor in the Department of Ophthalmology and Vision Sciences.
Also known as wolfberry, boxwood, and wedding vine, goji berries can be grown in nearly every U.S. state and Canadian province, according to Penn State University Extension. The Goji plant is a slightly thorny deciduous woody shrub, typically 3 to 6 feet tall when cultivated and pruned, although plants can reach 12 feet tall in their natural state. Goji is part of the nightshade family (tomato or nightshade), so its cultural and nutritional needs are similar.
In the UC Davis study, 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.
HOW IT WORKS
The pigments that increased in the group, 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,” says lead author Xiang Li, a doctoral candidate in the nutritional biology program. “The higher the lutein and zeaxanthin in your retina, the more protected you are. Our study found that even in normal, healthy eyes, these optical pigments can be increased with a small daily serving of goji berries,” says Li.
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 as popular as herbal teas. 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”.
“There are many types of eye disease, so it’s not clear which disease ‘eye brightening’ targets,” Li says.
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 with 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.
DYK? Dried Goji Berries May Prevent Age-Related Vision Loss