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|| ISSN(online): 2589-8698 || ISSN(print): 2589-868X ||
International Journal of Medical and Biomedical Studies
Available Online at www.ijmbs.info
PubMed (National Library of Medicine ID: 101738825)
Index Copernicus Value 2018: 75.71
Review Article Volume 4, Issue 3; March: 2020; Page No. 194-198
194 | P a g e
ROLE OF NUTRITION IN MAINTAINING NORMAL EYESIGHT-A REVIEW
Naghma Nazrana1, Dr. Tejasvi Jain2, Dr. Sanjay Verma3
1Lecturer, JVW, University, Jaipur
2Assistant Lecturer, JVW, University, Jaipur
3Assistant Professor, Muzaffarnagar, Medical College
Article Info: Received 10 February 2020; Accepted 24 March 2020
DOI: https://doi.org/10.32553/ijmbs.v4i3.1068
Corresponding author: Naghma Nazrana
Conflict of interest: No conflict of interest.
Abstract
The eye is particularly susceptible to oxidative stress as a result of its high oxygen consumption, high concentration of
polyunsaturated fatty acids and cumulative exposure to high-energy visible light. This combination of factors leads to the
generation of reactive oxygen species that can trigger oxidative damage to ocular tissues. There is evidence that the human
consumer should avoid excessive supplementation with carotenoids. Poly-unsaturated fatty acids are linked to eye disease
(as well as multiple other chronic diseases) in both positive and negative ways. Dietary poly-unsaturated fatty acids fall into
two major groups, i.e., omega-6 (mainly linoleic acid and arachidonic acid) and omega-3 fatty acids, mainly alpha-linolenic
acid, eicosapentaenoicacid (EPA) and docosahexaenoic acid (DHA). Vitamin A deficiency is rare in the United States, but it is
common among the poor in developing countries. It's estimated that approximately 250,000 to 500,000 malnourished
children worldwide become blind each year due to vitamin A deficiency that could have been prevented with a proper diet.
A lack of vitamin A causes the cornea to become very dry, leading to clouding of the front of the eye, corneal ulcers and
vision loss. Vitamin A deficiency also causes damage to the retina, which also contributes to blindness.
Keywords: Vitamin A, DHA, Glaucoma, retinopathy
Introduction
Vitamin A helps protect of the eye (cornea), it is essential
for good vision Studies show vitamin A eye drops are
effective for the treatment of dry eyes. In fact, one study
found that over-the-counter lubricating eye drops
containing vitamin A were as effective for the treatment of
dry eye syndrome as more expensive prescription eye
relief.
Your risk of developing an eye disease increases as you get
older. The most common eye diseases include:
Cataracts. A condition in which lens become clouded.
Age-related cataracts are a leading cause of vision
impairment and blindness around theworld.
Diabetic retinopathy. Associated with diabetes and a
major cause of visual impairment and blindness,
retinopathy develops when high blood sugar levels
damage the blood vessels in yourretina.
Dry eye disease. A condition marked by insufficient
production of tear, which causes your eyes to dry up and
leads to discomfort and potential visualproblems.
Glaucoma. A group of diseases characterized by
progressive degeneration of optic nerve. Glaucoma may
cause poor eyesight orblindness.
Macular degeneration. The macula is the central part
of your retina. Age-related macular degeneration (AMD) is
one of the main causes of blindness in developed
countries.[1]
Globally, approximately 250 million people suffer from
varying degrees of vision loss [2]. Leading causes include
several eye conditions considered in this Special Issue,
such as cataract, AMD, glaucoma, and diabetic
retinopathy. These conditions disproportionately affect
older adults, and with an ageing population the number of
affected individuals is predicted to increase exponentially
[2]. Whilst the etiology of age-related eye disease is
complex and multifactorial, oxidative stress has been
implicated as a common causative mechanism. The eye is
particularly susceptible to oxidative stress as a result of its
high oxygen consumption, high concentration of
polyunsaturated fatty acids and cumulative exposure to
high-energy visible light. This combination of factors leads
to the generation of reactive oxygen species that can
trigger oxidative damage to ocular tissues. Consequently,
there has been significant research interest in the role of
dietary antioxidants and the potential therapeutic benefits
of antioxidant vitamin and mineral supplements as a
simple and cost-effective strategy for disease prevention
and control[3–5].
