cc >> Ann Alberts: Welcome to
today's program: Improving Diet for Eye Health
and Better Vision. We welcome you here today
and we welcome our speaker, Julie Mares.
Julie received her master's degree in public health
at Champaign University. She received her PhD in
ophthalmology and nutritional science here at the UW Madison.
We're pleased to have Julie here with us today, and let's give
her a round of applause. [APPLAUSE]
Julie Mares: Good morning. Today I'd like to share with you
highlights about food and healthy lifestyles that might
help preserve vision as we age that I've learned, doing
research in this area for about two decades, from the work that
we've done and the work that others have done.
And I will focus on work done specifically in a large
population sample, part of which took place right here in
Madison, Wisconsin. The carotenoids and age-related
eye disease study of about 2,000 women who are participants both
in the nationwide women's health initiative and also in our eye
study. Through the help of these women,
the contribution of taxpayers' money through NIH funding, and
the efforts of many people both in our research team and across
six institutions we've learned some insights that I'd like to
share with you today. I'll be telling you about many
research studies, but in particular I'll focus on these.
The tool we use in science are population studies which
involve, often, thousands of people who were kind enough to
tell us about the foods they eat, the supplements they take,
and their lifestyles. And they've also allowed us to
take photographs of their eye. We've taken photographs of the
back of their eye, or the retina, that have told us about
early and late changes that contribute to age-related
macular degeneration, a common age-related eye disease.
And they've allowed us to take photographs of their lenses to
show us about early and later stage of cataract.
Population studies, together with information from animal
studies and clinical trials, compromise a body of evidence
that help us understand whether better eating and better
lifestyles can preserve vision. In particular, population
studies tell us about the likely impact of these situations in
people over long periods of time and how people live.
I'll focus on our latest findings which include the fact
that plant pigments in our eyes might act as natural sunglasses.
I'll tell you about many of the aspects of diet that might help
preserve vision and an overall picture that represents what the
impact might be of overall healthy diets.
And I'll talk about vitamins, especially two which cost
nothing. Let's start with cataract.
Age-related cataract affects everybody.
As we age, the lens of our eye becomes more and more cloudy.
Now the lens of our eye focuses light on the back of the eye so
that we can see, and when it becomes cloudy as we age, due to
light, smoking, drugs, it causes our vision to be blurred, as you
can see on this slide. This is the most common vision
impairment in young old age, that is those of us between
65 and 75 years, and it's especially noticeable in driving
where glare becomes a problem. But it's also very common at
very late stages, late enough to have your lenses extracted by
cataract surgery. 30% of people over 65 years have
cataracts at this level, and 50% of people at age 75 either had
their cataracts extracted or have cataracts that are severe
enough to need extraction. Because it's so common, this is
a large contributor to healthcare costs, and this will
be increasingly the case as our population ages.
The last time it was estimated, cataract surgery, which is just
a simple out-patient procedure costing a couple thousand
dollars per lens, accounted for 12% of the Medicare budget.
It's estimated that we could cut these costs in half if we could
just delay the development of cataract by 10 years.
And our research is suggesting that diet is one of the most
promising ways of slowing cataract.
Cataracts can develop in different areas of the lens.
They can develop in the center of the lens, that's the most
common type for which cataract surgery is needed, or in the
lens fibers where cortical cataract develops, which is more
common in people with diabetes, or at the bottom of the capsule.
Nutrition is one of many risk factors for developing cataract.
As I mentioned, this happens with age, even as early as our
20s our lenses begin to develop opacities, and the rate of this
is more quick in some than in others.
Light exposure is known to increase the development of some
types of cataract, as is smoking, diabetes, use of some
drugs like steroids, and having certain colored eyes.
People with brown eyes are more likely to develop cataract at
early ages. It probably has nothing to do
with the fact that the eyes are brown but that this represents
people of a certain genetic background, and we're just
beginning to learn about genetic predictors of cataract.
The lens is very sensitive to abrupt changes and so in studies
in animals and people, frank nutrition deficiencies can cause
cataract and populations in which malnutrition is common
have sometimes benefited from multivitamins.
