fish oils

What Is It?
Health Benefits
Dosage Information
Guidelines for Use
General Interaction
Possible Side Effects
Evidence Based Rating Scale

What Is It?

Heralded for its heart-healthy actions, fish oils offer high concentrations of polyunsaturated fats called omega-3-fatty acids. Omega-3 fatty acids cannot be synthesized by the body. Therefore it is very important to ensure that you consume adequate sources either from diet or supplementation. While all fish contain these fats, cold-water fish--salmon, sea bass, tuna, trout, mackerel--are particularly rich sources because of their diet: plankton packed with omega-3s. Interestingly, the colder the water, the more omega-3s in the plankton. Cold-water fish also boast the most potent forms of omega-3s: the essential fatty acids known as eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA). Consumed as part of a fish-filled diet or in supplement form, omega-3s have myriad healing powers.

Scientists are constantly discovering new health benefits of fish oils and their essential fatty acids (EFAs, including omega-3s). In addition to their more notable properties as heart-healing substances, there's evidence that these fatty acids ease menstrual cramps and the pain and heavy bleeding of endometriosis. Omega-3s may even aid mental disorders such as attention hyper deficit disorder (ADHD), dyslexia, autism, and schizophrenia. Preliminary findings in people with manic depression (bipolar disorder) link fish oil supplementation to fewer mood swings and irritability. Some experts even contend that the rising tide of depression in the United States can be traced to the increasingly fish-poor diet people tend to follow.

Specifically, fish oils may help to:

·  Prevent and treat cardiovascular disease, including complications of high blood pressure. Several years ago scientists discovered why Greenland Eskimos suffer little heart disease despite their high-fat diets: They eat a lot of cold water fish. Closer examination revealed that it was the omega-3s in the fish that were protecting the hearts of these far-north inhabitants. Subsequent research revealed that the omega-3s discourage platelets in the blood from clumping together, reducing the risk that blood will clot and cause a heart attack. The omega-3s also ease strain on the heart and reduce the risk for angina (chest pain) by, among other things, reducing high blood pressure, keeping arteries flexible (they control inflammation within artery walls), lowering LDL ("bad") cholesterol and triglycerides (blood fats), and possibly even raising HDL ("good") cholesterol. Now there's evidence that omega-3s can prevent heart-rhythm abnormalities (arrhythmias) (1,2,3). In a large, recently published Lancet study, fish oil supplements (1 gram a day) significantly reduced the incidence of arrhythmias in heart attack survivors. There were many fewer deaths (and deaths from heart problems specifically) as a result (4).

·  Combat depression and other psychiatric disorders. The omega-3 fatty acids in fish oil are vital to the structure and function of the brain. Depressed persons demonstrate lower levels of eicosapentanoic acid (EPA) and docosahexaenoic acid (DHA) which may be linked to alteration in mood (5). Supplementation with fish oils may help to regulate these important chemicals. This may be especially important for women. In a study of 2,698 women and 2, 721 men women who characterized themselves as rare fish eaters were found to be nearly 3 times as likely to suffer from depression as their more frequently fish consuming counterparts (6). Women suffering from postpartum depression may also want to add fish oil to their diets, as many antidepressant drugs are passed through breast-milk (7).

·  Prevent certain cancers. Anticancer actions have been identified in omega-3s, with some recent studies reporting that even small amounts of fish (as part of the diet) can reduce the risk for colon, breast, prostate, and other cancers (8,9,10). Supplementing your diet with fish oil may also help prevent weight loss associated with cancer, and the other negative side effects that accompany conventional cancer treatments (11,12,13).

·  Treat rheumatoid arthritis. Joint stiffness and swelling caused by this painful condition may lessen because of the inflammation-fighting actions of omega-3s. Some sufferers find that they can even get by with lower doses of conventional medications (14). In one recent study, participants taking fish oil supplements daily for 12 weeks or more noticed that they were experiencing less morning stiffness and had fewer tender joints (15). Improvements increased even more after 18 to 24 weeks of taking fish oil supplements, with the benefit lingering for up to 8 weeks after the supplements were stopped.

·  Control diabetes. Nerve problems and heart disease are complications of this chronic condition. Fish oils may help by preventing nerve damage and possibly raising HDL ("good") cholesterol. On a basic, cellular level they may also improve the body's metabolic use of its own insulin while preventing coronary heart disease (16).

·  Ease symptoms of lupus, psoriasis and eczema. In people with lupus, omega-3s appear to control inflammation in the joints, skin, kidneys, and other body tissues (17). Those suffering from psoriasis or eczema may find that the irritated, itchy patches common to these ailments respond to treatment with fish oils after about a month. Interestingly, research indicates that psoriasis sufferers tend to have low levels of omega-3s.

