ANOTHER REASON TO EAT YOUR VEGETABLES
Have you ever heard of age-related macular degeneration? Probably not, unless you, a relative, or a friend have it. Macular degeneration affects more than 10 million Americans and is the leading cause of irreversible blindness among persons older than 65 years. Currently, there is no effective treatment for macular degeneration, and little information is available on its prevention. An exciting recent study suggests that eating dark green leafy vegetables like spinach, collard greens, and kale could reduce risk of macular degeneration.
Joanne Seddon, M.D., and co-investigators examined more than 350 older adults with macular degeneration. Their diets were compared with those of 520 adults without macular degeneration. The most promising results were those related to the carotenoids. (Carotenoids are substances like beta-carotene which are found in foods.) Those subjects with the highest intakes of dietary carotenoids had a 43% lower risk for macular degeneration compared with those with the lowest intakes of carotenoids. When specific carotenoids were examined, two carotenoids, lutein and zeaxanthin, were most strongly associated with reduced risk of macular degeneration. Until recently, it was not possible separately to analyze lutein and zeaxanthin; so they are usually listed together in food composition tables.
Dark green leafy vegetables are especially good sources of lutein. Subjects with the lowest risk of developing macular degeneration ate an average of 5757 micrograms of lutein/zeaxanthin daily. This is the equivalent of about 1/4 cup or less of cooked kale, collard greens, or spinach. Table 1 provides amounts of lutein/zeaxanthin in commonly eaten foods and can be used to assess your intake of these carotenoids. The investigators examined specific foods and found that eating spinach or collard greens (1/2 cup 5 or more times per week) was associated with an 86% lower risk for macular degeneration compared with eating those greens less than once a month.
Use of vitamin supplements (vitamin A, vitamin C, or vitamin E) was not associated with reduced risk of macular degeneration. The authors recommend increasing the consumption of dark green, leafy vegetables to reduce risk of developing macular degeneration.
Seddon JM, Ajani UA, Sperduto RD, et al. Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. JAMA 1994;272: 1413-1420.
Mangels AR, Holden JM, Beecher GR, et al. Carotenoid content of fruits and vegetables: An evaluation of analytic data. J Am Diet Assoc 1993;93:284-296. Table 1: Lutein and/or Zeaxanthin in foods 1/2 cup cooked kale
14,235 mcg(*) 1/2 cup cooked collard greens 13,855 mcg 1/2 cup cooked spinach
11,970 mcg 1/2 cup cooked Swiss chard
9,680 mcg 1/2 cup cooked mustard greens 7,425 mcg 1 cup chopped red pepper
6,800 mcg 1 cup raw spinach
5,712 mcg 1/2 cup cooked beet greens
5,544 mcg 1/2 cup cooked okra
5,440 mcg 1 cup romaine lettuce
3,192 mcg (*)mcg=microgram (1/1,000,000th of a gram)
The Vegetarian Resource Group, Inc.
By Reed Mangels