The health of the body is often reflected in the eyes.
Circulatory problems, which are hidden elsewhere
in the body, can manifest visibly in these organs.
Similarly, the antioxidant status of the aging body
often will have a profound effect upon the eyes.
Age-related macular degeneration (AMD, a deterioration in
the retina at the point at which images are focused) is a typical
result of the aging process, as the formation of cataracts
(opaque defects in the transparency of the lens of the eye).
Prevent Blindness America estimates that AMD may affect 13
million individuals in this country. Cataracts impair the vision
of roughly four million Americans. Some authorities estimate
that thirty percent of all adults aged 70 and older suffer from
some form of vision impairment.
Diet, through its effects upon antioxidant status, may
play a significant role in these age-related degenerations.
Indeed, the eyes are especially prone to certain types of
oxidative damage. In one study of 40 to 70 year olds, for
instance, those who consumed fewer than 3.5 servings
of fruits and vegetables per day had five times the risk
for developing one type of cataract and 13 times the risk
for developing another type of cataract when compared
to those who ate more than 3.5 servings of fruits and
vegetables daily.1 Hence, a prudent plan would be to use diet
and supplements to insure the intake of a comprehensive
combination of nutrients which support the various aspects
of visual functioning and which help to maintain optimal
ocular antioxidant status.
LUTEIN AND ZEAXANTHIN, EYE SAVERS?
Lutein and zeaxanthin are important antioxidants used by
the body for a number of physiological functions. Of all the
currently recommended nutrients for the eyes, these have
perhaps received the widest general endorsement. They
are found in a variety of foods and now are also available in
significant amounts in supplemental form.
Lutein is a carotenoid, which does not supply vitamin A
activity to the body. It is chemically distinctive in that it lacks
part of the terminal “ring” structure of the other carotenoids.
Like its close relative zeaxanthin, lutein is what is termed a
xanthophyll carotenoid. Both of these related carotenoids are
better antioxidants than is beta-carotene under normal oxygen
conditions. Lutein is the more important of the two. According
to Optometry (the Journal of the American Optometric
Association), “Lutein can be metabolized into zeaxanthin and is
therefore the more essential carotenoid.” Zeaxanthin has been
shown to be present in the center of the macula. Lutein and
zeaxanthin are usually found together in leafy green vegetables,
such as kale, broccoli, spinach and mustard greens.
One of the primary functions of lutein and zeaxanthin is to
provide protection against oxidative and free radical damage.
These yellow-colored carotenoids are found in high concentrations
within the macula lutea (the yellow spot in the center of the retina)
and in smaller amounts throughout the retina and the eye lens.
They are also concentrated in the skin, breast and cervical tissues.
These stores, however, appear to diminish at an increasing rate
with age if not regularly replenished through dietary means.
FOOD SOURCES OF LUTEIN
Vegetable (1/2 cup serving)
Lutein Content (mg)
Source: Journal of the American Dietetic Association 1993:284-95
LUTEIN/ZEAXANTHIN AND THE AMD CONNECTION
Age-related macular degeneration (AMD) is the leading cause
of irreversible blindness in people over age 65. The exact
cause of AMD is not yet known, although the protective role
of nutrition against the condition is being researched at major
universities and other institutions. A study published in the
Journal of the American Medical Association concluded that a
daily intake of six mg per day of lutein led to a 43 percent lower
risk of developing AMD.2
Scientists believe that lutein and zeaxanthin contribute
to the density of macular pigment3—the component of the
retina of the eye which typically absorbs and filters out 40 to
60 percent of damaging near-ultraviolet blue light (near-UV blue
light) which strikes the retina. The denser the pigment, the more
the inner retina is protected from light-induced damage. Lutein/
zeaxanthin also helps limit blue light damage to the inner retina
by inhibiting lipid peroxidation and by neutralizing free radicals.
LUTEIN/ZEAXANTHIN AND HEALTH OF THE EYE LENS
Considerable evidence shows the importance of lutein and
zeaxanthin in reducing changes in the opacity of the eye lens as
we age. A study published in the British Medical Journal examined
cataract formation among 50,000 women over an eight-year
period.4 The results clearly showed that the consumption of
spinach, which is an excellent source of lutein and zeaxanthin,
led to a much lower level of such eye lens changes than did
the consumption of other vegetables, such as carrots, sweet
potatoes and winter squash, which contain primarily betacarotene
and very little lutein. Similarly, according to a study
published in the Journal of the American Medical Association,
people who eat foods rich in lutein—particularly kale and
spinach—are less likely to develop macular degeneration.5
The intake of carotenoids other than beta-carotene, that
is, alpha-carotene, lutein and lycopene, has been inversely
correlated with the risk of developing cataracts. In other words,
the more alpha-carotene, lutein and lycopene consumed, the
lower the incidence of cataracts.6 Protection most likely comes
from the scavenging of free radicals. Oxidative/free radical
damage to the eye lens is believed to play an important part
in the development of cataracts. Lutein/zeaxanthin prevent
peroxidation in the lens, thus limiting damage to the opacity
of this tissue. However, there is no evidence that lutein/
zeaxanthin can help to reverse an existing cataract.