The present overview places carotenoids into the context
of [6] familiar organisms and objects colored by
carotenoids, [7] their roles in human vision, with an
emphasis on protection by zeaxanthin and lutein against
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International Journal of Medical and Biomedical Studies (IJMBS)
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vision loss, [8] synergistic interactions of zeaxanthin and
lutein with other dietary factors affect human vision, and
[9] a comparison of the photo-physics of light collection
and photoprotection in photosynthesis and vision and their
common principles that might be rewarding targets of
future research.[10]
There is evidence that the human consumer should avoid
excessive supplementation with carotenoids [11,12]. For
example, daily supplementation with excessive amounts of
β-carotene for several years actually increased the risk of
lung cancer of male. In addition, blue- green algal
(cyanobacterial) supplements (with high levels of a class of
highly oxygenated xanthophylls called ketocarotenoids)
caused crystalline ketocarotenoid deposits in the human
eye [13]. Currently available blue- green algal supplements
thus need to be viewed with caution, due to potential
adverse effects of ketocarotenoid accumulation.
Yellow food:
Eggs, yellow corn, and yellow peppers are probably the
richest dietary sources of zeaxanthin and lutein in the
United States. These food sources receive all of their
yellow-to-orange color from their zeaxanthin and lutein
content. In contrast, green leafy plant foods typically
contain high levels of lutein, but very.[14]
Just as is the case for animals, plants and algae also use
carotenoids for bothlight collection AND photoprotection
against the destructive effects of intense light. The
xanthophylls zeaxanthin and lutein stand out as primary
agents of photoprotection in plants. Zeaxanthin facilitates
the safe removal of potentially damaging excessive
excitation energy [15,16]; zeaxanthin’s close isomer lutein
plays a minor role in the same process of the dissipation of
excessive excitation [17]. In addition, zeaxanthin also
provides plant photoprotection by direct inhibition of the
oxidation of lipids of the photosynthetic membrane (lipid
peroxidation;[18,19]
Exposure to reactive oxygen (readily formed in highly
oxygenated tissues, such as the human eye) leads to
preferential peroxidation of poly-unsaturated fatty acids.
Poly-unsaturated fatty acids are linked to eye disease (as
well as multiple other chronic diseases) in both positive
and negative ways. Dietary poly-unsaturated fatty acids fall
into two major groups, i.e., omega-6 (mainly linoleic acid
and arachidonic acid) and omega-3 fatty acids, mainly
alpha-linolenicacid, eicosapentaenoicacid (EPA) and
docosahexaenoic acid (DHA). A balanced ratio of dietary
omega-6 to omega-3 fats (below 10:1 and perhaps as low
as 2:1) is needed to support humanhealth (including the
health of the human eye), while the modern western diet
provides a highly unbalanced ratio of about 10–20:1 [20].
Sweet potatoes and carrots:
Sweet potatoes and carrots are excellent sources of
provitamin A carotenoids that are good for your eyes:
Vitamin A from animal-derived foods is called retinol.
This "pre-formed" vitamin A can be used directly by the
body. Good food sources of retinol vitamin A include beef
and chicken liver, whole milk andcheese.
Vitamin A obtained from colorful fruits and vegetables
is in the form of "provitamin A" carotenoids, which are
converted to retinol by the body after the food is ingested.
Good food sources of provitamin A carotenoids include
carrots, sweet potatoes, spinach, kale and cantaloupes.
