EYE HEALTH

in industrialized countries, including the United States, AMD is the leading cause of blindness and has limited treatment

options in people older than 65.1 In normal vision, the eye’s lens

collects light and focuses it on the retina, formulating an image that the brain can process. 

When the lens becomes oxidized through genetic factors or environmental damage such as oxidative stress, excessive light exposure, or smoking, it can become cloudy, resulting in cataracts.2 Likewise, the macula, the portion of the retina responsible for

central vision, can be damaged through similar environmental factors and/or with age, especially in those 50 and older, causing the center of the visual field to appear blurry or dark.2,3 While the latter risk factors are relatively well known, awareness of the role nutrition plays in eye health is growing as well, with lutein emerging as a star player.1,3 Other nutrients that support eye health include dietary

omega-3 polyunsaturated fatty acids, beta-carotene, vitamins C and E, zinc, and copper.4

LUTEIN

An Underrecognized Antioxidant That Can Help Preserve Sight

By Ginger Hultin, MS, RDN, CSO Eye health has a unique and direct link to nutrition status.

Critical sensory organs, the eyes require specific nutrients for protection and functionality. Many nutrients help support eye health, but carotenoid antioxidants in particular continue to surface as among the most essential. 

The carotenoid lutein protects the eye’s macula, both shielding damage from light and supporting better vision.1 While lutein commonly is sold in eye health supplements or added to supplemental eye health formulas, it’s also found in an array of healthful foods. Dietitians play a unique role in their ability to provide guidance for patients on how to eat to maintain eye health.

Role of Nutrients Visual impairment is a major and debilitating health concern worldwide. According to the World Health Organization

report on visual impairment in 2010, globally cataracts accounted for 33% of vision loss; age-related macular degeneration (AMD) and diabetic retinopathy each were responsible for 1%. Leading causes of blindness on a global scale have similar proportions; cataracts are the most common at 51% of cases, followed by glaucoma at 8% and AMD at 5%. However,

What Is Lutein?

Lutein is a xanthophyll, a yellow/brown carotenoid pigment;

in conjuncture with its related antioxidant zeaxanthin, it’s been

extensively studied and determined to help delay the onset of

cataracts and AMD.1,3,5 Lutein and zeaxanthin are stereoisomers,

meaning they differ only in the spatial arrangement of their atoms, and often are found in the same foods. The body can’t manufacture lutein, so it must be consumed in the diet.2 Studies estimate that the standard American diet contains 1 to 3 mg per day of lutein and zeaxanthin, while 6 mg daily is needed to reduce the risk of AMD.1,6

Once consumed, lutein and zeaxanthin are transported in the blood stream and deposited into the retina (especially into the macula); they’re the only carotenoids to do so.1,2,7 High concentrations of lutein and zeaxanthin in the retina absorb up to 90% of blue light, helping protect the macula from damage and maintain optimal vision.8 Furthermore, there’s evidence that lutein in the macula may improve visual acuity and help protect the eyes from free radical

damage, with the strongest evidence demonstrating a delay

in cataract and AMD onset.1

Aside from eye health, lutein also may be useful in treating diabetes and CVD, improving cognitive function, and preventing cervical, breast, esophageal, prostate, lung, and colon cancers. However, the most convincing evidence of lutein’s efficacy is for the management of eye health, and more studies are needed to explore its uses for other

health conditions.5

Dietary Sources

There are many food sources of lutein, including green veggies

(eg, parsley, spinach, kale, broccoli, lettuce, peas, Swiss chard), egg yolk, and whole grains (eg, einkorn, corn, durum wheat).1 Although there are no recommended daily intakes set for lutein, 10 mg in supplement form has been shown to possibly support eye health, a level that’s easily achieved through food sources (just 1 cup cooked dark leafy greens provides well over 10 mg lutein, with cooked kale providing almost 24 mg).2 In one study, older adults who consumed one whole egg per day experienced a 26% increase in serum lutein (p<0.001) after five weeks compared with placebo.9

The American Optometric Association recommends meeting

needs through food or supplements,2 but food sources may be better absorbed.5 Another consideration is that lutein in eggs may be more bioavailable than that in plant sources.5

Lutein, along with other carotenoids, is best absorbed when consumed with a fat source, so preparing lutein-containing foods with oil, avocado, or nuts and seeds, for example, may increase bioavailability.8