BILBERRY: FOOD FOR THE EYES
Another food that has an especially strong affinity for the
eyes is bilberry. The bilberry (Vaccinium myrtillus) is a close
relative of American blueberry. It grows in Northern Europe,
Canada, and in parts of the Northern United States, where
the berries are known as huckleberries. There are over 100
species with similar names and fruit. The English call bilberries
whortleberries. The Scots know them as blaeberries.
The bilberry has many historical or traditional uses based
upon both the dried berries and the leaves. It has been used
as a medicinal herb since the 16th century. Modern interest in
the bilberry is partly based on the fruit’s use by British pilots
during the Second World War. These pilots noticed that their
night vision improved when they ate bilberry jam prior to night
bombing raids. In the intervening years, scientists discovered
that anthocyanosides, the bioflavonoid complex in bilberries,
are potent antioxidants.7 Many of the traditionally suggested
uses of bilberry, such as against scurvy and urinary tract
complaints, no doubt reflect the antioxidant, vitamin C-sparing
and anti-inflammatory properties of the berry. However, the
astringent qualities of the dried bilberry fruit and of bilberry
tea also may provide some benefits and help to explain the use
of these in folk medicine to soothe the gastrointestinal tract.8
In Europe, bilberry extracts are accepted conventionally as a
normal part of health care for the eyes.
Much of the modern research on bilberry extract has
focused upon the benefits to the eyes. Bilberry anthcyanosides
provide three primary benefits to these organs. First, these
highly colored plant pigments nourish the retina. Night vision
depends upon the retina’s ability to constantly regenerate
visual purple (rhodopsin), and anthocyanosides serve as
“building blocks” for this important substance. Tests have
confirmed these benefits. When subjects with normal vision
supplemented with bilberry extract, it was found that the
acuity of their nighttime vision improved, as did the speed at
which they adjusted to darkness and the rate at which they
recovered from blinding glare.9,10 After reviewing the literature,
some authors have suggested that bilberry extract provides
benefits even in cases of myopia.11 These findings may reflect
the importance of visual purple for visual acuity in general.
The benefits of bilberry anthcyanosides extend beyond
the regeneration of visual purple, however. The eye depends
upon a very high relative blood flow and is exposed to large
amounts of oxygen. Such factors mean that the eye is extremely
vulnerable to problems arising from capillary fragility and that
prevention of damage by free radicals plays a major role in
maintaining eye health. In Europe, bilberry extracts are widely
supplemented by individuals who are known to be subject
to eye capillary permeability and retinopathy. The expected
benefit is improved integrity of the collagen that is integral to
the support structure of the capillaries.12
Similarly, several types of deterioration, which are typical of aging eyes, such as cataracts and macular degeneration, appear
to be influenced by the rate of generation of free radicals. In
laboratory trials, changing the diets from commercial laboratory
chow to "well-defined" diets rich in flavonoids has been shown
to be beneficial.13,14 Interesting results have been found with
human trials in which bilberry extract was supplemented, either
alone or in combination with vitamin E.15,16
GRAPE SEED EXTRACT AND GINKGO BILOBA EXTRACT
Both grape seed extract and Ginkgo biloba extract enhance
the circulatory health of the eyes. Grape seed extract has been
studied very widely for it ability to reduce capillary fragility and
excessive permeability.18 It benefits to the circulatory system
are not in doubt; nor are its antioxidant benefits. Somewhat
surprising, however, are grape seed extract's benefit with regard
to recovery from glare, an important aspect of night vision. It
now appears that grape seed extract complements the benefits
in the area of night vision that are found with bilberry.
As is true of the Chinese herbal tradition, the Indian
Ayurvedic healing tradition associates Ginkgo with long life.
Modern Western research supports these beliefs from two
ancient healing traditions and has led to Ginkgo biloba extract
becoming one of the most widely used of all herbal products.19
The extract often is recommended for improving memory and
reaction time20, for improving circulation21, and for protecting
against free radical damage. Ginkgo biloba also is suggested
in traditional practices for improving the physiologic effects of
other herbs and nutrients.
SUPPORTING ANTIOXIDANT AND GLUCOSE METABOLISM
The eyes are particularly vulnerable to certain of the long-term
effects of poor blood sugar control. As is true of the nerves, the
eyes can be damaged by the products of the enzyme known as
aldose reductase. Poor control of blood sugar levels also places
the tissues of the body under oxidative stress. Blood glucose-related
vulnerabilities need to be taken into account when
considering eye health. Alpha-lipoic acid has been shown to be a
potent antioxidant for the eye in both cataract22 and glaucoma.23
It is complemented in these actions by the flavonoid quercitin,
an inhibitor of the actions of aldose reductase.
