Gou Qi Zi (枸杞子), also known as Goji berry, Wolfberry, or Latin name of Lycium Barbarum，is an orange-colored berry that is well-known in Chinese culture as being beneficial for improving vision, and is regarded as an anti-aging food. Gou Qi Zi has been used in traditional Chinese medicine for more than 2000 years, and its use was first recorded around 200 BC in the document called Shen Nong Ben Cao Jing (神农本草经) (1). It is commonly used in soups, tea, drinks, hot pots, and supplements in China.
Why is Gou Qi Zi good for the eyes? Sometimes the mechanisms of why Chinese medicinal foods and herbs are beneficial can be hard to explain with the exception of observations and knowledge from thousands years of practice. Recent intensive research on two vision-related antioxidants lutein and zeaxanthin helped our understanding about Gou Qi Zi’s function.
In mid-1980, Bone and Landrum et al. identified two carotenoids, lutein and zeaxanthin, that were selectively accumulated in the macula region of the retina in human eyes (2, 3). This discovery stirred big interest in the vision research field since age-related macular degeneration is the major cause of severe irreversible vision loss in the western world among people older than 50 years old (4). The macula region of the retina is the region for central vision, which is necessary for tasks such as reading, driving, and recognizing faces. Since the disease leads to blindness, any ways to reduce the onset and progression of this disabling condition had received great attention by the research community as well as people who were being affected.
Lutein and zeaxanthin, both yellow pigments and powerful antioxidants, are believed to filter harmful high-energy blue wavelengths of light and protect the retina from light-induced oxidative damage. Without sufficient protection from these pigments, the retina cells at macular region can be damaged by light-oxidative damage and eventually die, which lead to irreversible loss of vision, as this happens in age-related macular degeneration.
Over the next decades, researchers had collectively demonstrated that increasing carotenoids lutein and zeaxanthin intake either in the diet or by dietary supplements could result in increased blood level, higher macular pigment level in the eye, improve visual function, and delays progression of vison loss. The supplementation of lutein and zeaxanthin not only could delay the loss of vision in people who had already been diagnosed to have age-related macular degeneration, but they could also improve vision sharpness in healthy people from many age groups (5).
In addition, due to the fact that both eyes and brain belong to the central nervous system, scientists studied the effect of lutein and zeaxanthin supplementation on cognitive function. These tests showed that lutein and zeaxanthin could improve brain function by increasing the speed and intelligence in adults and children (6, 7).
The presence of lutein and zeaxanthin in human eye macula region seems to be very selective. There are more than 600 carotenoids found in nature, which are the colorful plant pigments that only plants can synthesize and animals, including humans, cannot produce. Carotenoids include many commonly known plant pigments, such as orange pigment beta-carotene (i.e. carrots and pumpkins), red pigment lycopene (i.e. tomatoes and watermelon), and yellow pigment lutein and zeaxanthin (i.e. leafy greens spinach and kale).
In nature, the lutein to zeaxanthin ratio in plants is about 5 to1. Once these plants are eaten in typical diets, there are more than 20 carotenoids present in human plasma, and some other carotenoids are at the equivalent plasma levels to that of lutein and zeaxanthin, but only lutein and zeaxanthin are found in high quantities in human eyes (2,3,8,9).
Zeaxanthin seems to be more selectively concentrated in the brain compared to lutein. The mean lutein to zeaxanthin ratio was 1.39 to 1 in the brain (10), significantly less than the ratio of 3 to 1 that found in human plasma (2, 11). This finding resembles closely with those found in human retina. Lutein and zeaxanthin are highly concentrated in human retina with the lutein to zeaxanthin ratio of approximately 1 to 2 in the center of the macula to over 2 to1 in the periphery of the retina. Zeaxanthin is selectively concentrated in the center of macula which is the region for central vision (3).
It appears that there are still unknown mechanisms that not only facilitate the accumulation of the lutein and zeaxanthin specifically in the macula, but also reverse the ratio of lutein to zeaxanthin found in plasma, making zeaxanthin dominate in the center of macula and lutein dominate in the peripheral retina. The unique highly selected zeaxanthin at the center of macula and in the brain may suggest its essential role for vision and cognition.
