Fish Oil Supplements (Omega-3 Fatty Acids EPA and DHA)

What is fish oil?

This article is about fish body oil and not fish liver oil.

Fish oil can be found in fatty fish, such as anchovies, halibut, herring, mackerel, menhaden, mussels, oysters, salmon, sardines, seal blubber, trout and whale blubber [1,25,26,27,28,29,34]. Fish oil extracted from fatty fish is available as a dietary supplement in the form of capsules or liquids.

Fish oil contains high amounts of nonessential omega-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Synonyms and related terms: fish body oil, fish extract, halibut oil, mackerel oil, marine oil, menhaden oil, salmon oil, seal oil

Other oils that also contain omega-3 fatty acids EPA and DHA: cod liver oil, krill oil

Fish Oil Composition

3 oz (85 g) of fatty fish contains 0.8-1.8 g of EPA + DHA (herring, meckerel, salmon and sardines contain most) [30,31,34].

One fish oil softgel (1 g) usually contains 0.6-1 g of EPA + DHA and various (small) amounts of saturated fat, cholesterol, vitamins A and D, and 9 Calories [32,33].

Benefits

Fish oil is EFFECTIVE in [3]:

  • Lowering high triglyceride levels, especially when taken along with cholesterol-lowering drugs statins [3,22]. It is not clear if lowering triglycerides by fish oil protects against coronary heart disease or not.

There is CONFLICTING EVIDENCE about the effectiveness of fish oil in:

  • Decreasing the risk of coronary heart disease (CHD) in individuals who have low blood levels of EPA and DHA and those with high triglyceride levels but less likely in individuals without known risk factors for CHD (when consumed as fatty fish, but not as fish oil supplements) [3,5,7,8,10,11,24,38,46,47]
  • Decreasing risk of heart attack in individuals who already had heart attack [3,24]

NOTE: Fish oil supplements may not provide any additional health benefit in individuals who regularly consume fatty fish [7].

There is INSUFFICIENT EVIDENCE about the effectiveness of fish oil in the prevention or treatment of [3] abnormal heart rhythm, acute respiratory distress syndrome (ARDS), age-related macular degeneration, aggression, antisocial personally disorder, anxiety, bacterial infections, bipolar disorder, cancer [45,46], chemotherapy side effects, chest pain, chronic obstructive pulmonary disease (COPD, bronchitis), clogged arteries, common cold, cystic fibrosis, dementia, depression [18], diabetes mellitus type 2, eczema, epilepsy, fatigue, fibromyalgia, gallstones, glaucoma, gout, hearing loss, high blood pressure (hypertension) [19,20,21], HIV/AIDS, ichthyosis, inflammatory bowel disease (Crohn’s disease [13], ulcerative colitis [15]) or other inflammation, kidney conditions (IgA nephropathy, nephrotic syndrome, stones), leprosy, liver disease, malaria, migraine, morning stiffness in rheumatoid arthritis [4,5,6], multiple sclerosis, nerve pain, osteoarthritis, osteoporosis, panic disorder, pancreatitis, Parkinson’s disease, peripheral artery disease, psoriasis, Raynaud’s disease, retinitis pigmentosa [17], schizophrenia, Sjögren’s syndrome (dry eyes and mouth), stomach disorders, stroke, systemic lupus erythematosus, transplant rejection or vasculitis, or in improving appetite, athletic performance, cognition or immune functions, longevity, memory, sun protection, surgical recovery, vision, weight loss, wound healing or as an antioxidant or blood thinner (anticoagulant).

Fish Oil for Men

There is INSUFFICIENT EVIDENCE about the effectiveness of fish oil in prevention or treatment of infertility [3] or prostate cancer [23]. There is some concern that fish oil supplements may actually increase the risk of prostate cancer [39].

Fish Oil for Women

There is INSUFFICIENT EVIDENCE about the effectiveness of fish oil in prevention or treatment of breast pain, decreased risk of allergies in children (when taken by women during pregnancy) [16], premenstrual syndrome (PMS) [3] or in improvement of pregnancy and labor or fertility [3].

Fish Oil for Children

There is probably no good reason for healthy children to take fish oil supplements. Infants should get supplements only under doctor’s supervision.

There is INSUFFICIENT EVIDENCE about the effectiveness of fish oil in prevention or treatment of asthma [14] or attention deficit hyperactivity disorder (ADHD) [3], autism [3], dyslexia [3], phenylketonuria [3] or sickle cell disease [3] or in infant developing [3].

Children should avoid fish high in mercury, such as shark, swordfish tuna and tilefish.

Dosing

Commonly used doses of fish oil for adults for different purposes are 0.6-20 grams per day for few months to few years [40]. Discuss with your doctor before taking any fish oil supplements.