Also, it's important to realize that excess nutrients can cause
cataract as well. This has been shown in animals
and humans. Selenium, lead, possibly
Vitamin C, and high body fat contributing to cataract.
Most of what I am going to talk about today results from studies
of not frank deficiencies or excesses but where we've talked
about more moderate variations of intake where possible
protection over the moderate range has been observed in
people who've had diets that are low in refined carbohydrates and
are high in antioxidants. Vitamin C, vitamin E and were
going to focus on the carotenoid lutein as well which people have
not heard about as much as vitamin C and E.
Lutein is one of the five major carotenoids that are in the
blood. Now, carotenoids are responsible
for many of the plant pigments that you see outside in nature.
There are about 500 in nature. There's about 50 carotenoids in
the foods we eat, and only these carotenoids get absorbed in
significant quantities in our blood.
Some of these carotenoids you might recognize like beta
carotene which provides an orange color and can be
converted to vitamin A, or the red color from lycopene is in
tomatoes. Differently, lutein and
zeaxanthin are yellow pigments and it gives corn the yellow
pigment. Now, lutein is one compound and
zeaxanthin has the same chemical structure with just a slightly
different rotation. So I'll be talking about lutein
but I always mean lutein in combination with zeaxanthin.
They usually come together with the foods we eat.
Egg yolks are yellow because of lutein and zeaxanthin and their
in highest concentration in dark, leafy greens, but we don't
see it because there's also a lot of chlorophyll in these.
But you do see it if you boil leafy greens.
The yellow in the water comes from lutein and zeaxanthin.
Population studies that we have done and others have done have
found consistently lower risk for cataracts or cataracts
extraction in people who high levels of lutein in their diet.
That's one of the most consistent relationships that
I've observed in population studies.
This is true in our studies, the carotenoids and age-related eye
disease study on the right and in many other studies.
And in many studies the reduced risk is quite marked, between
one and a half to twofold. But because many aspects of
nutrition could slow the development of cataracts, we
have scored people on diets which reflect overall high
levels of many protective vitamins, minerals, and plant
pigments. We did this by computing scores
based on adherence to the US dietary guidelines, which you
can go online and look up. These are people who have higher
scores, have higher intakes of plant foods, from grains, from
fruits and vegetables. They have adequate levels of
protein in their diet from beans, eggs, meat, and dairy and
generally have lower levels of fat if their scores are higher.
We found that people who score above average levels in the
United States have about one and a half to twofold lower risk for
cataract. So it doesn't take much to
observe the lower risk. And an identical result was
found in a separate population of women, suggesting that eating
overall healthy diets can have a pretty profound impact on the
development of opacities. In our particular study, we
observed that healthy diets may be the strongest risk factor
that we can modify to slow the development of cataract.
There are some things we can't do anything about, the color of
our eyes. If we have blue or green eyes,
we're less likely to have cataract.
If we have low pulse pressure which represents having flexible
arteries, we are less likely to have cataracts.
But overall healthy diets are among the strongest thing that
we can modify to slow the development of cataract along
with avoiding gross obesity, not smoking, and having diets that
are high in individual nutrients like lutein or vitamin C.
Now let's turn our attention to age-related macular
degeneration. This is a condition which we can
also observe in the early stage from the photographs that women
allow us to take. And early signs of age-related
macular degeneration are common, present in about 25% of people
over 65 years of age. And in some, they go on to
develop advanced macular degeneration which is only
present in 5% of us over 65 but steeply increases with age so
that those of us who reach 80, about 12% of us will have
macular degeneration which severely limits vision.
It destroys the cones in the central field of vision so that
we often can't see the center of the field of vision, we often
can't see people's faces, and this is an area of the retina
that is also used to see fine details so it's harder to read
newspapers and pill bottles, for example.
And so we'll be talking about diet which not only slows the
development of the late but also slows the development of early
stages of macular degeneration which might ultimately reduce
the number of people who develop advanced stages.
What are the overall risk factors for developing this?
Well, there are some that we can't do anything about and
there are some we can modify. Family history is the strongest
risk factor for macular degeneration.
It runs in families. And in the last five years there
have been identified specific gene variants that are
associated with exaggerated response to inflammation that
might be responsible in part. Diet is one of many modifiable
risk factors for developing macular degeneration.
