The cataract-macular degeneration connection
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The cataract-macular degeneration connection

According to the National Institutes of Health, the leading causes of vision impairment and blindness in the United States are directly due to age-related eye diseases, namely cataracts and macular degeneration.

Cataracts are the leading form of blindness. A cataract is a clouding of the normally clear lens of the eye. As a cataract forms, the lens becomes more and more yellow and opaque.

Age-related macular degeneration (also known as macular degeneration or AMD) affects more 13 million men and women over age 50. A person suffering from AMD typically loses central vision, but maintains peripheral vision.

AMD is characterized by a dark spot in the middle of your macula—a yellow-hued spot in the middle of your retina that is responsible for central vision and allows you to see fine details. This is critical for a couple of reasons.

First, the yellow tinge of the macula is due in large part to two nutrients that accumulate in the eye: lutein and zeaxanthin. As researchers from the Massachusetts Eye and Ear Infirmary in Boston discovered, people who ate a diet high in these particular nutrients had a significantly reduced risk for AMD.1

A similar study from Japan found that 6 mg of lutein provided a significant increase in contrast sensitivity as well as retinal sensitivity.2 And yet another study found that increased intake of lutein and zeaxanthin resulted in a statistically significant increase in central macular pigment optical density, leading researchers to conclude that macular pigment may confer protection against macular degeneration.3

Cataract as AMD protector?

So what does this have to do with cataracts? Turns out, the yellow-hued, carotenoid-rich macula also works to absorb excess blue and ultraviolet light, making it a natural sunblock, if you will, for your eyes.

However, if you are deficient in lutein and zeaxanthin due to natural aging as well as poor lifestyle choices, your macula loses more and more yellow pigment, making it increasingly difficult to filter out blue light as effectively, which in turn makes it less able to offset damage from the blue light.

Next thing you know, you are at increased risk for AMD—and cataracts.

According to German researchers, your body may have a rather peculiar way of compensating for this lack of yellow pigments.4 It forms a cataract.

Yes, a cataract.

If you think about it, it makes sense. Lutein and zeaxanthin are yellow pigments that help filter out blue light. In their absence, your body needs to find another yellow substance to do the same job, so it yellows the lens itself and thickens it in an attempt to protect the retina.

Therefore, high intake (and hence high retinal concentration) of lutein and zeaxanthin help protect the retina. This not only reduces your risk of AMD, but also lessens the need for a cataract to develop in the first place.

Feed your macula

There are a couple of ways to ensure you get the lutein and zeaxanthin your eyes crave for optimal health. The first (and tastiest!) is to increase your intake of foods that contain these nutrients. This means loading up on green, yellow, and orange foods such as egg yolks, green leafy vegetables, red and green peppers, carrots, corn, tomatoes, broccoli, and basically any brightly colored vegetable you lay your eyes on.

If you prefer the supplement route, studies have shown that you can take 20 mg of lutein a day for up to six months with no adverse effects.5 For zeaxanthin, aim for 1-2 mg of daily.

Sources

  1. Seddon JM, 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.
  2. Sasamoto Y, et al. Effect of 1-year lutein supplementation on macular pigment optical density and visual function. Graefes Arch Clin Exp Ophthalmol. 2011 Aug;249(12):1847-54.
  3. Connolly EE, et al. Supplementation with all three macular carotenoids: response, stability and safety. Invest Ophthalmol Vis Sci. 2011 Nov:52(12):9207-17.
  4. Wegner A and Khoramnia, R. Cataract is a self-defence reaction to protect the retina from oxidative damage. Medical Hypotheses. 2011 May;76(5):741-4.
  5. Aleman TS, et al. Macular Pigment and Lutein Supplementation in Retinitis Pigmentosa and Usher Syndrome. Invest Ophthalmol Vis Sci. 2001;42:1873‐81.

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