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Omega-3 fatty acids, fish oil, alpha-linolenic acid

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Also listed as: Fish oil, Docosahexaenoic acid (DHA, C22:6n-3), Eicosapentaenoic acid (EPA, C20:5n-3), n-3 fatty acids, Alpha-linolenic acid (ALA, C18:3n-3), Polyunsaturated fatty acids (PUFA)
Related terms
Background
Evidencetable
Tradition
Dosing
Safety
Interactions
Attribution
Bibliography

Related Terms
  • ALA, alpha-linolenic acid (ALA, C18:3n-3), cod liver oil, coldwater fish, DHA, docosahexaenoic acid (DHA, C22:6n-3), docosapentaenoic acid (DPA, 22:5n-3), DPA, eicosapentaenoic acid (EPA, C20:5n-3), EPA, fish body oil, fish extract, fish liver oil, fish oil fatty acids, halibut oil, long-chain polyunsaturated fatty acids, Lovaza®, mackerel oil, marine oil, MaxEPA®, menhaden oil, n-3 fatty acids, n-3 polyunsaturated fatty acids, Omacor®, omega fatty acids, omega-3 fatty acids, omega-3 oils, Omegaven®, polyunsaturated fatty acids (PUFAs), PUFA, salmon oil, seal oil, shark liver oil, w-3 fatty acids.
  • Note: Should not be confused with omega-6 fatty acids.

Background
  • Dietary sources of omega-3 fatty acids include fish oil and certain plant and nut oils. Fish oil contains both docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), while some nuts (such as English walnuts) and vegetable oils (such as canola, soybean, flaxseed, linseed, and olive oils) contain alpha-linolenic acid (ALA).
  • There is supportive evidence from multiple studies that suggests the intake of recommended amounts of DHA and EPA in the form of dietary fish or fish oil supplements lowers triglycerides; reduces the risk of death, heart attack, dangerous abnormal heart rhythms, and strokes in people with known cardiovascular disease; slows the buildup of atherosclerotic plaques ("hardening of the arteries"), and lowers blood pressure slightly. However, high doses may have harmful effects, such as an increased risk of bleeding. Although similar benefits have been proposed for alpha-linolenic acid, the scientific evidence is less compelling, and the beneficial effects may be less pronounced.
  • Some species of fish carry a higher risk of environmental contamination, such as with methylmercury.

Evidence Table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. GRADE *


Evidence suggests that people who have low levels of EPA and DHA may have an increased risk of developing acute coronary syndrome (ACS) (a type of heart disease). Clinical trials suggest that supplementation with omega-3 fatty acids has positive benefits in terms of reduced cardiovascular disease mortality and total mortality.

A


There is strong scientific evidence from human trials that omega-3 fatty acids from fish or fish oil supplements (EPA plus DHA) significantly reduce blood triglyceride levels. Benefits appear to be dose-dependent. Fish oil supplements also appear to cause small improvements in high-density lipoprotein (HDL, or "good") cholesterol. However, increases in (worsening of) low-density lipoprotein (LDL, or "bad") cholesterol levels have also been observed. It is not clear if alpha-linolenic acid significantly affects triglyceride levels, and there is conflicting evidence in this area. The American Heart Association has published recommendations for EPA plus DHA. Because of the risk of bleeding from omega-3 fatty acids, a qualified healthcare provider should be consulted prior to starting treatment with supplements.

A


Multiple human trials have reported small reductions in blood pressure with intake of omega-3 fatty acids. DHA may have greater benefits than EPA. However, high daily intakes of omega-3 fatty acids may be necessary to obtain clinically relevant effects, and at high dose levels, there is an increased risk of bleeding. Therefore, a qualified healthcare provider should be consulted prior to starting treatment with supplements.

A


Multiple randomized controlled trials have reported improvements in morning stiffness and joint tenderness with the regular intake of fish oil supplements for up to three months. Benefits have been reported as additive with anti-inflammatory medications such as NSAIDs (like ibuprofen or aspirin). Effects beyond three months of treatment have not been well evaluated.

A


Several well-conducted randomized controlled trials have reported that in people with a history of heart attack, regular consumption of oily fish or fish oil or omega-3 supplements reduces the risk of nonfatal heart attack, fatal heart attack, sudden death, and all-cause mortality (death due to any cause). Most patients in these studies were also using conventional heart drugs, suggesting that the benefits of fish oils may add to the effects of other therapies.

