Second Sight This section is compiled by Frank M. Painter, D.C.
Send all comments or additions to: Frankp@chiro.org
From The April 1999 Issue of Nutrition Science News
By Patrick Quillin, Ph.D., R.D., C.N.S.Colorful fruits and vegetables provide necessary nutrients to see late into life
Our eyes are called the windows to the soul. Besides offering a focal point to direct one's attention when talking with another person, eyes bring in more than 90 percent of the information entering the average human brain, according to some psychologists.
Scripture referred to "an eye for an eye." Mohandas Gandhi countered with "An eye for an eye makes the whole world blind." Since Israel is a sunny land, it is not surprising that several of the people Jesus healed were blind; perhaps they suffered from cataracts or macular degeneration. From books to computers and television to sunsets and art galleries, it is clear that vision plays a major role in the life of the functioning adult.
"The part can never be well unless the whole is well." --Socrates
Vision loss is a catastrophic issue facing the aging population. But proper nutrition can help prevent -- and possibly reverse -- the most common visual disorders, namely cataracts and macular degeneration.
Vision for cataract sufferers is somewhat like trying to see through eyeglasses smeared with salad oil. For macular degeneration sufferers, vision is like having a penny taped to the center of your glasses: poor central vision but better peripheral vision.
Cataract Attack
Cataracts are white cloudy spots on the normally transparent lens of the eye. Lens clouding may cause blurred vision, sensitivity to light and glare, fading or yellowing of colors, poor night vision and halos around lights. Cataracts are the leading cause of decreased vision in Americans older than 65 and the leading cause of blindness in the world. [1] At least 40,000 Americans are blinded by cataracts, and 4 million Americans suffer from some degree of cataract-induced visual impairment. Now that the average life expectancy of Americans is in the 70s, the incidence of cataracts is expected to double in the next 12 years. Cataract surgery is the most common surgical procedure for elderly Americans, costing Medicare about $3.5 billion per year.
Cataract formation is associated with several biochemical changes in the eye's lens: decreased levels of the key antioxidants glutathione and vitamin C; increased lipid, amino acid and protein oxidation; increased sodium and chemically uncombined free calcium, another free radical producer; loss of amino acids; and decreased lens metabolism. [2]
One research study found the most protective foods against cataracts are broccoli, corn, kale, spinach and tomato sauce.
Long-term high intake (greater than 1,000 mg/day) of vitamin C has been linked with a substantially reduced risk of cataracts. [3]The U.S. Recommended Dietary Allowance for vitamin C is 60 mg, but that measurement is only the minimal amount needed to stave off deficiency conditions. It does not address the amount of nutrients needed for therapeutic purposes. The association between high levels of vitamin C and better vision may be linked to the unique structure of the lens, which is avascular (lacking blood vessels) and suspended in extracellular fluids, like a clear water balloon floating in a tub of water. To get enough vitamin C into the lens of the eye, one must have more than survival amounts of vitamin C in the blood. Increased dietary intake of vitamin C leads to increased concentration of ascorbate in the aqueous medium of the eye, which protects the lens from damage. [4]
Ultraviolet radiation-B from sunlight has been implicated in cataracts, but the damage is greater when a vitamin C deficiency is present, indicating that ascorbate and possibly other antioxidants protect against sunlight damage. [5] Too much rusting (oxidation) and not enough protection (antioxidants) can lead to cataracts. Other helpful antioxidants include vitamin E, selenium, glutathione and the thousands of bioflavonoids and carotenoids found in a diet of fresh, colorful vegetables and fruits. These colorful pigments contain antioxidants critical to protecting and restoring vision. One study found men who ate the greatest amounts of the carotenoids lutein and zeaxanthin were 18 percent less likely to develop cataracts. The most protective foods were broccoli, corn, kale, spinach and tomato sauce. [6]
Supplementing with the bioflavonoid bilberry (Vaccinium myrtillus) and vitamin E halted cataract formation in 49 of 50 patients in one study. [7] Beta-carotene also acts as a special filter to protect the lens of the eye from excessive oxidation. [8]
Maintaining adequate selenium levels is also important in preventing cataracts. For example, patients with a type of cataract called nuclear cataracts, whose risk factors include poor nutrition and smoking, have lower levels of vitamin E and selenium in the lens. Low selenium also accounted for a 2,500-percent increase of free radical-inducing hydrogen peroxide (H2O2) in the lens. The H2O2 is neutralized by the selenium-dependent antioxidant enzyme glutathione peroxidase. [9] The lens-protective glutathione peroxidase is also dependent on the amino acids methionine, cysteine, glycine and glutamic acid. [10]
Zinc and vitamin A as beta-carotene, nutrients often in short supply in the American diet, are integral to the functioning of the eye. Zinc affects retinal metabolism and may treat macular degeneration. [11]
A high-risk lifestyle that may contribute to cataract formation includes frequent exposure to glaring sunlight, such as sunny climates or reflections from snow or cars, coupled with insufficient antioxidant intake.