Smoking is consistently found in many studies to be related to
higher levels of macular degeneration, but stopping
smoking can reduce this level of risk.
In some studies, people who have a history of hypertension,
cardiovascular disease, or diabetes are more likely to
develop macular degeneration. We think that exposure to
sunlight is a strong risk factor, but our population
studies like we do don't typically see that and I think
it's because it's very hard to quantify the sun exposure that
we each get because it can be modified by such things as just
turning away from the sun and things like that.
But there is strong literature that suggests that blue light is
especially damaging to the back of the eye or the retina.
People with high body fatness are more likely to have macular
degeneration. And more recently new data that
I'll share with you suggests that people with low physical
activity and poor vitamin D status are more likely to have
macular degeneration. In terms of diet there have been
many studies that suggest a wide variety of aspects of diet that
may modify risks for macular degeneration including diets
that are high in fat and refined carbohydrates or low in omega-3
fats or fish oils or low in fish, low in these carotenoids,
lutein or zeaxanthin, in zinc or in B vitamins.
Let's focus on those carotenoids, lutein and
zeaxanthin. I've talked about the fact that
they are many of the carotenoids found in nature.
And I've talked about the fact that they are in our lens.
And in our lens we think that they reduce the accumulation of
free radicals. They're like antioxidants.
But they are especially concentrated in the back of the
eye, in the retina, and you can see that yellow patch there.
That's right in the area where macular degeneration develops.
And there we know that lutein and zeaxanthin can absorb blue
light. They can absorb 70% to 90% of
the blue light that hits the back of our eye.
So we think that that is the large part of the protection
possible of these carotenoids. They can also act as
antioxidants like vitamin C and E and quench free radicals that
are pretty common in that area due to light exposure and other
things. More recently, exciting
information in the last couple years suggest that these can
just help us see better. Increasing our macular pigment
has been shown to aid sight under conditions of glare in
college students and to quicken recovery of vision after bright
lights and to increase the ability to see contrast, which
might be especially important in low light.
Now these experiments, as I mentioned, were conducted in
college students. We don't understand the
practical significance of how much they help us see better.
But hunters have, for a long time, worn yellow blue-blocking
glasses which helps them to see far in the distance.
In fact, you can go into Walgreens and they sell hunters
glasses, blue-blockers, put them on when you go and see how
different it is to look across the room with them on and with
them off. You can get an idea how that
yellow patch might work in your eye.
See if it makes things see better.
I've heard that some people that are starting to get macular
degeneration say that it helps them to have blue-blockers on.
So they might simply help us see better but they might slow the
development of macular degeneration because of their
ability to absorb blue light. I've told you that people whose
diets are high in lutein and zeaxanthin have fewer cataracts,
and also there's a similar consistent body of literature
that suggests that people whose diets are high in these pigments
also are less likely to have advanced macular degeneration.
Our study suggests that they also have fewer signs of early
macular degeneration but the data aren't consistent and so
more studies are needed to know whether we can slow the
development at the very earliest stages.
So how do we get macular pigment?
Is it simply by taking a lutein supplement or eating more in our
diet? Well, we've done some research
to understand this better. The levels across people vary
widely. And in the study of about 2,000
women, we measured the macular pigment.
It can be done simply and noninvasively using a machine
like you see here. And I should note that machines
like this are now in some optometrist's office, although
the reliability of the individual machines is still
kind of variable in terms of what is out there.
We've used this machine and how it works is the people look into
the box and blue light is flickered together which that
pigments absorbs together with another light which our pigment
doesn't absorb. And so simply by turning the
knob until the flicker stops, we have an estimation of the amount
of yellow pigment in the back of the eye.
It's relatively simple. Using this machine, we have
found that women whose diets are high in fruits and vegetables
have more macular pigment, as you'd expect, but it's not all
due to the lutein and zeaxanthin.
Even after adjusting for lutein intake, high levels of fruits
and vegetables are related to more macular pigment.
We think that it's the other antioxidants in fruits and
vegetables that might spare the turn over of lutein.
Other researchers have found certain aspects of cooking or
certain foods might enhance absorption.
