For many years, the logical treatment for dry eyes has
been to attempt to supplement the tear film with additional lubrication. The
science of lubrication has come a long way and now we realize that it is more
than just adding moisture to resolve this problem. New methods of
treatment have included enhanced artificial tears, punctum plugs, lipid layer
enhancements, tear quality enhancements and epithelial surface treatments.
In the past few years a new approach to resolving this
condition has included using oral supplementation. This article will look at
the facts and fiction surrounding the oral treatment of dry eye syndrome.
EFA: Good fats for eye health
Essential fatty acids (EFAs) are involved with producing
life energy in our bodies from food substances and moving that energy
throughout our systems. They hook up oxygen, electron transport and energy in
the process of oxidation. EFAs are also important in oxygen transfer,
hemoglobin production and control of nutrients through cell membranes. They are
also key in preventing damage from hard fats because they are
anti-sticky and tend to disperse them.
EFAs play a part in almost every function of our body.
Humans do not produce fatty acids; therefore they must be obtained from the
diet. Two essential fatty acids are omega-6 and omega-3.
Omega-6 plentiful in diet
Omega-6 fatty acids are the most plentiful in our diet.
They are in almost everything we eat that contains fat, including meat, most
seed oil, dairy products and eggs. Omega-3 fatty acids are available in many
seed oils and nearly all cold-water fatty fish.
A proper balance of these fatty acids is essential to
good health. The daily intake recommendation of the Institute of Medicine is
4:1 four times as many omega-6 fatty acids as omega-3 fatty acids. It is
currently estimated that the average American diet maintains a ratio of up to
Fatty acids are stored in every cell membrane of our
body. They have two primary functions: First, they ensure cellular fluidity,
acting as sentinel gatekeepers for every cell, allowing vital nutrients to
enter the cell and forcing destructive free radical debris out of the cells.
Second, both omega-6 and omega-3 fatty acids can be converted into three
different types of active molecules called prostaglandins. These
prostaglandins, PGE1, PGE2 and PGE 3, are site specific.
Omega-6 reduces inflammation
It is suggested that omega-6 fatty acids metabolize to
the site-specific anti-inflammatory ecosinoid, prostaglandin E1 (PGE1), which
is believed to reduce ocular surface inflammation and the inflammatory process
associated with meibomianitis and reduced lacrimal gland aqueous output.
The typical American diet is overloaded with omega-6
linoleic acid (LA) from vegetable oils such as sunflower, safflower, corn and
soybean oils, which are added to nearly all processed foods. Many pantries are
far too full of overly processed crackers, chips, cookies and cakes and the
omega-6 oils that oxidize too quickly and become pro-inflammatories.
However, good health also depends on omega-6 gamma
linolenic acid (GLA), which is a downstream metabolite of LA and is found in
sources such a black currant seed oil, borage oil and evening primrose oil.
This compound is a necessary component in the downstream metabolism of omega-6
fatty acid to PGE1, which is associated with healthy mucosal tissue and healthy
tear film. The human body cannot metabolize omega-3 fatty acids to these
specific anti-inflammatory prostaglandins.
Most omega-6 fatty acids are consumed in polyunsaturated
vegetable oils as LA. Excessive intake of LA is unhealthy, because it can
promote inflammation if it is not properly metabolized. In contrast, omega-6
fatty acids that are successfully metabolized or those that have the metabolic
advantage of containing GLA reduce inflammation after further metabolizing to
dihomo-gamma-linolenic acid (DGLA), which also blocks, when appropriate, the
pro-inflammatory arachidonic acid conversion.
Omega-6 needs omega-3
Successful DGLA downstream metabolism of omega-6 to the
anti-inflammatory PGE1 is secured by omega-3 EPA (preferably, fish oil)
blockage of arachidonic acid if those particular omega-3 metabolites are
present in the body. This could possibly explain the benefits attributed to
omega-3 fatty acids.
Good health depends on omega-6 gamma linolenic acid, a downstream metabolite of linoleic acid. This compound is a necessary component in the downstream metabolism of omega-6 fatty acid to PGE1, which is associated with healthy mucosal tissue and healthy tear film.
Image: Troyer E
Both omega-3 and omega-6 EFAs are
short-chain acids and must metabolize to long-chain molecules to be
effective in the body. However, this conversion is not guaranteed, and this is
especially true for omega-3, where it is estimated that only 2% to 15% of the
ingested material metabolizes completely to long-chain EFAs.
The body requires all of the essential fatty acids for
optimal health. They are particularly important for the patient with dry eye,
because PGE1s from omega-6 interrupt the inflammatory loop associated with
chronic dry eye syndrome. The PGE1s also increase the anti-inflammatory
immunomodulating effects of cyclosporine.
Oral supplement needs omega-6, GLA
A good nutritional supplement should address many of the
underlying inflammatory processes associated with dry eye syndrome. Oral
administration of specific omega-6 essential fatty acids that contain
sufficient amounts of GLA are suggested to stimulate the natural production of
Black currant seed oil is an excellent source of omega-6
GLA because it is more stable than either borage oil or evening primrose oil.
Many anecdotal stories abound regarding the use of flax seed oil. However, it
is the most unstable of the essential fatty acid oils, and it does not contain
GLA. Flax stability issues keep it from easily converting to GLA, which is
something it must do to produce PGE1.
In looking for a tear-specific formula for oral
administration, be sure to look for nutrient cofactors necessary to address dry
eye syndrome by physiologic rather than pharmacological means. These
ingredients are designed to work synergistically rather than individually, and
effectively address the inflammatory process responsible for most dry eye
syndrome, as well as enhancing and restoring function to the glands involved in
all three layers of the tear film.
Treating idiopathic dysfunctional tear film with oral
nutritional supplements can be an effective method to resolve this frustrating
and uncomfortable condition. While it is worthwhile to uncover the cause of the
condition, using the right combination of ingredients can work regardless of
the causative factors.
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