Two "Minor" Carotenoids Provide Major Protection
Jarrow Formulas Lutein is a blend of lutein and zeaxanthin extracted from marigold pedals and then purified into crystalline form. These carotenoids (a family of brightly colored pigments in plant foods) are less common than their better-known relative, beta-carotene, but they appear to offer more and greater benefits to the body.
In particular, lutein and zeaxanthin have been shown clinically to support visual function and to protect the health of eye tissues as we age. In addition, preliminary research suggests that lutein and zeaxanthin may protect the cardiovascular system and maintain normal cell differentiation in the tissues of the breast, cervix, colon and skin.
The eyes are especially prone to certain types of oxidative damage. Age-related macular degeneration (AMD) is a typical result of the aging process, as is the formation of cataracts.
Prevent Blindness America estimates that AMD may affect 13 million individuals in this country. Cataracts impair the vision of roughly 4 million Americans. Some authorities estimate that thirty percent of all adults aged 70 and older suffer from some form of vision impairment. Diet may play a significant role in these age-related degenerations. In one study of 40 to 70 year olds, for instance, those who consumed fewer than 3.5 servings of fruits and vegetables per day had 5 times the risk for developing one type of cataract and 13 times the risk for developing another type of cataract when compared to those who ate more than 3.5 servings daily.
What Are Lutein and Zeaxanthin?
Lutein and zeaxanthin are important antioxidants used by the body for a number of physiological functions. Lutein is a carotenoid which does not supply Vitamin A activity in the body. It is chemically distinctive in that it lacks part of the terminal "ring" structure of the other carotenoids.
Like its close relative zeaxanthin, lutein is what is termed a xanthrophyll carotenoid. Both of these related carotenoids are better antioxidants than the beta-carotene under normal oxygen conditions. Lutein is the more important of the two.
According to the March 2000 issue of Optometry (the journal of the American Optometric Association), "Lutein can be metabolized into zeaxanthin and is therefore the more essential carotenoid." Zeaxanthin has been shown to be present in the center of the macula. Lutein and zeaxanthin are usually found together in leafy green vegetables, such as kale, broccoli, spinach and mustard greens.
One of the primary functions of lutein and zeaxanthin is to provide protection against oxidative and free radical damage. These yellow-colored carotenoids are found in high concentrations within the macula lutea (the yellow spot in the center of the retina) and in smaller amounts throughout the retina and the eye lens. They are also concentrated in the skin, breast and cervical tissues. These stores, however, appear to diminish with age if not regularly replenished through dietary means.
Lutein/Zeaxanthin and AMD
Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in people over age 65. The exact cause of AMD is not yet known, although the protective role of nutrition against the condition is being researched at major universities and other institutions. A 1994 study published in the Journal of the American Medical Association concluded that a daily intake of 6 mg per day of lutein led to a 43% lower risk of developing AMD.
Scientists believe that lutein and zeaxanthin contribute to the density of macular pigment - the component of the eye which typically absorbs and filters out 40 to 60% of damaging near-ultraviolet blue light (near-UV light) which strikes the retina. The denser the pigment, the more the inner retina is protected from light-induced damage. Lutein/zeaxanthin also helps limit blue light damage to the inner retina by inhibiting lipid peroxidation and by neutralizing free radicals.
Lutein/Zeaxanthin and Health of the Eye Lens
Considerable evidence shows the importance of lutein and zeaxanthin in reducing changes in the opacity of the eye lens as we age. A study published in the British Medical Journal examined cataract formation among 50,000 women over an eight-year period. The results clearly showed that the consumption of spinach, which is an excellent source of lutein and zeaxanthin, led to a much lower level of such eye lens changes than did the consumption of other vegetables, such as carrots, sweet potatoes and winter squash, which contain primarily beta-carotene and very little lutein.
Similarly, according to a study published in the Journal of the American Medical Association, people who eat foods rich in lutein - particularly kale and spinach - are less likely to develop macular degeneration. The intake of carotenoids other than beta-carotene, that is, alpha-carotene, lutein and lycopene, has been inversely correlated with the risk of developing cataracts. In other words, the more alpha-carotene, lutein and lycopene consumed, the lower the incidence of cataracts.
Protection most likely comes from the scavenging of free radicals. Oxidative/free radical damage to the eye lens is believed to play an important part in the development of cataracts. Lutein/zeaxanthin prevents peroxidation in the lens, thus limiting damage to the opacity of this tissue. However, there is no evidence that lutein/zeaxanthin can help to reverse an existing cataract.
