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TREATMENT OF
MACULAR DEGENERATION
 
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CAROTENOIDS

carrots and peasCarotenoids are the natural pigments that give color to egg yolks, tomatoes, green leaves, fruits, and flowers. They cannot be made internally in the body and therefore must be obtained from the diet. Carotenoids are naturally coloring and stabilizing agents. Foods that contain carotenoids retain their appearance for long periods and withstand the action of direct sunlight.

Lutein and zeaxanthin are members of the carotenoid family, a family best known for another one of its members, beta-carotene (see Beta-Carotene). They serve as accessory light-gathering pigments and to protect these organisms against the toxic effects of ultra-violet radiation and oxygen. They also appear to protect humans against phototoxic damage. Lutein and zeaxanthin are found in the macula of the human retina, as well as the human crystalline lens. They are thought to play a role in protection against age-related macular degeneration (ARMD) and age-related cataract formation. They may also be protective against some forms of cancer. These two carotenoids are sometimes referred to as macular yellow, retinal carotenoids or macular pigment.

Lutein and zeaxanthin, which are naturally present in the macula of the human retina, filter out potentially phototoxic blue light and near-ultraviolet radiation from the macula. The protective effect is due in part, to the reactive oxygen species quenching ability of these carotenoids. Further, lutein and zeaxanthin are more stable to decomposition by pro-oxidants than are other carotenoids such as beta-carotene and lycopene. Zeaxanthin is the predominant pigment in the fovea, the region at the center of the macula. The quantity of zeaxanthin gradually decreases and the quantity of lutein increases in the region surrounding the fovea, and lutein is the predominant pigment at the outermost periphery of the macula. Zeaxanthin, which is fully conjugated (lutein is not), may offer somewhat better protection than lutein against phototoxic damage caused by blue and near-ultraviolet light radiation.

Lutein and Zeaxanthin, which are the only two carotenoids that have been identified in the human lens, may be protective against age-related increases in lens density and cataract formation. Again, the possible protection afforded by these carotenoids may be accounted for, in part, by their reactive oxygen species scavenging abilities.

The chemical structures of Lutein and Zeaxanthin are illustrated below.

LUTEIN MOLECULE (SINGLE STRANDED RINGS) lutein molecular structure

 

ZEAXANTHIN MOLECULE (ONE DOUBLE-STRANDED BOND IN EACH RING)zeaxanthin molecular structure

Lutein and Zeaxanthin are far more effective in penetraing the retina than is beta-carotene. However, AREDS did not include them, and substituted beta-carotene, because Lutein and Zeaxanthin were not commercially avaialble at the time of the study. However, AREDS2 will include these compounds.

Products tthat already include Lutein and Zeaxanthin in their most advanced formulas include:

Vitamin Science - VisiVite i-Defense Gold and Green Formulas

 

SCIENTIFIC LITERATURE:

Berendschot TT, Goldbohm RA, Klö pping WA, et al. Influence of lutein supplementation on macular pigment, assessed with two objective techniques. Invest Opthalmol Vis Sci. 2000; 41:3322-3326.

Bone RA, Landrum JT, Dixon Z, et al. Lutein and zeaxanthin in the eyes, serum and diet of human subjects. Exp Eye Res. 2000; 71:239-245.

Bone RA, Landrum JT, Tarsis SL. Preliminary identification of the human macular pigment. Vision Res. 1985; 25:1531-1535.

Handelman GJ, Nightingale ZD, Lichtenstein AH, et al. Lutein and zeaxanthin concentrations in plasma after dietary supplementation with egg yolk. Am J Clin Nutr. 1999; 70:247-251.

Landrum JT, Bone RA, Joa H, 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.

Nussbaum JJ, Pruett RC, Delori FC. Historic perspectives. Macular yellow pigment. The first 200 years. Retina. 1981; 1:296-310.

van het Hof KH, Brouwer IA, West CE, et al. Bioavailability of lutein from vegetables is 5 times higher than that of beta-carotene. Am J Clin Nutr. 1999; 70:261-268.