Lutein: An Essential Nutrient for Eye Health
Antinyctalopic, Antioxidant, Antitumor, and Antiatherosclerotic
Jul 6, 2009
Macular degeneration - the deterioration of the macula (a small yellowish central area of the retina - the membrane covering the back wall of the eyeball) - is the leading cause of blindness in persons over 60 years of age around the world.
Numerous epidemiological studies have linked age-related macular degeneration (AMD) with low intake of foods rich in lutein, a yellow pigment that belongs to the xanthophyll class of the carotenoid family.
Physical Characteristics of Lutein
Lutein (C40 H56 O2) is:
- a fat-soluble carotenoid alcohol, soluble in solvent such as alcohol, acetone, etc. It is insoluble in water.
- yellow in color. It is called lutein - Latin for yellow or "lutea." It was isolated from eggyolks in 1912 by Statter and Escher.
- Lutein and zeaxanthin, its isomer Lycopene or Rhodopurpurin are the only carotenoids present in the eye's macula (See figure below).
Physiological Functions of Lutein
Lutein (and its isomer - zeaxanthin) absorbs and filters blue light which is damaging to the retinal pigment epithelium (RPE). The Retinal Epithelium Pigment is the cell layer that nourishes the retinal cells. Since lutein and zeaxanthin accumulates in the spot between incoming light and the photoreceptor cells, they are perfectly positioned in attenuating blue light from reaching and destroying the underlying photoreceptor cells. Developmental Opthalmology 2005
- It protects the retina by minimizing the damaging effects of oxygen to the tissues as a result of normal metabolism and light. Light damages the retina by generating highly reactive and unstable molecules that attack tissue and substances that contain lipid or fat.
- Animal studies show that subjects given a diet rich in lutein developed less retinal degeneration. Long-term human studies show that people with light-colored irises are at a higher risk for AMD and are more likely to have a lower macular pigment density for lutein and zeaxanthin.
- Smoking increases the risk for AMD.
- It helps prevent nyctalopia (night-blindness) or inability to see in low light.
Significant Food Sources of Lutein
- Kale - 1 cup chopped raw (67 g) contains: 21,954 micrograms (mcg) of lutein
- Mustard Greens - 1 cup raw (56 g) contains: 5,544 micrograms
- Radicchio - 1 cup (40 g) contains: 3,533 micrograms
- Collard Greens - 1 cup chopped raw (36 g) contains: 3,216 micrograms
- Green Peas - 100 grams contains: 2,477 micrograms lutein
- Zucchini or any summer squash - 1 cup raw sliced (113 g) contains: 2.401 micrograms
- Watercress - 1 cup raw (34 g) contains: 1,961 micrograms
- Leeks -1 cup raw, green tops and white stem (89 g) contains: 1,691 micrograms
- Corn ( 1 medrium, sweet yellow): 688 micrograms
- Romaine Lettuce (1 large outer leaf -28 grams): 547 micrograms
- Okra - 1 cup raw (100 g) contains: 516 micrograms
- Asparagus - 1 large spear, 71/2 - 8" or 28 grams contains: 142 micrograms
- Egg yolk ( 1 large, 17 grams) contains: 186 micrograms
References
Hubert Greenway & Steven G. Pratt "Fruit and Vegetables in Diseases of the Eye" Vegetables, Fruits and Herbs in Human Health Promotion. ed. Ronald R. Ross, CRC Press 2001
Stahl W. "Macular Carotenoids" Developmental Opthalmology 2005;38:70-88
Moeller SM et al. "The Potential of the Role of Dietary Xanthopylls in Cataract and Age-Related Macular Degeneration." J Am. College of Nutrition 2000;19(90005):522S-527S)
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