Lutein/Zeaxanthin and Cardiovascular Health
As is true of Vitamin E, but not of other carotenoids, lutein is found in blood plasma at levels correlated with the amount of cholesterol. Tests suggest that although lutein is relatively minor as a component of LDL cholesterol in comparison with Vitamin E, its antioxidant protective effects may be ten times greater if compared on a one-to-one basis.
Some researchers suggest that this may provide another clue to the so-called "French Paradox" in which the consumption of large amounts of saturated fats has not led to elevated rates of heart disease among the French. One study compared the level of antioxidants and carotenoids in residents of Toulouse, France with that of residents of Belfast, Northern Ireland. The Belfast residents are now to have a higher incidence of coronary heart disease than do their French counterparts. ToulouseBelfastToulouse residents than the Belfast residents. residents had lutein serum levels which were two times higher than those found in the residents. Significantly, just as lutein is associated with higher high-density lipoprotein cholesterol (HDL) serum levels (HDL is the "good cholesterol" which transports cholesterol out of the arteries and back to the liver for disposal), so too were the HDL levels higher in the
Lutein/Zeaxanthin and Regulated Cell Growth
Several studies have indicated that lutein and zeaxanthin may be helpful in preventing irregular cell growth in various tissues of the body, such as the skin, breast, cervix and larger intestine. A 1999 Harvard epidemiological study indicated that lutein is one of the nutrients which are associated with better breast health. A study published in the American Journal of Clinical Nutrition found a similar positive association between the consumption of lutein and colon health. Lutein, like lycopene and a number of other carotenoids, would appear to influence the inner regulation of cell growth and repair. Source: Jarrow Formulas
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Scientific References
Jacques, PF, Chylack LT Jr. Epidemiologic evidence of a role for the antioxidant vitamins and carotenoids in cataract prevention. Am J Clin Nutr. 1991 Jan; 53(1 Suppl):352S-355S.
Seddon JM, Ajani UA, Sperduto RD, Hiller R, Blair N, Burton TC, Farber MD, Gragoudas ES, Haller J, Miller DT, et al. Dietary carotenoids, Vitamins A, C, and E, and advanced age-related macular degeneration. Eye Disease Case-Control Study Group. JAMA. 1994 Nov 9:272(18):1413-20.
Johnson EJ, Hammond BR, Yeum KJ, Qin J, Wang XD, Castaneda C, Snoodderly DM, Russell RM. Relation among serum and tissue concentrations of lutein and zeaxanthin and macular pigment density. Am J Clin Nutr. 2000 Jun; 71(6):1555-62.
Hankinson SE, Stampfer MJ, Seddon JM, Colditz GA, Rosner B, Speizer FE, Willett WC. Nutrient intake and cataract extraction in women: a prospective study. BMJ. 1992 Aug 8; 305(6849):335-9.
Seddon JM, Ajani UA, Sperduto RD, Hiller R, Blair N, Burton TC, Farber MD, Gragoudas ES, Haller J, Miller DT, et al. Dietary carotenoids, Vitamins A, C, and E, and advanced age-related macular degeneration. Eye Disease Case-Control Study Group. JAMA. 1994 Nov 9:272(18):1413-20. Jacques PF. The potential preventative effects of vitamins for cataracts and age-related macular degeneration. Int J Vitam Nutr Res. 1999 May: 69(3):298-205.
Mares-Perlman JA, Brady WE, Klein BE, Klein R, Haus GJ, Patta M, Ritter LL, Shoff SM. Diet and nuclear lens opacities. Am J Epidermiol. 1995 Feb 15:141(4):322-34.
Howard AN, Williams NR, Palmer CR, Cambou JP, Evans AE, Foote JW, Marques-Vidal P, McCrum EE, Ruidavets JB, Nigdikar SV, Rajput-Williams J, Thumham DI. Do hydroxy-carotenoids prevent coronary heart disease? A comparison between Belfast and Toulouse. Int J Vitam Nutr Res. 1996:66(2):113-8.
Smith-Warner SA, Elmer PJ, Tharp TM, Fosdick L, Randall B, Gross M, Wood J, Potter JD. Increasing vegetables and fruit intake: randomized intervention and monitoring in an at-risk population. Cancer Epidermiol Biomarkers Prev. 2000 Mar; 9(3):307-17.
Slattery ML, Benson J, Curtin K, Ma KN, Schaeffer D, Potter JD. Carotenoids and colon cancer. Am J Clin Nutr. 2000 Feb; 71(2):575-82.
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