The eyes are vulnerable organs, but deterioration can be
protected against to a remarkable degree through sound
dietary practices. Dark green vegetables and fruits in shades of
blue, purple and red can be highly protective. The secret is to
consume these items daily, or at least several times per week.
A judicious use of special herbs and other supplements will
complement—not substitute for—these dietary measures.
- Jacques PF, Chylack LT Jr. Epidemiologic evidence of a role for the antioxidant vitamins and carotenoids in cataract prevention. Am J Clin Nutr. 1991 Jan;53(1 Suppl):352S-355S.
- Seddon JM, Ajani UA, Sperduto RD, Hiller R, Blair N, Burton TC, Farber MD, Gragoudas ES, Haller J, Miller DT, et al. Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. Eye Disease Case-Control Study Group. JAMA. 1994 Nov 9;272(18):1413.20.
- Johnson EJ, Hammond BR, Yeum KJ, Qin J, Wang XD, Castaneda C, Snodderly DM, Russell RM. Relation among serum and tissue concentrations of lutein and zeaxanthin and macular pigment density. Am J Clin Nutr. 2000 Jun;71(6):1555.62.
- 4 Hankinson SE, Stampfer MJ, Seddon JM, Colditz GA, Rosner B, Speizer FE, Willett WC. Nutrient intake and cataract extraction in women: a prospective study. BMJ. 1992 Aug 8;305(6849):335.9.
- Seddon JM, Ajani UA, Sperduto RD, Hiller R, Blair N, Burton TC, Farber MD, Gragoudas ES, Haller J, Miller DT, et al. Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. Eye Disease Case-Control Study Group. JAMA. 1994 Nov 9;272(18):1413. 20; Jacques PF. The potential preventive effects of vitamins for cataract and age-related macular degeneration. Int J Vitam Nutr Res. 1999 May;69(3):198.205.
- Mares-Perlman JA, Brady WE, Klein BE, Klein R, Haus GJ, Palta M, Ritter LL, Shoff SM. Diet and nuclear lens opacities. Am J Epidemiol. 1995 Feb 15;141(4):322.34.
- Salvayre R, Braquet P, et al. Comparison of the scavenger effect of bilberry anthocyanosides with various flavonoids. Proceed Int'l Bioflavonoids Symposium, Munich, 1981, 437.42.
- Grieve M. A Modern Herbal, vol. 1. (New York: Dover Publications, 1971)385.6.
- Jayle GE, Aubert L. Action des glucosides d'anthocyanes sur la vision scotopique et mesopique du sujet normal. Thereapie 1964;19:171.85.
- Caselli L. Clinical and electroretinographic study on activity of anthocyanosides. Arch Med Int1985;37:29.35.
- Mowrey D. Next Generation Herbal Medicine. (Comorant Books, 1988)15ff.
- Mian E, et al. Anthocyanosides and the walls of microvessels: Further aspects of the mechanism of action of their protective effect in syndromes due to abnormal capillary fragility. Minerva Med 1977;68:3565.81.
- Hess H, et al. Dietary prevention of cataracts in the pink-eyed RCS rat. Lab Anim Sci 1985;35:47.53.
- Pautler EL, et al. A pharmacologically potent natural product in the bovine retina. Exp Eye Res 1986;42:285.8.
- Bravetti G. Preventive medical treatment of senile cataract with vitamin E and anthocyanosides: Clinical evaluation. Ann Ottamol Clin Ocul 1989;115:109.
- Scharrer A, Ober M. Anthocyanosides in the treatment of retinopathies. Klin Monatsbl Augenheilkd 1981;178:386.9.
- Delacrois P. Double-blind study of Endotelon in chronic venous insufficiency. La Revue De Med. 1981;27:28.31.
- Boissin JP, Corbe C, Siou A. [Chorioretinal circulation and dazzling: use of procyanidolic oligomers (Endotelon)]. Bull Soc Ophtalmol Fr. 1988;88(2):173-4, 177.9. [French text]
- Castleman M. The Healing Herbs (Rodale Press, 1991).
- Schmidt U, Rabinovici K, Lande S. Enfluss eines Ginkgo biloba Specialextraktes auf doe befomdlickeit bei zerebraler Onsufficizienz. Muench Med Wochenschr 1991;133( Suppl. 1): S15-S18.
- Ernst E. Pentoxifylline for intermittent claudication. A critical review. Angiology 1994 ;45: 339.45.
- Maitra I, Serbinova E, Trischler H, Packer L. Alpha-lipoic acid prevents buthionine sulfoximine-induced cataract formation in newborn rats. Free Radic Biol Med. 1995 Apr;18:823.9.
- Filina AA, Davydova NG, Endrikhovskii SN, Shamshinova AM. [Lipoic acid as a means of metabolic therapy of open-angle glaucoma] Vestn Oftalmol 1995 Oct-Dec.;111 : 6.8.