Eye Benefits of Vitamin A and Beta-Carotene
Vitamin A eye drops also have been shown effective for
the treatment of a specific type of eye inflammation
called Vitamin A, at least when in combination with other
antioxidant vitamins, also appears to play a role in
decreasing the risk of vision loss from
maculardegeneration (AMD). In the landmark Age-Related
Eye Disease Study (AREDS) sponsored by the National Eye
Institute, people with mild or moderate AMD who took a
daily multivitamin that included vitamin A (as beta-
carotene), vitamin C, vitamin E, zinc and copper had a 25
percent reduced risk of advanced AMD during a six-year
period.[21]
It also appears that a combination of vitamin A and
lutein may prolong vision in people suffering from
retinitis pigmentosa (RP). A four-year study conducted by
researchers from Harvard Medical School and other
prominent universities found that individuals with retinitis
pigmentosa who took daily supplements of vitamin A
(15,000 IU) and lutein (12 mg) had a slower loss of
peripheral vision than those who did not take the
combined supplements. Because beta-carotene is
converted into vitamin A in the body, it's likely this
provitamin A offers similar eye benefits as the pre-formed
retinol type of vitamin A, though more research is needed
to confirm this. Researchers at Columbia University
Medical Center found that a synthetic, altered form of
vitamin A might be able to slow the progression of
Stargardt's disease, an inherited eye disease that causes
severe vision loss in youngpeople.
When given to mice with the same genetic defect as
humans with Stargardt's disease (also called juvenile
macular degeneration), the modified vitamin A inhibited
the growth of clump-like deposits in the retina called
"vitamin A dimers" that are associated with degenerative
changes and vision loss. The National Eye Institute has
awarded the researchers a $1.25 million grant to further
investigate the link between vitamin A dimers and various
retinal degenerations, which could lead to new approaches
to treat these diseases.
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International Journal of Medical and Biomedical Studies (IJMBS)
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Vitamin A Deficiency
Vitamin A deficiency is rare in the United States, but it is
common among the poor in developing countries. It's
estimated that approximately 250,000 to 500,000
malnourished children worldwide become blind each year
due to vitamin A deficiency that could have been
prevented with a proper diet. One of the first signs of
vitamin A deficiency is night blindness. In ancient Egypt, it
was discovered that night blindness could be cured by
eating liver, which later was found to be a rich source of
vitamin A. A lack of vitamin A causes the cornea to become
very dry, leading to clouding of the front of the eye,
corneal ulcers and vision loss. Vitamin A deficiency also
causes damage to the retina, which also contributes to
blindness. Because vitamin A also is important for
resistance to infection and a healthy immune system,
vitamin A deficiency can lead to death from respiratory
and other infections.[22]
Vitamin A - Daily Value:
In most cases, it's best to obtain vitamins and minerals
from a healthy, balanced diet. The concept of the Daily
Value (DV) was developed to help consumers determine if
a food contains a lot or a little of a nutrient, based on its
Recommended Dietary Allowance. The DV for vitamin A is
5,000 IU.
A healthy diet for your eyes should include plenty of
colorful fruits and vegetables:
Incorporating the following foods in your diet will help you
get the Recommended Dietary Allowance (RDA) of these
important eye nutrients. Established by the Institute of
Medicine (National Academy of Sciences),[23] the RDA is
the average daily dietary intake level of a nutrient
sufficient to meet the requirements of nearly all healthy
individuals in a specific life stage and gender group.
While the RDA is a useful reference, some care
practitioners recommend higher daily intakes of certain
nutrients for people at risk for eye problems. (In the
following list, mg = milligram; mcg = microgram (1/1000 of
a mg) and IU = International Unit.)
Beta-carotene
Eye benefits of beta-carotene: When taken in
combination with zinc and vitamins C and E, beta-carotene
may reduce the progression of macular degeneration.
Food sources: Carrots, sweet potatoes, spinach, kale,
butternut squash
RDA: None (most supplements contain 5,000 to
25,000IU).
Bioflavonoids (Flavonoids)
Eye benefits of bioflavonoids: May protect against
cataracts and maculardegeneration.