We know that carotenoids are more absorbable when they're
cooked or when they're chopped or pureed.
Also adding fat can help. There's been such a focus on
reducing fat in our diet but a little is helpful to get these
fat soluble pigments in. Also, eating eggs is a
particularly easy way to get lutein and zeaxanthin.
It is a bio-available source that is, even though eggs have a
small amount relative to leafy greens, it gets into the blood
and into the retina more readily than a similar quantity in leafy
greens. Now, supplements are out there
and they can enhance macular pigment, but they don't in all
people and we're trying to understand why, why two people
given the same amount of supplement will have different
levels get into their eye and some people not at all.
But they're out there. Some people are using them.
If you do use them, I would suggest limiting to the amount
we would normally consume in foods, about 10 milligrams,
because we don't really know the effects over long periods of
time of consuming very high doses.
We've also noticed in these experiments that people who have
diabetes or a large amount of abdominal fat where these
pigments also accumulate have lower levels of pigment in their
retina at all levels of dietary intake.
So it might be that we need more if we have diabetes or higher
levels of abdominal fat. We think these probably
represent some genetic factors that influence the lipids in our
blood, and we're currently studying these so we'll have
more answers in about a year to understand why it is that some
of us accumulate it and some of us don't.
Some people are avoiding leafy greens and there's no need to.
If you like leafy greens, these are a wonderful source of lutein
and zeaxanthin and also other vitamins and minerals and
beneficial plant compounds. If people are on blood thinners
their doctors may have advised them to avoid them because large
amounts of vitamin K in leafy greens interfere with the action
of blood thinners. But avoiding them isn't
necessary, eating a consistent level is.
So if you like leafy greens, you want to eat more of these
nutritional power houses, work with your doctor to adjust the
blood thinners to the amount of leafy greens that you want to
regularly consume. Also, if you've had kidney
stones you might have been told to avoid kale and spinach
because they have oxalates. But newer research suggests that
this isn't an important contributor to kidney stones.
Quite the opposite. Having a large amount of animal
foods, milk, meat, etc, in our diet, cheese especially, and a
low amount of plant foods contributes to more acidic blood
which tends to pull calcium from our bones which can then deposit
in places like the kidney. If you want to avoid kidney
stones, what you can do is eat diets high in plant foods over
animal foods, as well as drink plenty.
It's not necessary to avoid the leafy greens.
As with cataract, we've looked at how overall scores on healthy
diets are related to risk for macular degeneration.
We score people's diets on the current US dietary guidelines.
But also, which I've already described, but also on scores
that reflected adherence to a Mediterranean diet pattern.
This is a pattern that which was eaten by people on the island of
Crete who had long lives and low rates of heart disease in the
'50s and '60s when it was studied.
This dietary pattern is even richer in plant foods than what
is recommended by the US dietary guidelines.
It doesn't focus so much on fat amount but on fat type, giving
higher scores for the intake of monounsaturated fats such as
olive oil or walnuts and lower scores for high intake of
saturated fats in meat and in high fat dairy.
It also includes points for moderate wine consumption and
points for intake of fish which has been associated with lower
risk for macular degeneration in many studies.
So we gave women scores based on these two diet patterns, and we
observed that healthy diet patterns lowered early
age-related macular degeneration odds by quite a large amount,
two to threefold. Scoring on adherence to the US
diet guidelines, people with the lowest 20% of levels, 18% of
those women had early signs of macular degeneration, compared
to only about 10% of women who scored high on that diet
pattern. Women who had high scores on the
Mediterranean type diet pattern, the more plant rich diet type,
had even lower odds for having macular degeneration.
Only 6% of them had early signs of macular degeneration.
However, in these women from Wisconsin, Iowa, and Oregon,
only 55 women had diets that scored that well.
And so we will be repeating these types of studies across
the world in women who consume Mediterranean diet patterns to
understand whether this result sticks.
Let's turn to vitamins but we'll first talk about two that cost
nothing, vitamin D and vitamin O.
Vitamin D, you all know, is the sunshine vitamin because we can
make it in our skin on exposure to sunlight.
