One of the scary things about age-related macular
degeneration, the leading cause of vision loss in older
people, is that there is often little that can be done to
slow down the disease.
But a combination of dietary supplements, which includes high
levels of antioxidants and zinc, may help preserve the sight
of people with age-related macular degeneration (AMD). And
while studies have not yet proven that this supplement
combination prevents AMD, some ophthalmologists recommend it
to people who are at risk for this eye condition, such as
those with a parent or sibling and those with fair skin and
blue eyes.
AMD is a disorder of the macular, the central part of the
retina, that makes vision less sharp and affects the ability
to see straight ahead. There are two forms of the disease,
dry and wet. The dry form is more common than the wet form
and involves a more gradual loss of vision. In the early
stage of the dry form of disease, someone will have several
yellow deposits, called "drusen," on the macula. Intermediate
AMD is marked by medium-sized drusen or one or more large
drusen. And advanced AMD involves the breakdown of cells and
tissue in the central retina. The "wet" form of AMD occurs
when new blood vessels form behind the retina and start to
grow toward the macula and leak or bleed into the eye.
Do dietary supplements slow the progression of AMD?
We know from a very good National Eye Institute (NEI)-
sponsored study, called the Age-Related Eye Disease Study
(AREDS), that a certain combination of nutritional
supplements retards the progress of macular degeneration. In
the 10-year study, the supplements slowed the progress of the
disease by about 25 percent in people with intermediate AMD
or AMD in one eye but not the other eye. The study did not
show whether or not the supplements made a difference to
people who don't have macular degeneration or who have early
AMD. So one can't say, "You should definitely take these if
you are at risk for macular degeneration." However, it only
makes sense that antioxidant supplements, in moderate
amounts, are likely to make a difference in terms of
prevention. But remember it is not proven, so it's your
choice.
What supplements are recommended?
The recommended dietary supplement contains five ingredients.
Four of them are functional and one of them is there as an
add-on. The four are vitamin C, 500 mg; vitamin E, 400 mg;
beta-carotene, 25,000 international units (I.U.), and zinc,
80 mg. 2 milligrams of copper is also in there, because zinc
can cause a copper deficiency. For those who do not have AMD
but are at risk, one would recommend only half of that amount
of zinc, and for those who are smokers, less or no beta-
carotene.
How does this combination of dietary supplements keep the
eye healthy?
The leading theory about macular degeneration is that free
radicals are damaging the macula, which is the central part
of the retina. Free radicals are little molecules that are
produced normally just by breathing oxygen. One thinks of
them as electrically charged, and they have to have a partner
right away to be neutralized. The way they get neutralized is
by antioxidants, and the vitamins serve as antioxidants.
With macular degeneration, either one has too many free
radicals or one doesn't have enough antioxidants. Beyond the
amount that you produce just by breathing oxygen, free
radicals are produced by air pollution, herbicides,
pesticides, smoke and sunlight. In the last 50 years, we have
been pumping many of those things into our air, water, soil
and food, and the ozone layer is thinner, so we're all
getting hit with more sunlight. So we have a bigger load of
free radicals.
On the antioxidant side, one has to get antioxidants from
food. We don't make our own. But over the same 50 years,
we've changed how we grow food. We grow food in big
industrial farms in demineralized soil, we don't rotate
crops, and we spray them with herbicides and pesticides. So
the thought is that there is less actual antioxidant power in
the food, so one needs supplements to counteract the extra
load of free radicals.
Are these doses of antioxidants unsafe for some
people?
The only safety consideration has been beta-carotene in
smokers because it increases lung cancer risk. Of course, not
smoking is a cardinal rule of macular degeneration because it
increases risk. So if you have macular degeneration, or are
at high risk for it, and you're smoking, you're really
inviting it.
Can lutein reduce risk of AMD?
It is often suggested that people add the carotenoid lutein
and the antioxidant selenium, though there is no proof that
they decrease risk. There was a good study out of Harvard in
1994 indicating that people who ate five servings or more of
green, leafy vegetables that were rich in carotenoids had 42
percent less macular degeneration. So there is reason to
believe that lutein might be a good contributor to this
antioxidant formula. The amount of lutein recommended runs
from 6 mg to 20 mg. Six milligrams is the amount that would
be in, for instance, a serving of dark green, leafy
vegetables.
* The National Eye Institute is currently studying lutein and
zeaxanthin, and a randomized, controlled study published in
April 2004 in Optometry showed that lutein alone, or in
combination with other antioxidants, improved visual function
in people with AMD.
What other dietary components can reduce risk?
The other thing recommended is eating extra omega-3 fatty
acids, or taking omega-3 supplements. The richest source of
omega-3 fatty acids is flaxseed oil. It's also in fish oil
so, if people prefer, they can take cod liver oil. This
recommendation is based on another Harvard study that showed
that people who consumed more omega-3 fatty acids had less
macular degeneration. People who consumed a lot of omega-6
fatty acids, however, regardless of how much omega-3 they
ingested, still had a lot of macular degeneration. The reason
is that in our bodies, omega-6s compete with omega-3s for the
same receptors. Omega-6s are in vegetable oils that are used
in all processed and packaged foods. So we recommend our
patients to take extra omega-3 fatty acids and to eat as few
packaged and processed foods as they can.
Why are dietary supplements a good option for people with
AMD?
There has been very little that has really been proven to
make a difference with AMD, but dietary supplements are in
that group that does make a difference. In the face of a
condition that is stealing your central vision, those are
pretty awesome stakes. So it makes sense to do it.
It also is psychologically beneficial to do something about
AMD. If you're told, "Well, sorry, we don't exactly know what
causes this condition and we can't really stop it from
progressing," that's a pretty big load to carry. If you can
say, "There are some things you can do that may reduce your
risk and here they are," at least (Be'eizer Hashem)
you can be a little bit proactive about it.
2005 Dr. Reuven Bruner. All Rights Reserved.
Contact him at: POB 1903, Jerusalem, 91314, Israel; Tel: (02)
652-7684; Mobile: 052 2865-821; Fax: (02) 652-7227; Email:
dr_bruner@hotmail.com