A


Initial clinical evidence suggests that fish oil in combination with gamma-linolenic acid decreases the severity and duration of adult respiratory distress syndrome. Further clinical research is required to confirm this finding.

C


Population evidence suggests that a diet high in omega-3 polyunsaturated fat may decrease the risk of macular degeneration. A randomized trial of the combination product Photorop, which contains a combination of acetyl-L-carnitine, omega-3 fatty acids, and coenzyme Q10, showed improvement with treatment compared to control patients. Also, the omega-3 fatty acid DHA was found to cause central increases of macular pigment optical density in nonsmoking older women. This may be promising initial evidence of benefit, but additional, well-designed clinical trials are required before a conclusion can be made.

C


Initial clinical research suggests that fish oil may reduce the development of stress-related aggression and may help regulate mood and impulse control. Additional research is required to further evaluate this effect.

C


Clinical studies of fish oil in combination with arginine or other nutritional supplementation in patients with HIV have found conflicting results on immunologic function and body composition. Additional, large-scale clinical trials are needed to further evaluate the use of fish oil in this population.

C


Population research suggests a reduced risk of child eczema associated with fish consumption of once per week or more. However, the associations between maternal fish in the diet and eczema at two years were insignificant. Maternal supplementation decreased the risk of food allergy and IgE-associated eczema in the first year. Further research is required to determine the effect of omega-3 fatty acids on other symptoms of allergy.

C


Preliminary studies have reported reductions in angina (chest pain) associated with fish oil intake. Better research is necessary before a firm conclusion can be drawn.

C


Omega-3 supplementation resulted in reduced tension in patients attending an abuse clinic. Further research is required.

C


Several studies in this area do not provide enough reliable evidence to form a clear conclusion, with some studies reporting no effects and others finding benefits. Because most studies have been small and without clear descriptions of design or results, the results cannot be considered conclusive.

C


Some research has reported that regular intake of fish or fish oil supplements reduces the risk of developing atherosclerotic plaques in the arteries of the heart, while other research has reported no effects. Additional evidence is necessary before a firm conclusion can be drawn in this area.

C


Research on the effect of fish oil in this context is limited. In wrestlers, pulmonary function was improved. Also, omega-3 fatty acids may offer benefit for delayed-onset muscle soreness. Additional research is required before a conclusion can be drawn.

C


Fish oil supplementation resulted in increases in omega-3 fatty acids in the blood in patients with attention-deficit hyperactivity disorder (ADHD), a condition associated with decreased blood omega-3 levels. Clinical research has demonstrated benefit in patients with ADHD treated with a combination product containing both omega-6 and omega-3 fatty acids. Further research is required to determine the effect of omega-3 fatty acids for learning and behavioral problems associated with ADHD.

C


Evidence is inconclusive with respect to the potential benefits of omega-3 fatty acids for autism. Further research is required.

C


Several studies in this area do not provide enough reliable evidence to form a clear conclusion.

C


Several population studies have reported that dietary omega-3 fatty acids or fish oil may reduce the risk of developing breast, colon, or prostate cancer. Additional research is needed in this area.

C


There is promising evidence that omega-3 fatty acids may decrease the risk of cardiac arrhythmias (abnormal heart rhythms). This is one proposed mechanism behind the reduced number of heart attacks in people who regularly ingest fish oil or EPA plus DHA. Additional research is needed in this area before a firm conclusion can be made.

C


Omega-3 fatty acid consumption is associated with reduced cardiovascular disease risk markers. Further research is required to determine if the actual risk of cardiovascular disease is reduced in these populations.

C


There is limited clinical evidence on the effect of fish oil in combination with other essential fatty acids in this condition. Additional research is required before a conclusion can be drawn.

C


In patients who consumed an omega-3 fatty acid-rich diet, bronchodilator need was reduced, and oxygen saturation was improved. Further research is required to confirm these results.

C


EPA plus DHA did not have an effect on cognition in healthy elderly individuals or in healthy children. Further research is required to determine the effect of omega-3 fatty acids on cognition in healthy individuals.

C


Omega-3 fatty acid supplementation in combination with arginine and nucleotides in critically ill patients has been reported to decrease the risk of serious complications and to decrease the length of hospital stay. However, results reported to date are conflicting, and additional research is needed to further quantify the benefit of fish oil supplementation in critically ill patients.