And it's not just for bones. We know that vitamin D helps
improve bone health, but more recently it's been understood
that it helps lower inflammation in the body and it helps lower
the development of abnormal blood vessels, both things that
contribute to macular degeneration.
Two studies that we've conducted, one in a
representative sample of the American population and another
in this carotenoids and age-related eye disease study,
have found that women who had high levels of vitamin D in the
blood had lower odds for having early macular degeneration and
it was, again, a large impact, about twofold, even after
adjusting for other things that I've told you about.
Importantly, beyond a certain level, higher blood levels of
vitamin D didn't have higher impact.
So it may not be necessary to have boatloads of vitamin D.
Also, we found some evidence that vitamin D may work together
with other aspects of diet. For example, the protective
relationship of vitamin D was stronger in people who also had
diets that were high in lutein which is just an example of how
these things work together. So how to get vitamin D.
Well, obviously from sunlight. In the summer months usually 15
to 30 minutes a day is adequate to provide good blood levels of
vitamin D. As we age or if we have darker
skin we may need a little more time.
But now we're coming on October and this is a time when the
angle of the sun is low and so our skin does not get a lot of
ultraviolet light. So if we live in the northern
latitudes, that is north of Washington, DC, or LA, we don't
make a lot of vitamin D from the sun between about October and
April, and we need to get it instead from foods.
Natural sources are few. They include fish from cold
water, egg yolks, and some mushrooms.
But many foods are fortified with vitamin D, as I'm sure your
aware, including milk, some cereals, some orange juices now,
and increasingly soy milks and yogurts.
People who don't get adequate levels from foods can supplement
and generally people recommend between 600 and 2,000 IUs.
This is an area of considerable debate right now.
Let's talk about vitamin O. I'm sure you never heard about
it because I made it up, but it represents physical activity
because of the oxygen it delivers to our tissues which
also nourish our tissues and nourish our eyes.
We found that physical activity is associated with lower odds
for macular degeneration and two other studies have found this
recently as well. In the study that we did we
estimated that risk could be cut in half by daily activity of
about an hour and a half of light activity, such as
housework or gardening, and an hour of moderate activity, like
brisk walking. And recall that if the activity
is outside we're also getting vitamin D at the same time.
How much impact could be made if we put all these healthy
lifestyles together? Diet, physical activity,
not smoking. We studied this in our sample as
well, and here you see the percent of women who had early
signs of macular degeneration stratified by people who had the
highest levels of healthy lifestyles and the lowest
levels. Women who had the highest
levels, only 6% of women who had the highest levels of physical
activity, low smoking, and high diet, had macular degeneration,
compared to 18% who had the lowest healthy lifestyle score.
So that's a threefold difference in risk associated with things
that we can do something about. Some people wonder if the impact
of diet and lifestyle could be stronger if we're genetically
prone to develop macular degeneration.
We don't know, but we're currently funded to get some
answers to this question so hopefully we'll have more
answers in the near future. So we worry about passing along
our genes to our children, to our grandchildren, if we have
macular degeneration, but we might also consider the other
things that we can pass along which are healthy lifestyles.
We know that hypertension, for example, in our early midlife
can be influenced by diet in our adolescent years.
And it's likely that the vision changes we're talking about
begin fairly early in life. So we can also pass along the
love of gardening, the good taste of a piece of fruit from
the garden or from our local market that's fresh and in
season, or walks outside in nature and pass along the
healthy lifestyles that might help protect them as well.
We've talked about food and vision in terms of just the
mechanics of the eye. But it's not just about eyes.
We're starting to learn that our ability to see also involves the
brain. This might be especially
important for people who have cataracts, macular degeneration,
diabetic retinopathy because our brain allows us to compensate
for some of the lack of vision caused by these other areas.
We don't know a lot about this. We do know that more physically
active people, people with better diets are less likely to
have cognitive deficits so we expect that the act to see
involving both the eyes and the brain might be even more when
you consider brain impact. Savoring good food and physical
activity. It's not really only about
physical health. I hesitate to focus on specific
foods that are harmful or beneficial, causing us to
struggle at every mealtime about eating unhealthy foods.