Examples of doses by mouth [40]:

  • To lower high blood triglycerides: 2-15 g/day for up to 3 years
  • To lower high blood pressure: 2-4 g/day up to 1 year
  • To treat coronary heart disease: 10 g/day for 12 weeks
  • To prevent coronary artery narrowing after angioplasty: 15 x 1 g capsule/day for 3 weeks

Examples of doses for intravenous infusion:

  • To treat rheumatoid arthritis: 0.2 g/kg [40]

Safety

Fish oil supplements are LIKELY SAFE when used in recommended doses for up to 2-3.5 years [9]. Up to 20 grams of fish oil supplements per day may be tolerated by most adults [9].

Pregnancy and Breastfeeding

Fish oil, when taken in recommended doses, is POSSIBLY SAFE during pregnancy and breastfeeding [9]. The U.S. Environmental Protection Agency (EPA) recommends that pregnant and breastfeeding women limit sport-caught fish intake to 6 ounces per week and avoid other fish that can be high in mercury, such as king mackerel, shark, swordfish and tilefish and to limit other fish to 12 ounces per week [9].

Fish oil is pregnancy category C, which means that not enough studies have been done to establish if it is safe for the unborn babies or not [36].

Who should avoid fish oil supplements?

Do not take fish oil if you are allergic to fish.

Children, pregnant and breastfeeding women, anyone with diabetes, hypothyroidism, liver or pancreatic disorder, drinking excessive amounts of alcohol (more than 2 drinks per day) or taking contraceptive pills, blood thinners, beta-blockers, diuretics or other drugs should speak with a doctor before taking omega-3 supplements [36].

Side Effects

Fish oil supplements may cause one or more of the following side effects:

  • Fishy body odor
  • Indigestion
  • Increased risk of bleeding, when taken in doses >3 grams/day
  • Irregular heart rhythm (arrhythmia)
  • A mild raise of blood LDL cholesterol levels
  • Raise of blood sugar levels (hyperglycemia)
  • A slight drop of blood pressure
  • Allergic reaction with skin itch, hives, facial swelling, cough, dizziness, difficulty breathing, headache and weakness
  • References: [9,36,37]
Fish Oil Supplements Omega 3

Fish Oil Supplements Omega 3

Other possible side effects or risks of fish oils supplements [9,37]: acid reflux, anemia, anorexia, asthma, bad breath, bad taste in the mouth, bloating, blood in urine, blurred vision, bronchitis, burping, cataract, colon cancer, common cold, constipation, lowered immunity, depression, diarrhea, excess fat in the stool, excessive urination, excessive gas, excessive sweating, fever, impotence, mania, memory problems, muscle, joint, back, chest or neck pain, nausea, nosebleed, prostate cancer [39], sleep problems, tingling (paresthesia), vertigo, vitamin E deficiency, vomiting and weight gain.

Toxicity – How much fish oil is too much?

Fish oil is Generally Recognized As Safe (GRAS) according to the U.S. Food and Drug Administration (FDA) [35].

There is an increased risk of bleeding with doses greater than 3 grams per day [9].

There is a small risk of mercury poisoning by consumption of large amount of fatty fish such as shark, swordfish, king mackerel, tilefish (golden bass or golden snapper), farmed salmon and albacore tuna [2,9]. Fish oil supplements do not likely contain dangerous amounts of mercury [9,44]. Some fatty fish, such as herring, farmed salmon, sardines, trout and tuna can also contain high amounts of polychlorinated biphenyls (PCBs).

There is little chance that fish body oil supplements taken regularly, long-term and in large amounts may cause vitamin A or D toxicity [9].

NOTE: Fish liver oils, such as cod liver oil (but not fish body oils) may contain more than 180,000 IU/g of vitamin A. The acute toxic dose of vitamin A is 25,000 IU/kg (10 fish-liver oil capsules taken by a 70 kg or 154 lbs individual), and the chronic toxic dose is 4,000 IU/kg (1.5 fish liver oil capsules by a 70 kg or 154 lbs individual ) every day for 6-15 months [43].

Fish Oil Interactions with Drugs

Fish oils supplements taken along with blood thinners, such as aspirin, clopidogrel, heparin or warfarin, or supplements, such as Ginkgo biloba, garlic and saw palmetto, may increase the risk of bleeding [9].

