"...I'm blind as a bat," responded Marilyn Monroe, when asked if she was "myopic" in the 1953 movie How to Marry a Millionaire. Cast as a severely near-sighted gold digger who walks into walls because "Men aren't attentive to girls who wear glasses," the 1953 film unearths humor in a common vision problem.
However, for many Americans, sight is not a laughing matter. Few disabilities are as much feared as failing vision. Some 3.4% of Americans aged 40 and over have some type of visual impairment. And, as with most age-related health conditions, rates are expected to double over the next 30 years, the result of Baby Boomers growing older.
Glaucoma, diabetic retinopathy, and macular degeneration are the leading causes of irreversible blindness, notes a recent article in FDA Consumer.
Approximately 1.7 million Americans have a form of age-related macular degeneration (AMD), according to the National Eye Institute (NEI). AMD is characterized by a "breakdown" of the eye's macula, causing blurred vision. Progression leads to vision loss. The incidence varies by age, sex and race. Interestingly, in the 50-plus age bracket, white women aged 50 to 59 have one of the lowest rates at 0.18%; however, those aged 85 and over, have the highest rate (13.62%).
Cataracts affect more than half of those over age 65. The condition is marked by opaque areas of the eye lens where proteins "clump together" and distort light, clouding vision. The most common type of cataract is age-related, says the FDA Consumer.
Consumers do act on anxieties related to vision care. Some 33.7% of the general population say they are maintaining or treating "vision problems," up from 28.2% in 1999 for a compounded annual growth rate of 9.32%, according to the Natural Marketing Institute (NMI), Harleysville, Penn.
The 2000 Gallup Study of Eye Health reported that 43% of adults 40 and over were likely to take eye health supplements in the next year, noted Liz Sloan of Sloan Trends & Solutions, Escondito, Calif., at Nutracon 2002. The Study also reports that of this group, 29% were concerned about future cataracts. While diet indirectly relates to diabetic retinopathy, the strongest evidence lies with dietary impact on the ability to reduce risk of AMD and, possibly, cataracts.
Ingredients and Theory
Reduced incidence of AMD is associated with diets high in dark green, leafy vegetables such as spinach and collard or mustard greens. These foods are a rich source of nutrients such as vitamins A, C, and E. Additionally, research indicates this type of produce contains relatively high levels of zeaxanthin and lutein, two chemically similar carotenoids. These are the predominant carotenoids in the eye's macula, with good evidence supporting their benefit in AMD. As antioxidants, they protect photoreceptor membranes and the retina, and as dark yellow pigments, they screen out damaging blue light. (See "On the Web" sidebar.)
Sound support for the benefits of supplementation recently occurred when a clinical trialâ€”called the Age-Related Eye Disease Study (AREDS)â€”sponsored by the National Eye Institute (NEI), one of the federal government's National Institutes of Health, was published in the October 2001 issue of Archives of Ophthalmology.
Some 3,600 people at high risk of developing advanced stages of AMD lowered their risk by about 25% when treated with a combination of the antioxidants vitamin C (500mg), vitamin E (400IU), beta-carotene (15mg), as well as zinc (80mg) and copper (2mg). (The copper was added for decreased absorption of this mineral, due to the high intake of zinc.) For study participants with no or early AMD, however, the nutrients did not appear to provide a benefit.
Support also is growing for the benefits of lutein and zeaxanthin supplementation. "Indeed, a recent review by Tufts [University] researchers of 30 years' worth of scientific evidence has linked 'generous intakes' of lutein and zeaxanthan from foods like spinach and broccoli with as much as a 40 percent reduction in macular degeneration risk," notes a Tufts University Health & Nutrition Letter. The same review also pointed to a 20% reduction in cataract risk.
|Although lutein has been most commonly introduced in pill forms in the U.S., as this article hits the press, lutein-fortified prune juice from Sunsweet Growers, Pleasanton, Calif., and Abbott Laboratories', Abbott Park, Ill., lutein-fortified Ensure beverages, are hitting retail shelves.|
Bilberry to Glutathione
The specific supplement combination in the ARED study did not appear to benefit those with cataracts. However, other studies and logic support supplementation.
Cataracts are due, in part, to oxidation. Antioxidants may be useful, particularly vitamin C, which is found at levels 20 times higher in the eye lens than in the blood. A study by researchers at Harvard-affiliated Brigham and Women's Hospital, Boston, showed daily doses of vitamin C, E and beta-carotene resulted in a "small deceleration" in cataract progression. A recent Nutrition and Vision Project between Tufts University and Harvard University investigators indicated that women with the highest intakes of vitamin C (avg. 360mg/day) had 70% lower odds of developing certain types of cataracts, when compared to those who consumed an average of 140mg/day or less.5 Higher vitamin C consumption and reduced rates of cataracts also was observed in the Second National Health and Nutrition Examination Survey (NHANES II).
