Goji berries a potential arsenal against age-related macular degeneration

Eating a small serving of dried goji berries regularly shows promise in preventing or delaying the development of age-related macular degeneration (AMD) in healthy middle-aged men and women, as reported in a study.

Used in traditional Chinese medicine for more than two millennia, goji berries or wolfberries are the fruit of two species of shrubby bushes, Lycium chinense and Lycium barbarum, found in northwest China. These fruits contain zeaxanthin and lutein—compounds that are central to filtering out harmful blue light and providing oxidative protection in the macula. [Nutrients 2017;9:120]

Indeed, a team of researchers from the University of California, Davis (UCD) in the US found that consuming 28 grams or about a handful of dried goji berries five times a week for 90 days resulted in a significant increase in the density of protective macular pigments. Meanwhile, the intake of a commercial supplement that contained 6 mg of lutein and 4 mg zeaxanthin did not have the same effect. [Nutrients 2021;13:4409]

Skin carotenoids also markedly increased in the goji berry group at day 45 (p=0.025) and day 90 (p=0.006) but not in the commercial supplement group.

The study included 31 healthy participants (mean age 56 years), of whom 16 had been randomized to receive goji berries and 15 the supplements. A daily goji berry serving provided 28.8 mg of zeaxanthin. Sufficient extraction of lutein from the goji berry samples could not be obtained, although previous work estimated a lutein content of 0.15 mg in 28 g of goji berries from six different goji berry samples. [Ind Crops Prod 2013;47:51-57]

The interventions were generally safe and well tolerated, with no documented adverse symptoms other than minor intestinal gas in one participant in the goji berry group. 

Eye sunscreen

“Lutein and zeaxanthin are like sunscreen for your eyes,” lead author Xiang Li, a doctoral candidate in the Nutritional Biology Program of UCD, said in a statement.

“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,” Li added.

The fruit has been touted to have ‘eye brightening’ qualities in Chinese medicine. Unsure which disease ‘eye brightening’ targets, Li examined the bioactive compounds in goji berries and found copious amounts of lutein and zeaxanthin, which are known to reduce the risk of eye diseases related to AMD.

Notably, zeaxanthin in goji berries is available in a highly bioavailable form, according to Li. This means that the compound is readily absorbed in the digestive system so the body can use it.

The current treatment for intermediate stages of AMD uses special dietary supplements that contain vitamins C, E, zinc, copper, and lutein and zeaxanthin. No known therapy has yet been shown to impact the early stages of AMD.

AMD has many causes, which involve a mix of genetic risks, age-associated changes, and environmental factors like smoking, diet and sun exposure, according to study coauthor Dr Glenn Yiu, an associate professor in the Department of Ophthalmology and Vision Sciences in UCD.

Patients with early stages of AMD do not present symptoms, but physicians can detect AMD and other eye problems during a regular comprehensive eye exam, Yiu added.

Yiu echoed Li, saying that their study “shows goji berries, which are a natural food source, can improve macular pigments of healthy participants beyond taking high-dose nutritional supplements.”

“The next step for our research will be to examine goji berries in patients with early-stage AMD,” Yiu said.