·  Minimize Crohn's disease symptoms. This often painful bowel condition tends to flare up and then subside in cycles over time. When taken long term for preventive purposes, the essential fatty acids in fish oils will keep inflammation in the digestive tract under control. In a recent Italian study, fish oil supplements (about 3 grams in enteric-coated form a day) significantly reduced the number of flare-ups in Crohn's disease sufferers (18). All of the study participants were initially in remission but had signs of inflammation. By the end of the study, nearly 70% of the participants given a placebo had a relapse while only about 30% of those taking the fish oils capsules did.

·  Delay the onset of Raynaud's disease symptoms. Omega-3s inhibit inflammation within vessels, making fish oils potentially useful in stalling the numbness, tingling, and other symptoms resulting from exposure to cold air. One placebo-controlled study of 32 Raynaud's sufferers found that fish oil supplements slowed the appearance of such bothersome symptoms by an average of 15 minutes (often enough time to allow sufferers to avoid painful symptoms by getting to a warm place).

·  Improve air flow for asthmatics.  The high levels of omega-3s in fish oil may help alleviate the inflammation of the airways suffered by asthmatics (19). Some studies show improved forced expiratory volume (FEV) when asthmatics increased their intake of omega-3s (20). More research is necessary to determine if supplementation with omega-3s are helpful to asthmatics across the board (21).

·  Slow mental decline in dementia and Alzheimer’s disease. The omega-3 fatty acids found in fish oils contribute to brain and central nervous system health in many ways. In animal models the docosahexaenoic acid (DHA) found in fish oil may specifically help to protect the brain from the accumulation of beta amyloid plaques which accompany mental decline in Alzheimer’s (22). In human studies, using omega-3s as a part of an integrative treatment program slowed cognitive decline for 24 months (23).

·  Promote healthy development in children. The fatty acids found in fish oil facilitate the speedy growth and development of the ever changing child’s brain. Nearly 15% of brain development takes place during infancy. Ensuring that nursing mothers and infants receive appropriate amounts of omega-3s is vital to child development (24). Preliminary data shows that omega-3 supplementation may also benefit children who chronically wet the bed by inhibiting prostaglandin and renal nitric oxide production (25).

Note: Fish oils have also been found to be useful for a number of other disorders. For information on these additional ailments, see our Dosage Recommendations Chart for Fish Oils.

  • softgel
  • capsule
  • liquid

Dosage Information

Special tips:

--To prevent side effects such as belching and flatulence, avoid taking the entire dose at one time. Try splitting a 3,000 mg daily dose into three 1,000 mg doses, and take throughout the day with meals.

--Side effects vary depending on the brand, so if you have trouble tolerating one fish oil supplement, try switching to another brand.

--Don't buy cod liver oil as a source of omega-3s; the high amounts of vitamins A and D contained in these supplements can be toxic.

--There is much debate about mercury levels in fish and fish oil supplements. Buy supplements from a reputable establishment, and look for sources from the cold Nordic seas. Pollution and contamination are not as high in those waters as in U.S. sources.

--Women of childbearing age should try and consume 1 to 2 low mercury fish meals per week, so as to ensure proper omega-3 levels are passed on to their children.

--Not all fish meals are equally beneficial. Broiled or baked fish has been shown to confer more heath benefits than fried fish or fish sandwiches.

·  For preventing heart disease and related complications, lupus, psoriasis, eczema and Raynaud's disease: Take 3,000 mg fish oils a day.

·  For rheumatoid arthritis: Take 6,000 mg fish oils a day.

·  For Crohn's disease: Take 5,000 mg fish oils a day.

Be sure to check out our Dosage Recommendations Chart for Fish Oils, which lists therapeutic dosages for specific ailments at a glance.

·  The best way to get fish oils--and omega-3s--is by packing your weekly diet with fish. Aim to put such delicacies as salmon, halibut, and cod on the table three or more times a week.


·  The strongest evidence for the heart-healthy powers of the omega-3s comes from studies in which participants actually ate cold water fish regularly. Consider supplements for heart-related conditions only if you eat fish less than twice a week.


·  Inflammatory conditions such as rheumatoid arthritis require fish oils in supplement form. The reason for this is that considerably high doses of omega-3s--more than what you'd get by eating three or more servings of fish a week--are needed to decrease inflammation.


·  Take fish oil supplements with meals.


·  Fish oil supplements can rapidly go rancid; store the pills in the refrigerator and avoid buying them in bulk.

General Interaction

·  Omega-3s may intensify the blood-thinning effect of anticoagulants (blood thinners), including aspirin when taken long term. Internal bleeding--and excessive bleeding--is a risk.

Note: For information on interactions with specific generic drugs, see our WholeHealthMD Drug/Nutrient Interactions Chart.

Possible Side Effects

·  Belching, flatulence, nausea, diarrhea, and bloating may occur. Sometimes these reactions develop as a result of poor quality in the supplement manufacturing--try switching brands if you suspect this is the cause. In other cases the body has problems processing oils in general due to poor bile acid production or other intestinal problems; try reducing the dose dramatically (to about 180 mg a day) and slowly increasing it over time.