Bilberry benefits for both macular degeneration and cataracts are based on its flavonoid (anthocyanoside) content. Besides being a powerful antioxidant with the ability to support vascular health, the flavonoids support a healthy level of rhodopsin (retinal purple), a light-sensitive pigment found in the rods of the retina. Studies have shown bilberry extract to be a potentially effective aid in supporting healthy eye tissue. Commercial extracts on the market commonly are standardized to 25% anthocyanidins, with recommended dosages of 240 to 500mg of extract in tablet or capsule form. The compound is listed in Herbal Medicineâ€”Expanded Commission E Monographs.
Certain omega-3 fatty acids again check in as being potentially beneficial. A multi-center study published in Archives of Ophthalmology concluded: "Higher intake of specific types of fat, including vegetable, monounsaturated, and polyunsaturated fats and linoleic acid, rather than total fat intake may be associated with a greater risk for advanced AMD. Diets high in omega-3 fatty acids and fish were inversely associated with risk for AMD when intake of linoleic acid was low." One theory is that omega-3 benefits might be similar to those in heart health, where blood fat and likelihood of blood clots are reduced.5
In the MarketConsumers are beginning to get the message. According to NMI's Health and Wellness Database, 50% of the general population says it "has heard of" lutein (compared with 53% that say the same for "fortification" and 33% for "isoflavones"). A May 2001 Market Facts Telenation Study for a lutein supplier, by Market Facts, Arlington Heights, Ill., reports that 44% of Americans are aware of lutein, up from 5% in January, 1999.
When R&D, marketing and general managers at food and nutritional companies were asked whether lutein would increase in importance to their product lines, 13% of those surveyed responded in the affirmative in Prepared Foods' own "2002 R&D Investment Survey."
Currently, lutein is a hot ingredient. Bausch & Lomb, Rochester, N.Y., just introduced Ocuvite ExtraÂ®, a supplement building on Bausch & Lomb Ocuvite PreserVision, but with 2mg of lutein, "a beneficial carotenoid found mostly in leafy green vegetables to help maintain ocular health."
Whether bilberry is important to consumers was a choice left up to the consumer by Bluebonnet Nutrition, Sugarland, Tex., which, last year, introduced Eye Antioxidant, formulated with bilberry and lutein, as well as another supplement with only lutein.
Lutein, now armed with self-affirmed GRAS status, increasingly will find its way into foods (see sidebar). Blueberries, lutein, glutathione and other supplementation would not have helped the myopic Marilyn Monroe character, but they may form a crucial weapon in the armament of an aging population.
On the Web: EYE HEALTH
- www.lutein.org â€” Lutein Information Bureau
- www.infantvision.com â€” DSM Food Specialties site on omega fatty acids
- www.drkoop.com/InteractiveMedicine/ConsHerbs/Bilberrych.html â€” Bilberry information, including supporting research
- www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=PubMed â€” Listing of research related to glutathione retina
- www.fda.gov/fdac/features/2002/202_eyes.html â€” FDA Consumer article
- www.fda.gov/fdac/features/2002/202_eyes.html â€” NIH's National Eye Institute
- www.nih.gov/news/pr/oct2001/nei-12.htm â€” Antioxidant vitamins and zinc Reduce Risk of Vision Loss from Age-Related Macular Degeneration study by NEI
- www.preventblindness.org/vpus/vp_contents.html â€” 2002 edition of Vision Problems in the U.S. Report
- www.natmedpro.com/nmp/Refs-Cataract.htm â€” List of published research on compounds benefiting cataracts
References:1 www.nei.nih.gov/eyedata/pdf/vpus_usmap.pdf - National Eye Institute
2 Meadows, M. 2002. Saving Your Sightâ€”Early Detection Is Critical, FDA Consumer Magazine, U.S. Food and Drug Administration. March-April.
4 AREDS Report #8. 2001. Arch Ophthalmol.; 119:1417-1436
5 Tufts University Health & Nutrition Letter. 2002. Jan., p. 4, 5.
6 Simon, J.A. and E. S. Hudes, 1999. Serum Ascorbic Acid and Other Correlates of Self-Reported Cataract Among Older Americans, J. Clin. Epidemiol. 52(12) pp. 1207-1211.
7 Giblin, F.J., 2000. Glutathione: a vital lens antioxidant. J. Ocul. Pharmacol. Ther.; 16(2): 121-35.
8 Seddon, M.J, et al., 2001. Dietary Fat and Risk for Advanced Age-Related Macular Degeneration. Arch Ophthalmol.;119:1191-1199
9 Blumenthal, M., et al. 2000. Herbal Medicineâ€”Expanded Commission E Monographs. Newton, MA: Integrative Medicine Communications.