Dairy products contain lactose, the unique disaccharide composed of the monosaccharides galactose and glucose. An inability to properly metabolize galactose may be the culprit in 30 percent of cataracts in a study of 22 cataract patients under age 50. [12] Thus, avoiding dairy products may help those with a family history of cataracts.
Clearly, lifestyle, overall health and sunlight exposure in the presence of deficient antioxidant protection play a crucial role in the development of lens opacities. Cataracts can be prevented, delayed, slowed and possibly even reversed if caught in the early stages by aggressively addressing the underlying causes of the disease. Researchers from Oxford University Clinical Cataract Unit in England offer cautious optimism regarding antioxidant protection: "Middle-aged and elderly patients may benefit from a supplement. An intake in excess of the recommended daily intake may be beneficial, but this is not proven." [11]
Macular Degeneration
The macula is the area of the retina where images are focused--the portion of the eye responsible for fine vision. Degeneration of the macula, called age-related macular degeneration (AMD), is the leading cause of blindness in people older than 65 in the United States and Europe. [13] An estimated 150,000 Americans are legally blind from macular degeneration and 20,000 new cases occur annually. There are two types of AMD: atrophic, or "dry" type, which represents 95 percent of AMD cases; and neovascular, or "wet" type, which occurs when abnormal blood vessels leak blood and fluid that damage the macula. The wet type is best treated with laser photocoagulation therapy.
In the more common dry AMD, the retinal pigmented epithelium (RPE), the innermost layer of the retina, gradually accumulates cellular debris called lipofuscin that leads to a gradual loss of vision from the center outward. Hence, one of the more common symptoms of early-stage AMD is good peripheral vision but poor central vision.
Risk factors for AMD include smoking, cardiovascular disease (atherosclerosis, arteriosclerosis, hypertension) and low dietary intake of pigmented antioxidants found in green, orange and red vegetables and fruits.
The principal components of the macula are the carotenoid plant pigments lutein and zeaxanthin. [14] Autopsied AMD eyes showed 30 percent less lutein and zeaxanthin than non-AMD eyes. The macular pigment is believed to protect against AMD, specifically by guarding against reduced visual sensitivity, a precursor to AMD. One study provided 30-mg lutein supplements (from Aztec marigolds) for 140 days to subjects. The goal was to determine the effects of lutein on the macular pigment optical density; low density is thought to represent a risk factor for AMD by permitting greater damage by light at the blue end of the spectrum. Blue light damages photoreceptors and the RPE. The result was a 39 percent increase in macular pigment optical density and a 30 to 40 percent reduction in blue light reaching the RPE. [15]
In another study, 38 people took a nutritional supplement containing beta-carotene, vitamins C and E, copper, manganese, riboflavin, selenium and zinc. The supplement improved vision in 40 percent of 38 regular users, compared to 16 percent who improved in the intermittent-use control group. [16] After six months, vision and contrast sensitivity improved in 88 percent of those who supplemented regularly. Another study found that supplementing diets with spinach and corn, good sources of lutein and zeaxanthin, bolstered the macular pigment in most, but not all, of the 13 subjects tested. Notably, the increases in macular pigment density were obtained within four weeks--and remained elevated for several months after resuming an unmodified diet. [17]
Jonathan Wright, M.D., an integrative physician in the Seattle area, used an intravenous solution of nutrients containing 400 mcg selenium and 10 mg zinc infused twice weekly, plus daily oral supplements of 300 mcg selenium, 60 mg zinc picolinate or citrate, 800 IU vitamin E and 2 g taurine between meals to reverse AMD in two patients. [18]Although this case study offers far from irrefutable data, it offers hope in contrast to allopathic medicine's bleak track record for treating AMD. Additional research must be conducted to see if these results can be repeated.
