Vision and Botanical Medicine

35 million Americans are at risk of never seeing the sunset again, never seeing their grandchild step up to the plate in the Little League game, and never reading their favorite book one more time. This is a number of Americans who are estimated to have eye diseases including macular degeneration (AMD), diabetic retinopathy (DR), cataracts and glaucoma. These four illnesses, in their different forms, are all capable of causing blindness in their bearers. Together, they form a formidable obstacle to the promise of good health as we age.

And yet, there’s precious little that conventional medicine has to say about the natural treatment of these illnesses, and even less to say about their prevention. The most frequent strategy to deal with cataracts, which will affect over 30 million Americans by 2020, seems to be watching them until they get bad enough to operate on. Macular degeneration, predicted to affect 3 million Americans by 2020, is likewise treated with a “watch and wait” strategy, while glaucoma (2,2 million by 2020) is addressed symptomatically but not holistically. And diabetic retinopathy, the all too common result of years of diabetic damage to the small vessels of the retina that will affect 4.4 million Americans by 2020, is not treated until it’s frequently too late. Fortunately, there is much in natural, botanical medicines that can offer hope for people with these visual illnesses.

The first thing to realize is that all of these illnesses involve some of the same biochemical mechanisms gone awry. The first mechanism involves what we call oxidative stress.  In this model, stresses of all sorts (chemicals, environmental stressors like cigarette smoke and radiation, hormonal stressors including high insulin levels, and even emotional stresses) create what are called reactive oxygen species (ROS).  These supercharged molecules affect the mitochondria of the cell, setting off a chain reaction which results in programmed cell death, called apoptosis.  Reactive oxygen species can also do their damage in the cells by directly stimulating something called the JNK signaling pathway, a direct pathway that also leads to apoptosis of the cell. Finally, oxidative stresses also promote the production of ceramide, a lipid product in the cell. Ceramide can also boost the activity of the JNK signaling pathway, or it can be altered by an enzyme called Caspase–3.  Both of these activities result in, you guessed it, cell death or apoptosis.

In another group of pathways, inflammation triggers the release of TNF alpha, an inflammatory cytokine. This stimulates the macrophage factor NF kappa B which releases inflammatory factors including interleukin 6 (IL-6).  The end results are both cell death and more inflammation, which reinforces the pathways.

Notice that, in the description of these mechanisms of cell death, I haven’t yet mentioned eye diseases specifically.  Although in this case the cell death I am talking about is the cells of the retina, the cornea and the other structures of the eye, I could just as well be talking about the cells of the kidney, the peripheral nerves, the joints, the heart and other organs  that are affected by aging.  In fact, aging is largely a process in which oxidative stress leads to ROS and inflammation and, eventually, to cell death.  Have you ever wondered why the same natural substances (curcumin, resveratrol, quercetin, etc.) keep coming up as helpful for all these illnesses?  This is because these incredible herbal medicines have direct effects on the oxidative stress, inflammation and apoptosis pathways, and therefore affect multiple illnesses that involve these pathways.

One of the most valuable botanical medicines is curcumin. Curcumin is the active component of the common kitchen herb turmeric. One of the basic reasons that curcumin is so helpful is that it’s stable in stomach acid. Therefore, it does not break down moving through the digestive tract. Curcumin can be anti-inflammatory, through its control of some of the enzymes of the inflammation pathway, including cyclooxygenase-2 (COX-2) and lipoxygenase.  It also interferes with the production of TNF alpha, the critical  cytokine in the apoptosis and inflammation pathways.  In rat studies, curcumin has been found to protect against radiation damage and hydrogen peroxide damage to the retina. Other studies have shown that curcumin can prevent against damage of diabetic retinopathy. Still other animal studies have demonstrated the protective effect of curcumin against cataract formation, both diabetic cataracts and nondiabetic cataracts. The authors of one review study concluded that “the anti-oxidative and anti-inflammatory properties of curcumin still make it a compound of choice in the treatment and prevention of AMD, DR, and cataracts.”1

Another kitchen herb that has a remarkable effects the prevention and treatment of eye diseases is the herb saffron. The active ingredients of saffron, crosin and crocetin, protect the cells against ROS, leading to the reversal of planned cell death and oxidation. Saffron blocks the action of Caspase-3, the enzyme that leads to apoptosis. It also interferes with the aforementioned ceramide-JNK pathway to cell death, by and increasing the levels of the critical antioxidant glutathione. Test tube trials have shown that saffron protects retinal cells against oxidative stress. Rat trials have shown the benefit of saffron in protecting the eye against light and radiation exposure. Other animal trials have shown the protective effect of saffron on the formation of cataracts, seemingly by protecting the lens cells against oxidative damage. And human trials have shown benefit of saffron supplements in improving early macular degeneration (AMD).

Resveratrol, a polyphenol found in red wine amongst other things, has been studied for its positive effects on cardiovascular function and diabetes.  However, it also has uses as a protectant in the eye, since it is protective against reactive oxygen species. Resveratrol has been shown to prevent damage to optic nerve cells in patients suffering from glaucoma.2 Animal studies have shown increases in glutathione and decreases in oxidative stress of the lens, suggesting its use in preventing cataract formation. And several studies have demonstrated the effect of resveratrol in preventing diabetic complications, including retinopathy.

The Chinese herb Danshen, also called Salvia or Asian red sage, also contains polyphenols which are anti-inflammatory and antioxidants. In a mouse study looking at diabetic retinopathy, danshen was injected into the retinal tissue and prevented the loss of vision. Intravenous danshen has shown benefit in glaucoma. Due to its inhibition of TNF alpha, danshen has been shown to protect the retinal cells. And preclinical studies suggest that danshen can help prevent AMD as well.

A few months ago I told you about quercetin and its use in preventing and treating prostate cancer. This remarkable flavonoid, found in vegetables, berries and tea, has also been studied for its usefulness in visual disorders. Quercetin is another botanical substance that has antioxidant activity and therefore has been shown to inhibit the formation of oxidative stress induced ROS. Overgrowth of small blood vessels in the retina (called angiogenesis) are important in the formation of AMD, and quercetin has been shown to slow down this angiogenesis. In 2011 quercetin beat other antioxidants in a study of cataract inhibition, while other studies have shown a role for quercetin in the prevention of diabetic complications, including retinopathy.

Any discussion of plant-based antioxidants for the eye must include two carotenoids with hard to pronounce names, lutein and zeaxanthin.  These pigments which are commonly found in many fruits and vegetables, are shown in epidemiology studies to correlate with lower incidences of AMD. It is thought that these pigments absorb blue light entering the retina, which protects the retina against highlight exposures. A recent clinical study demonstrated that supplementing with lutein and zeaxanthin slow down the development of AMD and improved vision.

With these herbs and similar herbs like ginkgo biloba, ginseng and green tea extract, nature has given us many choices for improving vision and preventing the scourges of aging eyes, including macular degeneration, cataracts, diabetic retinopathy and glaucoma.

1.) Tuan-Phat Huynh, Shivani N. Mann, and Nawajes A. Mandal, “Botanical Compounds: Effects on Major Eye Diseases,” Evidence-Based Complementary and Alternative Medicine, vol. 2013

2.) Neuroprotective Effects of Resveratrol on Cerebral Ischemia-Induced Neuron Loss Mediated by Free Radical Scavenging and Cerebral Blood Flow Elevation