Scientists looked for the best food sources for lutein and zeaxanthin. Good sources of lutein are leafy greens such as spinach and kale, and eggs (yellow color of the egg yolk is from lutein). Gou Qi Zi is the richest natural source known of zeaxanthin, and the uptake and increase of plasma zeaxanthin concentration upon supplementation has been demonstrated (12).In fact, Gou Qi Zi, this orange color raisin-size little berry that has been known for thousands of years in Chinese medicine for improve visual acuity, contains the highest content of zeaxanthin. This definitely can help explain Gou Qi Zi’s benefit for vision known for thousands of years.
In addition to its effect on improving eyesight, Gou Qi Zi had also been reported to have many other health benefits (1) including boosting immune function; preventing and alleviating diabetes; protecting the cardiovascular system from oxidative stress; enhancing sexual function; preventing neurodegenerative disease in the elderly, supporting early brain development in the neonate, and improving brain functions in all ages.
Gou Qi Zi sounds a gift from nature to protect our precious vision and help to improve our health. People are spending most of their waking hours using their central vision staring at screens and reading on mobile devices these days. Electronic devices are emitting blue-light which is also most light-damaging to the eyes. Over time, people can feel eye strain and fatigue. Coupled with the low dietary intake of fruits and vegetables that are high in lutein and zeaxanthin, vision loss from age-related macular degeneration has become a leading cause for vision loss and blindness.
Gou Qi Zi in small quantities over time can offer great protection for your eyes and your health in general. Let’s enjoy this gift from nature.
References
1. Bucheli P, Gao QT, Redgwell R, Vidal K, Wang JK, and Zhang WG. Chapter 14 Biomolecular and Clinical Aspects of Chinese Wolfberry. In Herbal Medicine: Biomolecular and Clinical Aspects. 2nd edition. Editors: Iris F. F. Benzie and Sissi Wachtel-Galor.Boca Raton (FL): CRC Press/Taylor & Francis; 2011.
2. Bone RA, Landrum JT and Tarsis SL. 1985. Preliminary identification of the human macular pigment. Vision Res 25:1531–1535.
3. Bone RA, Landrum JT, Fernandez L and Tarsis SL. 1988. Analysis of the macular pigment by HPLC: retinal distribution and age study. Invest Ophthalmol Vis Sci 29:843-849.
4. Fact sheet from National Eye Institute. https://nei.nih.gov/health/maculardegen/armd_facts
5. Johnson EJ. Role of lutein and zeaxanthin in visual and cognitive function throughout the lifespan. Nutr Rev. 2014 Sep;72(9):605-12.
6. Mewborn CM, Lindbergh CA, Robinson TL, Gogniat MA, Terry DP, Jean KR, Hammond BR, Renzi-Hammond LM, Miller LS. Lutein and Zeaxanthin Are Positively Associated with Visual-Spatial Functioning in Older Adults: An fMRI Study. Nutrients. 2018 Apr 7;10(4).
7. Walk AM, Khan NA, Barnett SM, Raine LB, Kramer AF, Cohen NJ, Moulton CJ, Renzi-Hammond LM, Hammond BR, Hillman CH. From neuro-pigments to neural efficiency: The relationship between retinal carotenoids and behavioral and neuroelectric indices of cognitive control in childhood. Int J Psychophysiol. 2017 Aug;118:1-8.
8. Krinsky NI, Russett MD, Handelman GJ and Snodderly DM. 1990. Structural and geometrical isomers of carotenoids in human plasma. J. Nutr 120:1654- 1661.
9. Khachik F, Spangler CJ, Smith JC, Jr., Canfield LM, Steck A, Pfander H. Identification, quantification, and relative concentrations of carotenoids and their metabolites in human milk and serum. Anal Chem 1997;69:1873-81.
10. Craft NE, Haitema TB, Garnett KM, Fitch KA, Dorey CK. Carotenoid, tocopherol, and retinol concentrations in elderly human brain. J Nutr Health Aging 2004;8:156-62.
11. Handelman GJ, Dratz EA, Reay CC, van Kuijk JG. Carotenoids in the human macula and whole retina. Invest Ophthalmol Vis Sci 1988;29:850-5.
12. Cheng CY, Chung WY, Szeto YT, Benzie IFF. Fasting plasma zeaxanthin response to Fructus barbarum L. (wolfberry; Kei Tze) in a food-based human supplementation trial. Brit J Nutr. 2005;93:123–30.
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