The Versatility of GinkgoGinkgo Improves Vision in
Some Cases of Glaucoma
This versatile, ancient herb has many benefits, even for those who are healthy
By Aaron W. Jensen, Ph.D.
e take many things for granted. Every morning when we wake up, we expect to be able to walk, hear, and see as well as we did the day before. But all it takes is an unfortunate accident to limit any of these activities and throw our entire existence into chaos. Think of how difficult it is to perform daily activities after twisting an ankle, straining a muscle, or getting laryngitis. Simple and routine tasks become challenging.
True, these are only temporary inconveniences. So imagine what would happen if you lost one of these functions permanently and were no long able to walk, hear, or see. Sadly, this is slowly happening daily to large segments of the population, without warning. Many chronic and debilitating diseases, such as osteoporosis and glaucoma, have no obvious early warning signs, and by the time such diseases are diagnosed, considerable damage may already have been done.
Glaucoma Takes Varied Forms
Glaucoma is a particularly difficult disease to come to terms with, as it limits the one sense on which we are most dependent: sight. Glaucoma—a family of diseases that ultimately leads to vision loss caused by damage to the optic nerve—takes varied forms, including open-angle, narrow-angle (or angle-closure) and normal-tension glaucoma. All of these conditions are distinct in the way the disease progresses; but they have one commonality—they lead to the gradual and often irreversible loss of vision.
For many years, it was believed that high intraocular pressure (IOP) was the main cause of optic nerve damage in glaucoma. IOP is definitely a high risk factor for this disease, but it is now known that individuals with normal IOP can also develop glaucoma. This form of the disease is called normal-tension glaucoma (NTG); it is most common in people of Japanese descent and those with systemic heart conditions characterized by an arrhythmia, or irregular heartbeat.
An investigation sponsored by the Glaucoma Research Foundation has concluded that approaches used to lower IOP (e.g., medication or surgery) are effective in keeping NTG under control. In addition, research by Italian scientists reveals that herbal therapies may also be beneficial for NTG, as they have demonstrated that Ginkgo biloba improves visual field damage in some patients with NTG.
Ginkgo Improves Blood Circulation
It seems that ginkgo is everywhere these days—so why did researchers use this particular herb to investigate vision in glaucoma patients? There is a good reason. It has long been known that ginkgo improves blood circulation, presumably by reducing the tendency of blood to clot and thus help maintain blood flow to sensitive tissues, such as the brain and optic nerve. Improved blood flow to these organs, the researchers reasoned, may ease the course of glaucoma.
Ginkgo helps maintain blood flow
to sensitive tissues, such as the
optic nerve, which may ease the
course of glaucoma.
To test their theory, the Italian researchers recruited 27 patients between the ages of 58 and 80 (median age 70) for a clinical trial; each patient had NTG in each eye and reported progressive loss of vision over time. The patients were divided into two groups in a crossover design. One group received 40 mg of a typical Ginkgo biloba extract (24% flavone glycosides, 6% terpenes) three times daily for 4 weeks, followed by a washout period (no treatment) of 8 weeks, followed by placebo for an additional 4 weeks. The other group received the same treatment in the reverse order. Standard measurements to determine the extent of visual field loss were recorded in each phase of the trial.
Ginkgo Improves Vision in Glaucoma
As expected, the placebo had no impact on visual performance. When the NTG patients in either group were treated with the ginkgo extract, however, each measurement of visual field showed significant improvement. An additional result of this study was that the visual benefit was lost following cessation of the ginkgo treatment. That is, during the washout period, visual field performance returned to baseline levels, indicating that ginkgo must be continually consumed in order to produce clinical benefits.
In a published commentary on this paper, a prominent eye researcher, Dr. Robert Ritch, Chief of Glaucoma Services at the New York Eye and Ear Infirmary, stated, “The authors are to be commended in embarking along this innovative avenue of research. Ginkgo biloba extract deserves further investigation for its potential in the treatment of glaucoma as well as other ischemic ocular diseases.” Stay tuned for more news on this topic.
Brain, Eyes, or Both?
Researchers note that visual field improvement may result from either improved retinal ganglion cell function or improved cognitive function. At this point, it is unclear whether ginkgo’s neuroprotective benefit is derived from improved blood flow to the brain or to the eyes, or both. Regardless, ginkgo has multiple benefits, and much research supports the ability of this ancient remedy to improve cognitive function in elderly adults.
Managing the Risk Factors for Glaucoma
If you have glaucoma, is there anything you can do on a daily basis to improve your condition? A recent study suggests that regular exercise may be a good ally in fighting glaucoma by reducing eye pressure and decreasing other risk factors, such as diabetes and high blood pressure.
The study found that people with glaucoma who exercised regularly over a period of three months, by riding a stationary bike four times a week for 40 minutes, could reduce their intraocular pressure (IOP) by about 20% on average—and they were in better physical condition at the end of the three months! Ongoing exercise was required, though, to maintain the IOP improvement, because if the subjects neglected their exercise for more than two weeks, the improvement was lost.
Researchers have also noted that vitamin E added to regular glaucoma medication improves visual field in the majority of patients studied. In addition, vitamin E also shows promise in the treatment of premature retinopathy.
Other lifestyle changes that may improve glaucoma include limiting caffeine intake and not drinking large quantities of water all at once (a better approach is to drink small amounts frequently throughout the day). Both caffeine and overly large “slugs” of water can increase IOP transiently and exacerbate the condition.
