Study shows that omega-3s exert a protective effect against a common ocular affliction
by Craig Weatherby
A recently published review of the medical literature gives an old show biz saying new meaning. Instead of signifying an emotionally affecting drama, the phrase “not a dry eye in the house” now applies to many who enjoy oily fish on a frequent basis.
Past research showed that omega-3s in fish and fish oil reduce the risk of both cataracts and age-related macular degeneration (AMD) modestly, and help prevent the more common condition known as dry eye syndrome (DES).
Dr. J. James Thimons, O.D.—a leading lecturer on eye disease—published a new literature review this year in the journal Optometric Management. His research (see “Omega-3s versus dry eye”, below) confirms that omega-3s benefit the eyes in many ways, including alleviation and prevention of DES.
When eyes go dry
Dry eye syndrome affects more women than men, with an estimated 3.2 million American women middle-aged and older—including many in their 40s and 50s—suffering symptoms.
In fact, DES is one of the most common problems eye doctors see in clinical practice today, occurring in up to 25 percent of all patients. The dryness of this ubiquitous condition—also known as ocular surface disease—causes pain, burning sensations, itchiness, and, in some cases, excess tearing.
The two most common forms are the aqueous-deficient type of DES in which there’s not enough production of the watery layer, and the evaporative type, in which there’s not enough of the lipid (outer, fatty) layer to keep tears from evaporating.
Omega-3s versus dry eye syndrome: a clinical view
Dr. J. James Thimons authored a literature review article in the July, 2005 issue of Optometric Management, which described the evidence in favor of using supplemental marine omega-3s—and the plant derived omega-6 fatty acid called GLA—for dry eye syndrome. He also pointed out a key safety advantage over standard drug therapy:
- “Numerous studies have demonstrated the efficacy of omega-3 essential fatty acids in the treatment of dry eye disease... work with mass spectroscopy showed that omega-3 fatty acids are the basic building blocks of healthy meibomian oils [The meibomian glands in the eyelids make an oily lubricant called sebum]. The Women's Health Study, which included 34,000 subjects, showed a direct correlation between dietary levels of omega-3 fatty acids and dry eye symptoms.”
- “The majority of clinical experience with the omega-3s is based on the use of a 2,000 mg dose. This can be taken all at one time or split-up through the day… omega-3 fatty acid therapy typically takes months to demonstrate significant improvement. While this presents a challenge in some instances, a recently published study showed an increased risk of breast cancers with chronic doxycycline therapy. [Editor's note: This is the standard drug therapy.] This should create sufficient concern to make omega-3 fatty acids the primary choice in all patients without contraindications (platelet abnormalities, anticoagulant therapy and high dose aspirin therapy).
- “Omega-3 fatty acid therapy has become standard in the treatment of dry eye, [and] gives the clinician an excellent, natural therapy that can be used indefinitely to help the patient maintain a normal, healthy ocular surface and general overall health.
Women’s Health Study offers hope for tears from fish
Researchers led by Dr. Jeffrey Gilbard, an eye specialist at Harvard Medical School in Boston, studied more than 32,000 female health-care professionals and found that those with the highest intake of omega-3 fats had a 17 per cent lower risk of developing dry eye syndrome (DES) compared with those who ate the least.
The study, presented in 2003 at the annual meeting of the Association for Research in Vision and Ophthalmology (Trivedi KA, et al), showed that women who ate five or six servings of tuna per week had a 66 per cent lower risk of developing dry eye syndrome than women who ate fewer than two servings per week.
As the authors concluded, “These results suggest that women with a higher dietary intake of omega-3 fatty acids are at decreased risk of developing DES. Although this is the first study that has evaluated this relationship, and confirmation from other studies is needed, the findings are consistent with clinical observations and postulated biological mechanisms.”
Why eyes go dry
In most cases the immediate cause of DES is chronic inflammation in the “tear film” of the eye, triggered by air conditioning, air pollution, allergies, certain medications, thyroid conditions, pre-/peri- and postmenopause, systemic autoimmune diseases like Sjogren's, lupus, and rheumatoid arthritis, contact lenses, laser eye surgery and spending prolonged periods staring at computer screens.
Omega-3s probably help because they are anti-inflammatory. A pro-inflammatory cytokine (messenger protein) called Interleukin I is more prevalent in the tear film and thin, transparent outer tissue (conjunctiva) of dry eye patients than in normal eyes. Cytokine-mediated inflammation in the surface of the eye is associated with the inflammatory conditions that often underlie dry eye.
It seems we should all strive to acquire “fish eyes”.
- Trivedi KA, Dana MR, Gilbard JP, Buring JE, Schaumberg DA. Dietary Omega-3 Fatty Acid Intake and Risk of Clinically Diagnosed Dry Eye Syndrome in Women. Program#/Poster#: 811/B786. Association for Research in Vision and Ophthalmology annual meeting, May 4-9 2003, Fort Lauderdale, FL.
- Schaumberg DA, Sullivan DA, Buring JE, Dana MR. Prevalence of dry eye syndrome among US women. Am J Ophthalmol. 2003 Aug;136(2):318-26.
- Barabino S, Rolando M, Camicione P, Ravera G, Zanardi S, Giuffrida S, Calabria G. Systemic linoleic and gamma-linolenic acid therapy in dry eye syndrome with an inflammatory component. Cornea. 2003 Mar;22(2):97-101.
- Cermak JM, Papas AS, Sullivan RM, Dana MR, Sullivan DA. Nutrient intake in women with primary and secondary Sjogren's syndrome. Eur J Clin Nutr. 2003 Feb;57(2):328-34.
- Thimons JJ. Nutrition and Dry Eye: A Natural Relationship. Optometric Management, Jul 2005
- Cho E, Hung S, Willett WC, Spiegelman D, Rimm EB, Seddon JM, Colditz GA, Hankinson SE. Prospective study of dietary fat and the risk of age-related macular degeneration. Am J Clin Nutr. 2001 Feb;73(2):209-18.
- Lu M, Cho E, Taylor A, Hankinson SE, Willett WC, Jacques PF. Prospective study of dietary fat and risk of cataract extraction among US women. Am J Epidemiol. 2005 May 15;161(10):948-59.
- Rand Evidence Report 114, commissioned by US Health Department. Effects of omega-3 fatty acids on cognitive function with aging, dementia and neurological diseases. AHRQ No. 05- E011-2, 2005
- SanGiovanni JP and Chew EY. The role of omega-3 long-chain polyunsaturated fatty acids in health and disease of the retina. Prog in Retinal Eye Res 24:87-138, 2005.