Monday, April 28, 2008

Diet and Age-Related Macular Degeneration


A client asked for this information so thought I'd post it for you!

According to Dr. Max Snodderly, Ph.D., head of the laboratory at The Schepens Eye Research Institute in Boston, Massachusetts, an affiliate of Harvard Medical School, “Improved nutrition could help to retard the loss of visual sensitivity with age. Perhaps the gradual loss of vision in many older people is not an inevitable consequence of the aging process. ”

Age-related macular degeneration (AMD) is the leading cause of vision loss in people over the age of 55. Macular degeneration occurs when the macula (the central part of the retina responsible for sharp focus) is damaged. This damage causes permanent loss of central vision. Regular eye exams can detect the disease early on and laser treatments can slow down the central vision loss.

For most AMD cases, there’s no known cure or treatment. Symptoms of AMD include blurred or fuzzy vision, the illusion that straight lines, such as sentences on a page, are wavy and the appearance of a dark or empty area in the center of vision. Risk factors for the disease include cigarette smoking and family history of AMD. Exposure to sunlight, having light irises, and even being a woman seem to be additional risk factors.

Research shows that the consumption of fruits and vegetables containing two carotenoid (phytochemicals) pigments may be linked to a reduced risk for AMD. These carotenoids are lutein and zeaxanthin, primarily found in broccoli, corn and dark green vegetables like spinach and kale. Lutein and zeaxanthin are actually part of the retina of the eye. Increasing the concentration of these pigments in the eye may prevent vision loss.

Average lutein intake is 1-2 mg per day for American adults. Studies that have found improved visual function with lutein intake used a dosage of 10-15mg lutein. However, some researchers recommend lower levels, more in keeping with actual intakes, until the risks and benefits of these carotenoids are known. Studies done at Harvard University found that 6 mg per day of lutein lead to a 43% lower risk for macular degeneration.

Pharmaceutical companies have added the carotenoids to their dietary supplements but there is no definitive evidence about the safety and effectiveness of these supplements.

According to Linda Nebeling, Ph.D., R.D., of the National Cancer Institute, national data shows an overall decline in lutein & zeaxanthin intake, particularly in groups at greatest risk for age-related macular degeneration, as a result of a decrease in fruit and vegetable intake.

LUTEIN & ZEAXANTHIN CONCENTRATION IN FRUITS & VEGETABLES

Food

Per 100g

(mg)

Per Serving

(mg)

Serving size

Kale, raw

39.6

22.2

1 cup

Kale, cooked & drained

15.8

16.9

½ cup

Turnip greens, cooked & drained

8.4

9.0

½ cup

Collards, cooked & drained

8.0

8.7

½ cup

Spinach, cooked & drained

7.0

7.5

½ cup

Spinach, raw

11.9

6.7

1 cup

Broccoli, cooked & drained

2.2

1.7

½ cup

Corn, sweet, cooked & drained (not canned)

1.8

1.5

½ cup

Lettuce, Romaine, raw

2.6

1.5

1 cup

Peas, green, canned & drained

1.4

1.1

½ cup

Brussel sprouts, cooked & drained

1.3

1.0

½ cup

Corn, whole kernel, canned & drained

0.9

1.0

½ cup

Beans, snap green, cooked & drained

0.7

0.4

½ cup

Tangerine juice, fresh

0.2

0.3

¾ cup

Orange juice, unsweetened

0.1

0.3

¾ cup

Orange, Fresh

0.2

0.2

1 medium

The combination of antioxidants (vitamins C and E, and beta-carotene) and zinc, alone or with lutein, has also shown a modest benefit in reducing the risk for progression from moderate to advanced age-related macular degeneration and vision loss.

Food sources of Vitamin C include: broccoli, green and red peppers, collard greens, pineapple, strawberries, citrus fruits.

Food sources of Vitamin E include: Asparagus, avocado, nuts, olives, seeds, spinach and leafy greens, wheat germ, vegetable oils (corn, sunflower, soybean, cottonseed).

Food sources of beta-carotene include: Carrots, cantaloupe and other fruit and veggies with red, orange and yellow pigments.

Food sources of zinc include: Red meat, poultry, oysters, fortified cereals


Sources:

http://www.macular.org/nutrition/l_chart.html

Practice-Based Evidence in Nutrition http://www.dieteticsatwork.com/pen/

http://en.wikipedia.org/wiki/Macular_degeneration

http://www.hc-sc.gc.ca/iyh-vsv/life-vie/seniors-aines_vc-sv_e.html

http://jn.nutrition.org/cgi/content/full/136/10/2519

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