FRANKFURT, November 25, 2010 /PRNewswire/ -- Who wouldn't want sharp and clear vision for a lifetime? Those who do should take several specific micronutrients. A current scientific review article has confirmed that an optimal supply of the carotenoids lutein and zeaxanthin, as well as the omega-3 fatty acids DHA and EPA, is essential for keeping our eyes healthy. The authors emphasise the potential of these nutrients for protection of the retinal cells and the prevention and treatment of age-related degenerative eye diseases, such as macular degeneration (AMD) in the elderly. Additionally, the European Food Safety Authority (EFSA) recently asserted that taking a dose of 250 milligrams of the omega-3 fatty acid DHA each day, can make an important contribution towards maintaining vision. It is generally difficult to ensure an adequate supply of the aforementioned micronutrients in one's diet, particularly at an older age. For seniors, a risk group, experts recommend an appropriate dosage of food supplements of a similar composition.
Lutein and zeaxanthin play an especially important role in eye function: Both carotenoids form the pigment of the macula ("yellow spot") in the centre of the retina. The macula is responsible for sharp vision. Just like "internal sunglasses," both micronutrients filter out damaging blue light from the sun and UV light. This leads to improved contrast sensitivity and reduced susceptibility to glare, according to scientists. Moreover, both substances keep the retina healthy due to their anti-oxidative, or cytoprotective, and anti-inflammatory effects.
Lutein and zeaxanthin against macula degeneration
The macula pigment breaks down throughout one's life, however, and the function degenerates due to various influences, such as UV light or prolonged computer work. This process - age conditional macula degeneration (AMD) - is insidious and painless. Normally, reading becomes difficult at some point because grey shadows appear in the middle of the text and distort the letters. AMD can lead to blindness and, at 50%, is the most common cause for severe visual impairment in Germany. About 20% of 65-74 year olds suffer from an early form of AMD. A basic differentiation is made between the most common yet treatable "dry" form of AMD and the less common, aggressive "wet" form, which is incurable and can develop from the "dry" form.
All studies have confirmed that preventing AMD depends on a sufficient storage of lutein and zeaxanthin as pigment in the macula. For "dry" AMD, balancing deficits of these carotenoids through diet and supplements improves the vision of those affected. It is therefore important to maintain an adequate supply of lutein and zeaxanthin, researchers say.
Omega-3 fatty acids protect the retina
The omega-3 fatty acids alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docasehexaenoic acid (DHA) are long-chain, polyunsaturated fatty acids. EPA and DHA are important building blocks for cell membranes and are essential for cell growth and regeneration. They also make many contributions to eye health. DHA plays an especially important role in the retina. It keeps the cell membranes flexible (fluidity), which is a vital cell function. It also supports rhodopsin formation and activity, which is a component of "visual purple" in the rod cells (photoreceptors)of the eye's retina and is important for light and dark perception. At the same time, DHA can protect the photoreceptors from "biological cell death" (apoptosis) by oxidative stress. Another protective mechanism of the omega-3 fatty acids could be based on anti-inflammatory characters, such as the formation of anti-inflammatory active substances.
Adequate supply of micronutrients, even using supplementation
The macula pigment density (MPD) is dependent on dietary supply and can be enhanced through an increased intake of lutein and zeaxanthin. Kale, spinach, broccoli, lamb's lettuce and corn are good sources of both carotenoids. On average, we ingest 0.5 - 2 mg of lutein and about 0.2 - 1.8 mg of zeaxanthin every day. 10 mg of lutein is recommended daily for prevention or dietary treatment of eye diseases such as AMD. Up to 20 mg of lutein daily is considered safe.
We obtain most of our omega-3 fatty acids from rich sea fish. The recommended intake is currently being discussed internationally and is somewhere between 100 mg and 1 gram per day. Up to 3 grams a day is considered safe. The European Food Safety Authority (EFSA) recently stated that a 250 mg daily dose of the omega-3 fatty acid DHA is an important component in maintaining normal vision.
When one considers Germany's average fruit, vegetable and fish consumption (which needs to be improved greatly), it becomes clear that for many, especially older people, it is not easy to achieve the recommended daily intake values of the aforementioned micronutrients. Consequently, the experts recommend that older people take food supplements with these substances in nutritive doses. This generally means an amount that would be reached through an appropriate targeted food selection and amount.
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Schweigert FJ, Reimann J: Micronutrients and their importance to the eye - Effects of lutein/zeaxanthin and omega-3 fatty acids. On-line publication Klin Monatsbl Augenheilkd 28 May 2010 DOI: http://dx.doi.org/101055/s-0029-1245527
European Food Safety Authority (EFSA): Scientific Opinion Docosahexaenoic acid (DHA) related health claims EFSA Journal 2010;8(10):1734
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