SAN DIEGO — Age-related macular degeneration (AMD) and cataracts are two ocular conditions that have been shown to be prevented by lutein, a carotenoid antioxidant found in dark green, leafy vegetables such as spinach, kale and collard greens.
“There is an overwhelming amount of evidence to show that lutein and zeaxanthin play a protective role in helping to protect the eye against cataracts and macular degeneration,” said Steven G. Pratt, MD, an assistant clinical professor of ophthalmology at the University of California here. “Lutein and zeaxanthin are not the entire picture because they work in concert with many other antioxidants and other carotenoids; however, certainly without those two nutrients the eye is in big trouble. You need those nutrients to help prevent oxidative stress in the back of the eye and to prevent the damage from blue light hitting the macula. Among other things, lutein and zeaxanthin function as a blue-light filter.”
Dr. Pratt was a consultant for the recently released report “Dietary Reference Intakes for vitamin C, vitamin E, selenium and carotenoids,” prepared by the Institute of Medicine. The report summarizes several studies on AMD and cataracts. Some studies using blood carotenoid concentrations suggest protective effects against risk of AMD. “There are probably at least 20 risk factors which play a part in whether you will develop one or both of these diseases,” Dr. Pratt said. “Vitamin C, vitamin E and glutathione also work with the carotenoids lutein and zeaxanthin.” In addition, “the polyphenols and the omega-3 fatty acids probably play a role, as do zinc and manganese.”
---Purified lutein and zeaxanthin in crystalline form.
In men, dietary intake of carotenoids, fat and iron — as well as plasma concentrations of lutein and zeaxanthin — were positively related with macular pigment optical density (MPOD), but only plasma concentrations of lutein and zeaxanthin were associated with MPOD values for women. On the other hand, “the people who have the most lutein and zeaxanthin in the retina have the clearest lens and a less chance of developing a cataract,” Dr. Pratt said. “The same nutrients that protect against AMD also help protect against cataract. Lutein and zeaxanthin are found in the lens of the eye. We don’t understand their full role. They may be functioning as an antioxidant or as a blue-light filter to protect the retinal photoreceptors from blue light.”
In any event, “the take home message is eat green leafy vegetables on a daily basis, avoid cigarettes and cigarette smoke and also take a well-balanced supplement that contains a multiple array of antioxidants and phytonutrients,” Dr. Pratt said.
From a global perspective, “the three major stressors on eyes are sunlight, inadequate nutrition and lifestyle,” said Robert Abel Jr., MD, an ophthalmologist in private group practice in Wilmington, Del. Regarding nutrition, “the soil is partially depleted, and we don’t always eat or digest properly.” Moreover, “the liver provides the nutrition for our eye.” With sunlight, “some of the blue light is toxic. So ultraviolet and blue light can impact negatively on the retinal photoreceptors.”
Lutein in the limelight
Lutein has recently garnered much attention for a number of reasons. “Along with zeaxanthin, lutein has been identified in the macula,” said Dr. Abel, who was also a consultant on the report. “There have also been a number of large studies, including The Beaver Dam Eye Study and The Eye Disease Case-Control Study, that have concluded green leafy vegetables are important for vision and prevention of macular disease, macular degeneration specifically.” Furthermore, “we now have something that is measurable. This particular carotenoid reflects ultraviolet and blue light; therefore, it gives the yellow color.”
Studies indicate that by taking between 2 mg and 10 mg of lutein per day, “you can increase your serum carotenoid level,” Dr. Abel said. “Using heterochromic flicker photometry, one can measure macular pigment density, which is a new term for evaluating the health of the retina.” When taking lutein, “patients say they can see better.” In addition to eating green leafy vegetables, Dr. Abel recommends corn and eggs.
Overall, though, “we have to realize that visual acuity is not simply a Snellen eye chart,” Dr. Abel said. “Contrast sensitivity is far more sensitive. There are patients who will tell you that they don’t see as well, but in a dark room they still measure pretty well on an eye chart. These are the patients who will tell you after taking lutein or adding lutein to their multi-vitamin that they see better.”
Dr. Abel advises all patients to eat as healthy as possible, plus supplementation. “By the time the patient presents, he presents with a problem, unless you pick it up on a routine exam,” he said. “I think the patient is behind the eight ball and needs the additional nutrition.”
Dr. Abel recommends between 2 mg and 6 mg of lutein a day, preferably as part of a multi-vitamin, “so you receive other important ingredients for retinal health.” In a recent study, “2.4 mg of lutein doubled the serum level,” he said. However, over 6 mg “is probably more than you need, even though we have yet to find any toxicity.”
For Your Information:
- Steven G. Pratt, MD, can be reached at 9850 Genesee Ave., Ste. 310, La Jolla, CA 90237; (858) 457-3010; fax: (858) 457-0028. Dr. Pratt has no direct financial interest in any of the products mentioned in this article. He is a paid consultant for Alcon.
- Robert Abel Jr., MD, can be reached at 3501 Silverside Rd., Wilmington, DE 19810; (302) 477-2600; fax (302) 477-2650; e-mail: email@example.com. Dr. Abel has no direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
- The full report, “Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium and Carotenoids,” is available online at www.nationalacademies.org.