Visualize a Better Lifestyle
Oxidative stress, or the predominance of free radicals over protective antioxidant mechanisms, has been implicated in most causes of death and disability in the United States, including premature aging, heart disease, cancer, rheumatoid arthritis, Alzheimer's disease as well as visual problems. [19]
Humans "rust," not unlike a cast-iron nail left outside in the elements. Antioxidant supplements have demonstrated a role in slowing the rusting--the preventing, delaying or reversing--of most conditions of aging including cardiovascular disease, non-insulin-dependent diabetes mellitus, hyperglycemia, elevated plasma lipids, and general oxidative stress. [20] A lifestyle that enhances circulation and general health will likely lower the risk for common visual disorders and may be instrumental in reversing these conditions. Rusting may be slowed with protective nutrients, which act like varnish painted over the nail.
The average adult body consists of 60 trillion cells being fed through 60,000 miles of blood vessels. Our lifestyle--diet, exercise, attitude, toxin avoidance--dictates whether these blood vessels are vibrant and supple or constricted and hardened and thus unable to properly nourish the eyes. The average heart pumps 55 million gallons of blood throughout a lifetime. Lifestyle dictates whether this blood has the consistency of water or yogurt, which decides how well the tiny capillaries in the eye region are being nourished. By age 65, the average American has eaten the equivalent of not one elephant, but 25 elephants, or about 50,000 pounds of food. [17]The cumulative effect of that diet comes home to roost in later years.
The typical American diet is high in fat and sugar, with serious deficiencies in vitamins, minerals, antioxidants and essential fatty acids. The net result is poor general health. It would be naive to think that an unhealthy 65-year-old overweight, chain-smoking person who has spent decades in a self-destructive lifestyle can continue this lifestyle and just take a few bilberry pills to reverse advanced cataracts. We need to respect all the body's needs, not just some for good vision. Thus, exercise, stress management, blood-sugar control and toxin avoidance contribute to whether nutrition will help regain one's vision.
"The part can never be well unless the whole is well," wrote Socrates. You cannot have healthy eyes without a healthy body.
Patrick Quillin, Ph.D., R.D., C.N.S., is director of nutrition at the Cancer Treatment Centers of America Inc., in Tulsa, Okla. (www.4nutrition.com). He has written 14 books that have sold more than 1 million copies.
Sidebars:
How We See
Vegetable Power
References:
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2. Varma SD, et al. Prevention of cataracts by nutritional and metabolic antioxidants. Crit Rev Food Sci and Nutr 1995;35:111-29.
3. Jacques PF, et al. Long-term vitamin C supplement use and prevalence of early age-related lens opacities. Am J Clin Nutr 1997;66:911.
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13. U.S. Department of Health and Human Services. The 1983 report of the national advisory eye council: visual research--a national plan:1983-7. Bethesda (MD), NIH Publication No. 83-2469.
14. Bone RA, et al. Preliminary identification of the human macular pigment. Vision Res 1985;25:1531-5.
15. Landrum JT, et al. A one year study of the macular pigment: the effect of 140 days of a lutein supplement. Exp Eye Res 1997;65:57-62.
16. Seddon JM, et al. A prospective study of cigarette smoking and age-related macular degeneration in women. JAMA 1996; 1141-6.
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19. Mezzetti A, et al. Systemic oxidative stress and its relationship with age and illness. J Am Geriatric Soc 1996;44(7):823-7.
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21. Sampson HA. Food hypersensitivity: manifestations, diagnosis, and natural history. Food Tech 1992 May:141-4.
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