·  High doses impair the body's ability to form blood clots, raising concerns that the supplements could cause internal bleeding. However, no such reaction was detected in a study of heart disease sufferers who took 8,000 mg of fish oil supplements in addition to aspirin (an anticoagulant).

·  Very high doses of fish oils may cause your body to emit a slightly fishy odor.


·  Anyone with high triglycerides, a potentially serious situation, should get their cholesterol levels checked regularly. Fish oil is a helpful adjunct to conventional care for high cholesterol. T should not replace conventional drug treatment.

·  If you have diabetes, don't take fish oil supplements unless your doctor recommends it; some studies indicate that they may make it more difficult to control blood sugar levels.

·  Because omega-3s inhibit blood clotting, avoid taking fish oil supplements two weeks before and one week after surgery. Consult a doctor before taking the supplements if you have a chronic blood disorder.


  1. Biscione F, Totteri A, De Vita A, Lo Bianco F, Altamura G. Effect of omega-3 fatty acids on the prevention of atrial arrhythmias. Ital Heart J Suppl. 2005 Jan;6(1):53-9.
  2. Ismail HM. The role of omega-3 fatty acids in cardiac protection: an overview. Front Biosci. 2005 May 1;10:1079-88.
  3. Holub DJ, Holub BJ. Omega-3 fatty acids from fish oils and cardiovascular disease. Mol Cell Biochem. 2004 Aug;263(1-2):217-25.
  4. Thies F, Garry JM, Yaqoob P, Rerkasem K, Williams J, Shearman CP, Gallagher PJ, Calder PC, Grimble RF. Association of n-3 polyunsaturated fatty acids with stability of atherosclerotic plaques: a randomized controlled trial. Lancert. 2003; 361(9356):477-85.
  5. Ohara K. Omega-3 fatty acids in mood disorders. Seishin Shinkeigaku Zasshi. 2005;107(2):118-26.
  6. Timonen M, Horrobin D, Jokelainen J, Laitinen J, Herva A, Rasanen P. Fish consumption and depression: the Northern Finland 1966 birth cohort study. J Affect Disord. 2004 Nov 1;82(3):447-52.
  7. Rees AM, Austin MP, Parker G. Role of omega-3 fatty acids as a treatment for depression in the perinatal period. Aust N Z J Psychiatry. 2005 Apr;39(4):274-80.
  8. Kojima M, Wakai K, Tokudome S, Suzuki K, Tamakoshi K, Watanabe Y, Kawado M, Hashimoto S, Hayakawa N, Ozasa K, Toyoshima H, Suzuki S, Ito Y, Tamakoshi A; JACC Study Group. Serum levels of polyunsaturated fatty acids and risk of colorectal cancer: a prospective study. Am J Epidemiol. 2005 Mar 1;161(5):462-71.
  9. Comhaire F, Mahmoud A. Preventing diseases of the prostate in the elderly using hormones and nutriceuticals. Aging Male. 2004 Jun;7(2):155-69.
  10. Shahidi F, Miraliakbari H. Omega-3 (n-3) fatty acids in health and disease: Part 1--cardiovascular disease and cancer. J Med Food. 2004 Winter;7(4):387-401.
  11. Hardman WE. (n-3) fatty acids and cancer therapy. J Nutr. 2004 Dec;134(12 Suppl):3427S-3430S.
  12. Wynter MP, Russell ST, Tisdale MJ. Effect of n-3 fatty acids on the antitumour effects of cytotoxic drugs. In Vivo. 2004 Sep-Oct;18(5):543-7.
  13. Ramos EJ, Middleton FA, Laviano A, Sato T, Romanova I, Das UN, Chen C, Qi Y, Meguid MM. Effects of omega-3 fatty acid supplementation on tumor-bearing rats. J Am Coll Surg. 2004 Nov;199(5):716-23.
  14. Oh R. Practical applications of fish oil (Omega-3 fatty acids) in primary care. J Am Board Fam Pract. 2005 Jan-Feb;18(1):28-36.
  15. Berbert AA, Kondo CR, Almendra CL, Matsuo T, Dichi I. Supplementation of fish oil and olive oil in patients with rheumatoid arthritis. Nutrition. 2005 Feb;21(2):131-6.
  16. Nettleton JA, Katz R. n-3 long-chain polyunsaturated fatty acids in type 2 diabetes: a review. J Am Diet Assoc. 2005 Mar;105(3):428-40.
  17. Mori TA, Beilin LJ. Omega-3 fatty acids and inflammation. Curr Atheroscler Rep. 2004 Nov;6(6):461-7.
  18. Belluzzi A. N-3 fatty acids for the treatment of inflammatory bowel disease. Proc Nutr Soc. 2000. 61(3):391-5.
  19. Mickleborough TD, Ionescu AA, Rundell KW. Omega-3 Fatty acids and airway hyperresponsiveness in asthma. J Altern Complement Med. 2004 Dec;10(6):1067-75.
  20. Date Published: 04/18/2005
    Previous  |  Next
    > Printer-friendly Version Return to Top