Food sources: Tea, red wine, citrus fruits, bilberries,
blueberries, cherries, legumes, soyproducts
RDA: None
Lutein and Zeaxanthin
Eye benefits of lutein and zeaxanthin: May prevent
cataracts and maculardegeneration
Food sources: Spinach, kale, turnip greens, collard
greens,squash
RDA:None
Omega-3 Fatty Acids
Eye benefits of omega-3 fatty acids: May help prevent
macular degeneration (AMD) and dryeyes
Food sources: Cold-water fish such as salmon, mackerel
and herring; fish oil supplements, freshly ground
flaxseeds,walnuts
RDA: None; but for cardiovascular benefits, the
American Heart Association recommends approximately
1,000 mgdaily.
Selenium
Eye benefits of selenium: When combined with
carotenoids and vitamins C and E, may reduce risk of
advanced AMD
Food sources: Seafood (shrimp, crab, salmon, halibut),
Brazil nuts, enriched noodles, brownrice
RDA: 55 mcg for teens and adults (60 mcg for women
during pregnancy and 70 mcg whenbreast-feeding).
Vitamin A
1. Eye benefits of vitamin A: May protect against night
blindness and dryeyes
2. Food sources: Beef or chicken liver; eggs, butter, milk.
3. RDA: 3,000 IU for men; 2,333 IU for women (2,567 IU
during pregnancy and 4,333 IU whenbreast-feeding).
Vitamin C
Eye benefits of vitamin C: May reduce the risk of Food
sources: Sweet peppers (red or green), kale, strawberries,
broccoli, oranges,cantaloupe
RDA: 90 mg for men; 70 mg for women (85 mg during
pregnancy and 120 mg whenbreast-feeding).
Vitamin D
Eye benefits of vitamin D: May reduce the risk of
maculardegeneration
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International Journal of Medical and Biomedical Studies (IJMBS)
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Food sources: Salmon, sardines, mackerel, milk; orange
juice fortified with vitaminD
RDA: None, but the American Academy of Pediatrics
recommends 400 IU per day for infants, children and
adolescents, and many experts recommend higher daily
intakes foradults.
The best source of vitamin D is exposure to sunlight.
Ultraviolet radiation from the sun stimulates production of
vitamin D in human skin, and just a few minutes of
exposure to sunlight each day (without sunscreen) will
insure your body is producing adequate amounts of
vitaminD.
Vitamin E
Eye benefits of vitamin E: When combined with
carotenoids and vitamin C, may reduce the risk of
advancedAMD
Food sources: Almonds, sunflower seeds,hazelnuts.
RDA: 15 mg for teens and adults (15 mg for women
during pregnancy and 19 mg whenbreast-feeding).
Zinc
Eye benefits of zinc: Helps vitamin A reduce the risk of
night blindness; may play a role in reducing risk of
advancedAMD
Food sources: Oysters, beef, Dungeness crab, turkey
(darkmeat).
RDA: 11 mg for men; 8 mg for women (11 mg during
pregnancy and 12 mg whenbreast-feeding).
Conclusion:
In general, it's best to obtain most nutrients through a
healthy diet, including at least two servings of fish per
week and plenty of colorful fruits and vegetables. If you
plan to begin a regimen of eye vitamins, be sure to discuss
this with your optometrist or ophthalmologist. Taking too
much of certain vision supplements can cause problems,
especially if you are taking prescription medications for
health problems. It also appears that a combination of
vitamin A and lutein may prolong vision in people suffering
from retinitis pigmentosa (RP). A four-year study
conducted by researchers from Harvard MedicalSchool and
other prominent universities found that individuals with
retinitis pigmentosa who took daily supplements of
vitamin A (15,000 IU) and lutein (12 mg) had a slower loss
of peripheral vision than those who did not take the
combined supplements. Because beta-carotene is
converted into vitamin A in the body, it's likely this
provitamin A offers similar eye benefits as the pre-formed
retinol type of vitamin A, though more research is needed
to confirm this.
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