Posterior Segment Retina
Why the Lutein Source in Eye Vitamins Matters Diane E Alexander, PhD Technical Service Manager, Kemin Health, LC
Abstract
Eye care professionals are increasingly recommending eye vitamins to patients because a growing body of scientific evidence supports the benefits of good nutrition to reduce the risk for certain eye conditions and improve visual function. Eye care professionals expect that the eye vitamins they recommend will benefit the patients they serve. However, in order for ocular supplements to provide eye health benefits, the essential nutrients, including lutein, in eye vitamins should be bioavailable—so that they will be able to be delivered to the beneficial sites of action. Measurement of lutein and zeaxanthin in the macula via macular pigment optical density (MPOD) can help confirm the bioavailabilty of a lutein ingredient and indicate whether patients are getting enough lutein and zeaxanthin through their diet or supplementation regimen.
Keywords Lutein, zeaxanthin, macular pigment, macular pigment optical density (MPOD), age-related macular degeneration (AMD)
Disclosure: Diane E Alexander, PhD, is an employee of Kemin Health, LC. Received: December 9, 2010 Accepted: January 17, 2011 Citation: US Ophthalmic Review, 2011;4(1):86–9 Correspondence: Diane E Alexander, PhD, Technical Service Manager, Kemin Health, LC, 600 East Court Avenue, Suite A, Des Moines, IA 50309. E:
diane.alexander@
kemin.com
Support: The publication of this article was funded by Kemin Health, LC.
Carotenoids—Lutein and Zeaxanthin In general, carotenoids are yellow, orange, or red pigments that are soluble in lipids. Mammals utilize carotenoids for a variety of functions but are incapable of synthesizing them. Thus, carotenoids must be obtained solely from the diet. Of the 600 carotenoids found in nature, only dietary lutein and zeaxanthin are deposited in the macula. Meso-zeaxanthin is a compound derived from lutein that is also present in the macula—it is converted by the body from lutein rather than being introduced from dietary sources.
The lutein and zeaxanthin present together in the macula are known as macular pigment.1
The macular pigment appears as a yellow tint in
Figure 1. The intense deposition of the yellow-colored pigments in and around the fovea provided the basis for the clinical description of this area as the macula lutea or yellow spot. Lutein and zeaxanthin perform two primary functions in the macula. First, they filter high-energy, blue wavelengths of visible light as they enter the eye before they reach the photoreceptors.2
Lutein and zeaxanthin are found naturally together in vegetables such as spinach, kale, broccoli, corn, green peas, and green beans as well as other foods such as eggs.3,4
The bioavailability of lutein, unlike that of
many other nutrients, is enhanced by chopping and cooking the food. This is likely due to the disruption of the strong interaction between chlorophyll and lutein molecules. It is difficult, however, to obtain beneficial amounts of lutein and zeaxanthin from diet alone. Interventional studies report that 10mg of lutein (specifically FloraGLO® brand lutein) per day is effective in improving vision and reducing the risk for certain eye conditions.5
FloraGLO Lutein provides the same lutein
as is found naturally in vegetables and other foods but is obtained from marigold flowers through a patented process as shown in Figure 2.
The average daily intake of lutein and zeaxanthin in the US from diet alone is estimated to be less than 2mg,6
By passively absorbing these wavelengths, the macular pigment limits photo-oxidative damage to tissues that results from the reactive oxygen species (ROS) produced by these short wavelengths of light. Second, the macular pigment functions as an antioxidant to directly protect the retina from damage caused by ROS. The macular pigment also protects vulnerable photoreceptors from damage caused by sunlight, indoor lighting, and even light emitted from computer monitors. In other words, lutein and zeaxanthin act like internal sunglasses for the eyes. This protection not only helps to maintain healthy vision now but also helps to reduce the risk for certain eye conditions.
86 far below the 10mg per day
clinically reported to reduce the risk for certain age-related eye conditions and improve visual function. How can we bridge the gap? As discussed earlier, increased consumption of foods with high concentrations of lutein such as dark green leafy vegetables, corn, and eggs can help increase lutein intake to 10mg per day. However, for many individuals changing dietary habits is not a practical option, which is why supplementing one’s diet with lutein-fortified foods/beverages or eye vitamins containing FloraGLO is an easy, alternative way to bridge the dietary lutein gap. In fact, the FloraGLO Lutein found in ocular supplements has been shown to be approximately twice as bioavailable as the lutein in green vegetables, again due to the strong interaction between lutein and chlorophyll in leaves.7,8
© TOUCH BRIEFINGS 2011
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