Dried goji berries, a fruit long used in traditional Chinese medicine, may help healthy middle-aged people fight off the causes of eye degeneration, according to a new study out of the University of California, Davis.
The study, published in the peer-reviewed journal Nutrients in December 2021, found that various nutrients in goji berries can help slow age-related macular degeneration (AMD), the leading cause of vision loss estimated to affect 170 million people globally.
Lead study author Li Xiang, a doctoral candidate in the Nutritional Biology programme at the University of California, Davis, said she wanted to pursue the study because she had grown up in northern China and had heard of the “eye brightening” qualities of goji berries.
Years later, Li appears to have given some scientific backing to the oral tradition.
The study compared the results when healthy people ate 28g of dried goji berries for 90 days versus when people took synthetic products that tried to replicate the superfood.
The scientists chose 28g because that is considered one serving size. Then they could analyse how one serving per day impacted participants.
The researchers found that consuming the actual berries makes a big difference. Study participants who ate synthetic forms of the nutrients saw no improvement in a protective pigmentation that is important for eye health.
According to Li, the key chemicals for the study were lutein and zeaxanthin, which “are like sunscreen for your eyes”.
“The higher the lutein and zeaxanthin in your retina, the more protection you have. Our study found that even in normal healthy eyes, these optical pigments can be increased with a small daily serving of goji berries.”
The study found that goji berries significantly impacted the pigments, which protect against blue light and oxidants, suggesting that the berries could help improve even healthy eyes.
The authors theorised that other nutrients in goji berries, such as taurine, vitamin C and zinc, could help strengthen the protective pigments.
A study out of China found similar results, but the authors said that the study had too many intruding factors — such as testing smokers and non-smokers — to be overly trustworthy.
While the California study finds that goji berries can help prevent AMD, the study was not designed to figure out if it could reverse the process if it had already started.
“The next step for our research will be to examine goji berries in patients with early-stage AMD,” said Glenn Yiu, a co-author of the study and an associate professor at the university.
While the synthetic nutrient capsules proved ineffective, the study’s goal was to compare products readily available to shoppers, so the scientists did not break down the nutrients. The authors also noted that the sample size was small, so more studies are needed to confirm the data.
The goji berry has been experiencing a global renaissance over the past few years as its health benefits have become more widely known.
While it has long been a part of diets across China, the northwest autonomous region Ningxia is said to have the highest quality versions of the fruit, according to the BBC.
Goji berries first appear in Chinese history in a book titled The Divine Farmer’s Herb-Root Classic written by a mythological ruler named Shennong, who legend says brought agriculture to ancient China.
The story of Shennong was that he tested all sorts of herbs to find their health benefits, putting the information in the encyclopaedia, which is considered the oldest book about traditional Chinese medicine.
While goji berries were first described in that book, no medical uses were attributed to them until the third century.
Subhuti Dharmananda, from the Institute for Traditional Medicine in the US state of Oregon, said the fruit was not widely used until the end of the Ming dynasty (1368-1644).