Carotenoids are phytochemicals (chemicals found in plants) commonly
found in certain fruits and vegetables that provide the red, orange and
yellow colors of these foods. Lutein and zeaxanthin are found primarly
in broccoli, corn, squash and dark green leafy vegetables like spinach
and kale.
“Women in the United States have decreased their consumption of
vegetables like corn, green beans, broccoli, spinach, carrots and winter
squash, ” said Dr. Nebeling. “These vegetables are rich sources of
carotenoids and other important nutrients. Consuming too little of
these foods could lead to an increased risk of disease.
Egg yolk and yellow corn contain the highest mole percentage (% of
total) of lutein and zeaxanthin (more than 85% of the total
carotenoids). Yellow corn was the vegetable with the highest quantity
of lutein (60% of total) and orange pepper was the vegetable with the
highest amount of zeaxanthin (37% of total). Substantial amounts of
lutein and zeaxanthin (30-50%) were also present in kiwi fruit, grapes,
spinach, orange juice, zucchini, and different kinds of squash. The
results show that there are fruits and vegetables of various colors with
a relatively high content of lutein and zeaxanthin.
Most of the dark green leafy vegetables, previously recommended for a
higher intake of lutein and zeaxanthin, have a 15-47% of lutein, but a
very low content (0-3%) of zeaxanthin. This study shows that fruits and
vegetables of various colors can be consumed to increase dietary intake
of lutein and zeaxanthin.
Dr. Johanna M. Seddon and her associates at Harvard University(3.)
found that 6 mg per day of lutein lead to a 43 percent lower risk for
macular degeneration. Half a cup of cooked kale contains 10.3 mg of
lutein while one-half a cup of cooked spinach provides 6.3 mg.
The Schepens Eye Research Institute 1998 study concluded that vision
loss associated with aging maybe preventable - even reversible - through
improved nutrition. Although visual sensitivity decreases with age,
this process need not be inevitable.
In that study, D. Max Snodderly, Ph.D., head of the laboratory at The
Schepens, concluded that dietary factors associated with macular
pigment appear to protect the retina from loss of sensitivity. Dark
green and orange plants and fruits, like spinach, broccoli, green beans,
corn and peaches, are especially effective.
In The Schepens study, older subjects with high macular pigment
density retained their youthful visual function. Increasing macular
pigment density may slow, or possibly even reverse, the progression of
the disease. Thus one can understand the importance of pursuing the
right nutritional program.
Nutrition and Macular Degeneration
Many researchers and eye care practitioners believe that certain nutrients — zinc,
lutein,
zeaxanthin and vitamins A, C and E — help lower the risk for AMD or
slow down the progression of dry macular degeneration. Benefits of high
levels of
antioxidants
and zinc for halting or slowing development of macular degeneration
have been widely reported based on results released in 2001 from the
Age-Related Eye Disease Study (AREDS) conducted by the National Eye
Institute.
Phase two of the AREDS study began in late 2005 to evaluate whether
similar protective effects against AMD might be associated with other
nutrients such as
omega-3 fatty acids or "good fats," and lutein and zeaxanthin found in green, leafy vegetables.
Archives of Ophthalmology reported findings in August 2001
that consumption of omega-3 fatty acids, which are particularly
prevalent in cold-water fish, also had a protective effect against
advanced macular degeneration. Meanwhile, consumption of omega-6 fatty
acids, prevalent in vegetable oils, was associated with an increased
risk of developing AMD.
Research has now suggested that the development of AMD is linked to a
depleted level of macular pigment. This retinal layer efficiently
filters out harmful blue wavelengths of light, and also reduces the
amount of free radicals, which are compounds found in high
concentrations in the macular area and can cause oxidation of cell
membranes.
3 It is theorized that certain antioxidant
compounds reduce the effect that these free radicals have on the macular
pigment, and consequently may have an impact on the development of AMD.
4,5,6 These antioxidants have demonstrated their
effectiveness in building and maintaining the thickness of the retinal
pigment layer, and are known as carotenoids, a family of colored
compounds found in fruits and vegetables. Beta-carotene is an example of
a carotenoid; altogether we consume and utilize fourteen different
carotenoids in our diet. Two other carotenoids were found to have
effectivity in the retinal pigment layer. Lutein and zeaxanthin are
carotenoids found in many vegetables and fruits; they are found in the
highest concentration in dark, leafy green vegetables such as spinach,
collard greens, and kale. Studies have shown that a diet high in these
materials have some effect on delaying the advancement of AMD.
7,8,9,10
The use of synthetic supplements that contain these carotenoids, along
with the vitamins C, E, and zinc, have been proven to be an effective
means of limiting the disease in patients with advanced signs and
symptoms of AMD.
11
The use of antioxidants cannot reverse the damage caused by AMD;
however, its use may prevent or slow the progression of AMD in certain
patients. If dietary supplementation of antioxidants taken along with
Vitamins C, E, and zinc is undertaken, this therapy may be most
appropriate for individuals who:
- Show early evidence of AMD
- Are over 50 years of age
- Have family history of AMD
- Receive insufficient dietary intake of vitamins and minerals
Eleven Steps To Help Prevent Macular Degeneration
Here are guidelines to help prevent or slow the progression of AMD:
- Don't smoke. Period.
- Eat plenty of dark, leafy green vegetables, such as raw spinach. Just a half cup of raw spinach three times a week is good.
- Take a multivitamin/multimineral supplement, such as Centrum Silver, unless your doctor advises otherwise.
- If you already have AMD, ask your doctor about one of the AREDS formulations, such as Alcon I-Caps, Bausch + Lomb Ocuvite PreserVision or ScienceBased Health MacularProtect Complete.
- Eat fish or take a fish oil
supplement. I recommend taking two enteric-coated fish oil capsules
every day on days you don't eat fish. Why enteric-coated? Because it's
designed to help the capsule pass through your stomach unaltered until
it finally breaks apart in the intestines; that way, you won't belch up
that fishy taste!
- Exercise regularly, and stay at a healthy weight.
- Eat fruit and nuts daily.
- Reduce refined carbohydrates (high-glycemic index foods).
- Keep your blood pressure and cholesterol under control. Regular
exercise and weight control can help manage your blood pressure and
cholesterol.
- Wear appropriate sunglasses outdoors to block UV and blue light that may cause eye damage.
- Have regular eye exams.
“Scientific studies over the past 10 years show benefits from vinegar
consumption,” says Carol Johnston, Ph.D., head of the nutrition
department at Arizona State University, Tempe. Vinegar decreases both
fasting and postprandial (after-meal) glucose levels, she says. “It’s
inexpensive and can be easily incorporated into the diet. Used in
combination with 