- Glaucoma Research Foundation funded research. http://www.glaucoma.org/treating/treatment/alt_meds.html
Ginkgo improved performance in
retention, storage, and
retrieval of information.
Cognitive studies with ginkgo have routinely been conducted in cognitively impaired individuals. A recent trial, however, was conducted in cognitively intact individuals—people who reported no history of dementia or significant cognitive impairment—with interesting results. The researchers recruited 262 subjects, average age 60, and randomly divided them into two groups to receive either 180 mg of EGb 761 (a widely used, standardized Ginkgo biloba extract containing 24% flavone glycosides and 6% terpene lactones) or a placebo, for 6 weeks.
Ginkgo Improves Brain Function in Healthy Individuals
The researchers found that ginkgo supplementation improved the subjects’ performance in several neuropsychological tasks compared to the placebo group, including the retention, storage, and retrieval of information, based on a test called the Selective Reminding Test. The ginkgo group also performed better on a test used to measure visual recognition (such as human faces), called the Wechsler Memory Scale. The researchers were appropriately cautious about overinterpreting this result, however, as the differing baseline scores of the two groups complicated the situation.
27% of the ginkgo subjects rated
their own ability to remember as
“somewhat improved” or
But did the ginkgo-gobbling subjects actually feel more mentally empowered at the end? Actually, they did, registering a statistically significant memory improvement as measured by self-analysis: 27% of the ginkgo subjects rated their own ability to remember as “somewhat improved” or “much improved,” compared with only 17% of the placebo group. As a result, this study suggests that ginkgo is good not only for the cognitively impaired but also for those who are cognitively healthy.
The Perfect Combination
Accidents that rob you of your natural physical and mental abilities can happen at any time. Good health is no accident, however. It takes planning and commitment to make choices that allow you to live an active and healthy life. Of course, attention to your diet and exercise is essential, but you can buttress this prudent approach by making other smart choices, such as arming your body with
the nutrients it needs to protect against chronic disease and maintain sharp mental focus.
A strong mental capacity coupled with good health is the best guarantee of a high quality of life. So go out and take a walk, come back and read a good novel, and chances are that you will be able to keep on doing exactly that for a long time indeed.
- Quaranta L, Bettelli S, Uva MG, Semeraro F, Turano R, Gandolfo E. Effect of Ginkgo biloba extract on preexisting visual field damage in normal tension glaucoma. Ophthalmology 2003;110:359-64.
- Ritch R. Discussion of Quaranta et al. article. Ophthalmology 2003:110:362-4.
- Mix JA, Crews WD. A double-blind, placebo-controlled, randomized trial of Ginkgo biloba extract EGb 761 in a sample of cognitively intact older adults: neuropsychological findings. Hum Psychopharmacol Clin Exp 2002;
The Wonders of Ginkgo
For centuries, Ginkgo biloba has been used internally and externally to address a variety of health concerns, and it has figured prominently in traditional Chinese medicine. Traditional healers didn’t know exactly why ginkgo was beneficial—they just knew that it worked!
But now, thanks to advances in biochemistry and molecular biology, we better understand how ginkgo works its wonders. Many of the health benefits are attributed to specific compounds called ginkgolides, flavonoids, and terpenes that are found in ginkgo leaves. These natural compounds interact with many different tissues in the body and are especially beneficial for the cardiovascular and nervous systems. Listed below are some of the specific health benefits of ginkgo:
- Increases cerebral and peripheral blood flow
- Protects against damage from impaired blood flow (ischemia)
- Increases red blood cell flexibility, so the cells flow through capillaries more easily
- Inhibits platelet aggregation and thrombus (blood clot) formation
- Scavenges free radicals to protect against oxidative damage
- Promotes neural function by increasing neurotransmitter uptake and receptor density
- Decreases age-related cerebral changes and helps to preserve mitochondrial function
- Increases brain alpha-wave activity and reduces theta-wave activity to promote relaxation
- Exhibits neuroprotective effects and inhibits death of neural cells
Benefits of Keeping the Brain and Body Active
Let’s face it: every year of our existence increases our risk of chronic disease. But the sharper we keep our mind and body, the lower our risk of suffering from diseases such as glaucoma and Alzheimer’s. And the more we use our faculties, both mental and physical, the longer we may be able to outrun the inevitable.
In fact, a study published in The New England Journal of Medicine shows that elderly people who engage in mental stimulation and leisure activities, such as reading, board games, dancing, and playing musical instruments, have a reduced risk of dementia. Not surprisingly, greater engagement produces greater results: for example, elderly individuals who fought their way through the mental gymnastics of a crossword puzzle four days a week had a 47% lower risk of dementia than those who deigned to pursue this activity only once a week.
But to work a crossword puzzle or read a book, you need to be able to see, right? So having good vision into the later years of your life serves you well in your fight against dementia as well. Everything is connected . . . sharp eyes may foster sharp minds.
- Verghese J, Lipton RB, Katz MJ, et al. Leisure activities and the risk of dementia in the elderly. N Engl J Med 2003;348:2508-16.
Dr. Jensen is a cell biologist who has conducted research in England, Germany, and the United States. He has taught college courses in biology and nutrition and has written extensively on medical and scientific topics.