I think the research over the past 50 years causes us to fear
foods. Worrying about eating eggs and
fat and things that might not be good for us instead of enjoy the
meals that we're eating. So for some of us this means
increasing time spent going to find vitamin supplements in drug
stores and less time enjoying good food.
But it seems to me that savoring good food is just as important
and especially more important as we get older.
And the sensory input that we get from vision and hearing is
reduced. This is a way to enjoy our
senses enjoying good food. So I encourage you not to worry
too much about this. It's kind of the larger impact
of our diet, not the impact of a few foods that we might happen
to like that are not thought by some people to be healthy for
us. Similarly, with physical
activity there's much more than an opportunity to get vitamins D
and vitamin O. As Aldo Leopold once said, a
walk in nature never fails to deliver more than I expect.
May be you've found the same. Supplements certainly abound.
You'll see many of them in Walgreens.
And specifically for eye health. Let's consider if they might
help some people. If you have macular
degeneration, some US doctors do suggest taking a supplement that
was shown to reduce the risk of progressing to a more advanced
stage in the age-related eye disease study.
Often it's known by the AREDS supplement label.
This is a supplement that had very high doses of beta
carotene, a carotenoid which, by the way, does not get into the
eye, vitamin C, vitamin E, and zinc.
So some supplements that are out there in the market now have
added lutein with zeaxanthin, which does get into the eye,
fish oils, selenium, and some have lower levels of vitamin E
and zinc which might be safer. This is currently being tested
in a new age-related eye disease study trial.
It's important to avoid excess if you're taking supplements.
If you smoke, don't take beta carotene, high levels of beta
carotene are associated with an increased risk for lung cancer.
Multivitamins are probably okay. No more than the amount of
nutrients in foods, and they might have the added benefit of
providing some vitamin D. They might be especially
important if you're going through a period where your diet
is particularly compromised or people for whom food intake is
compromised over a long time. But do be aware that vitamins
and minerals can really add up if you consider the vitamins you
get not only from one supplement but many of them, the fact that
foods are fortified with nutrients, cereals are fortified
with nutrients, energy bars, and so it's probably a good idea to
share the vitamins you're taking with the nurses or dieticians or
doctor that you're working with to make sure you're not getting
too much. Because too much might not be
good and we know this is the case for many nutrients.
Vitamin C, zinc, beta carotene, vitamin A, folate, selenium, and
vitamin C. And do consider that what we
have in supplements are really current best guesses.
If these AREDS supplements could slow the development of macular
degeneration, just imagine what foods, which provide a more wide
array of vitamins and minerals and beneficial plant compounds
might do. Probably a lot as our data is
suggesting. We don't know yet if different
doses or combinations would work better.
Whether they benefit some people more than others, that's being
studied. And I often get ask should
family members at risk take supplements such as these high
dose AREDS supplements? The benefit is unknown.
We don't know yet whether it would help people.
Certainly, multivitamins would provide vitamin D which might be
helpful. But in people who are young,
these high dose supplements might provide risks that we
still don't understand, taking them over many decades.
But certainly the research that we've discussed today supports
the idea that healthy foods and exercise may be a way of slowing
the development of macular degeneration.
I often get asked about herbals. People say bilberry, wolfberry,
and astaxanthin might improve eye health.
Folk traditions suggest they will and they might, we just
haven't done systematic research.
But getting these in the store in pill form is not a certain
way of getting a level that's a good consistent level.
The safety is largely untested. And these substances or other
substances can be found in foods such as the compounds that we
think are helpful. Bilberry can be found in
blueberries, and goji berries thought to improve vision,
they're high in zeaxanthin. You can get that in leafy greens
or a particular high source would be red peppers.
Astaxanthins, been thought to be protective.
That provides the pink color in salmon.
Again, you can get that by eating fish.
What about cataracts? The evidence suggest
multivitamins might help, especially in people who are
likely to have deficient diets. High doses don't.
A recent Swedish study suggested consuming one gram of vitamin C
a day increased the risk for cataract.
So we've talked about ways to preserve eye health through
foods and healthy lifestyles, and I hope this encourages you
to enjoy real food, all types, mostly plants, move and enjoy
the outdoors, and to pass it on. Thanks.
[APPLAUSE]