References
  1. Fish oil WebMD
  2. Omega-3 fatty acids, fish oil, alpha-linolenic acid, background Mayo Clinic
  3. Omega-3 fatty acids, fish oil, alpha-linolenic acid, evidence Mayo Clinic
  4. Miles EA et al, 2012, Influence of marine n-3 polyunsaturated fatty acids on immune function and a systematic review of their effects on clinical outcomes in rheumatoid arthritis PubMed
  5. Rheumatoid arthritis: in depth National Center for Complementary and Integrative Health
  6. Plendzki BC et al, 2011, Treatment of Rheumatoid Arthritis with Marine and Botanical Oils: Influence on Serum Lipids Hindawi
  7. Mohebi-Nejad A et al, 2014, Omega-3 Supplements and Cardiovascular Diseases PubMed Central
  8. Omega-3 fatty acids, fish oil, alpha-linolenic acid, safety Mayo Clinic
  9. Walden R et al, 2011, Cardiovascular disease Herbal Medicine: Biomolecular and Clinical Aspects, 2nd edition
  10. Omega-3 supplements: in depth National Center for Complementary and Integrative Health
  11. Gupta SC et al, 2013, Therapeutic Roles of Curcumin: Lessons Learned from Clinical Trials PubMed Central
  12. Lev-Tzion C et al, 2014, Omega 3 fatty acids (fish oil) for maintenance of remission in Crohn’s disease Cochrane
  13. Thien FCK et al, 2000, Dietary marine fatty acids (fish oil) for asthma in adults and children Cochrane
  14. De Ley M et al, 2007, Fish oil for the treatment of active ulcerative colitis Cochrane
  15. Gunaratne AW et al, 2015, Fish oil (n-3 or omega-3) for pregnant mothers or breastfeeding mothers to prevent allergies in their young children Cochrane
  16. Rayapudi S et al, 2013, Use of vitamin A and fish oils for retinitis pigmentosa Cochrane
  17. the Common Mental Disorders Group, 2015, Does fish oil really make a difference to depression? Cochrane Australia
  18. Campbell F et al, 2013, A systematic review of fish-oil supplements for the prevention and treatment of hypertension PubMed
  19. Yang H et al, 2007, The role of fish oil in hypertension PubMed
  20. Geleijnse JM et al, 2002, Blood pressure response to fish oil supplementation: metaregression analysis of randomized trials PubMed
  21. Eslick GD et al, 2009, Benefits of fish oil supplementation in hyperlipidemia: a systematic review and meta-analysis PubMed
  22. Lovegrove C et al, 2015, Systematic review of prostate cancer risk and association with consumption of fish and fish-oils: analysis of 495,321 participants PubMed
  23. Kromhout D et al, 2012, Fish oil and omega-3 fatty acids in cardiovascular disease: do they really work? PubMed Central
  24. List of foods high in EPA US Department of Agriculture
  25. List of foods high in DHA US Department of Agriculture
  26. List of foods high in sodium US Department of Agriculture
  27. Mercury Levels in Commercial Fish and Shellfish (1990-2010) US Food and Drug Administration
  28. 2008, Health fish, healthy families Association of Reproductive Health Professionals
  29. List of foods high in EPA US Department of Agriculture
  30. List of foods high in DHA US Department of Agriculture
  31. Press R, 2011, The Omega-3 Fatty Acid Composition and Cost Analysis of Fish Oil Supplements: Fishing for the Best Deals, A senior honors thesis The Knowledge Bank at The Ohio State University
  32. Fish oil, cod liver US Department of Agriculture
  33. Fish oil Drugs.com
  34. Fish oil, side effects Drugs.com
  35. Rizos EC et al, 2012, Association between omega-3 fatty acid supplementation and risk of major cardiovascular disease events: a systematic review and meta-analysis PubMed
  36. Brasky TM et al, 2013, Plasma phospholipid fatty acids and prostate cancer risk in the SELECT trial PubMed
  37. Omega-3 fatty acids, fish oil, alpha-linolenic acid, dosing Mayo Clinic
  38. 2008, Healthy fish, healthy families Association of Reproductive Health Professionals
  39. Grubb BP et al, 1990, Hypervitaminosis A following long-term use of high-dose fish oil supplements PubMed
  40. Rosenbloom M, Vitamin toxicity, overview Emedicine
  41. Smutma M et al, 2009, Fish oil and cod liver as safe and healthy food supplements PubMed
  42. MacLean CH et al, 2006, Effects of omega-3 fatty acids on cancer risk: a systematic review PubMed
  43. Hooper L et al, 2006, Risks and benefits of omega 3 fats for mortality, cardiovascular disease, and cancer: systematic review PubMed
  44. Bucher HC et al, 2002, N-3 polyunsaturated fatty acids in coronary heart disease: a meta-analysis of randomized controlled trials PubMed
  45. Image Copyright 123rf.com : Manachai Phongruchiraphan

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