C


A small amount of research in this area does not provide enough reliable evidence to form a clear conclusion. Additional research is needed in this area.

C


Population studies suggest a link between decreased omega-3 fatty acids in the diet and increased risk of dementia. Well-designed clinical trials are needed before omega-3 fatty acids can be recommended for the prevention of cognitive impairment or dementia.

C


Several studies on the use of omega-3 fatty acids in depression, including positive results in postpartum depression, do not provide enough reliable evidence to form a clear conclusion. However, based on one recent study, omega-3 fatty acids may have therapeutic benefits in childhood depression. Promising initial evidence requires confirmation with larger, well-designed trials.

C


Hemodialysis patients were found to consume fewer omega-3 fatty acids in the diet. The relationship between omega-3 fatty acid status and mortality in hemodialysis patients has been investigated. Additional research is needed to further quantify the benefits associated with fish oil use in this population.

C


In early research, a combination of EPA and carnosine had a lack of effect on reading and spelling problems in children with dyslexia. Further research is required.

C


There is preliminary evidence suggesting possible benefits of fish oil or omega-3 fatty acids in patients with dysmenorrhea (painful menstruation). Additional research is necessary before a firm conclusion can be reached.

C


The effect of omega-3 fatty acids, along with other polyunsaturated fatty acids and vitamin E, on dyspraxia in children has been examined. Although benefits were apparent, further research is required to determine the role of omega-3 fatty acids.

C


Several studies of EPA for eczema do not provide enough reliable evidence to form a clear conclusion. Additional research is needed in this area.

C


Clinical research has demonstrated reduced oxygen consumption during exercise in fish oil-supplemented athletes. However, other studies have reported no effect of fish oil on energy efficiency or metabolism in healthy subjects. Additional research is required before a conclusion can be made.

C


In patients with epilepsy, omega-3 fatty acid supplements may improve brain energy metabolism and increase the level of phospholipids in the brain. More research is needed to determine if this is an effective treatment for patients with epilepsy.

C


In children supplemented with fish oil in chocolate milk, there were fewer episodes of illness. Further research is required.

C


Although there is strong scientific evidence from human trials that omega-3 fatty acids from fish or fish oil supplements (EPA plus DHA) significantly reduce blood triglyceride levels, fish oil may increase (worsen) low-density lipoprotein (LDL, or "bad") cholesterol levels. The American Heart Association has published recommendations for EPA plus DHA. Because of the risk of bleeding from omega-3 fatty acids, a qualified healthcare provider should be consulted prior to starting treatment with supplements.

C


There are conflicting results from several trials in this area. Additional research is needed.

C


Further research is required to determine the effect of fish oil on immune function in humans.

C


Well-designed research is necessary before a clear conclusion can be reached.

C


In infants, 20 milligrams of DHA daily for the first year had a lack of effect on several aspects of infant development but did reduce time to the first occurrence of sitting without support. Further research is required.

C


The effect of DHA- and arachidonic acid-enriched formulas has been investigated in preterm and term infants on safety, growth, and developmental outcomes. Overall, results suggest benefits in preterm infants. More research is needed to understand exactly how omega-3 fatty acids may affect the growth and development of unborn babies and infants.

C


In patients in an intensive care unit, omega-3 fatty acids did not affect inflammation or clinical outcome. Further research is required.

C


The benefit of omega-3 fatty acids in the prevention of relapse of Crohn's symptoms and in decreased inflammation associated with ulcerative colitis has been shown. However, the results are conflicting. No clear conclusion may be drawn at this time.

C


Well-designed research is necessary before a clear conclusion can be reached in this area.

C


There is not enough reliable evidence to form a clear conclusion in this area.

C


Conclusions with respect to potential benefits of omega-3 fatty acids for menopausal symptoms cannot be drawn at this time. Further research is required.

C


Well-designed research is necessary before a clear conclusion can be reached in this area.

C


Well-designed research is necessary before a clear conclusion can be reached in this area.

C


Well-designed clinical trials are needed before a conclusion can be made in this area.

C


There is not enough reliable evidence to form a clear conclusion in this area. Further research is necessary.

C


Omega-3 fatty acids may be of benefit in the management of pain. Further research is required before conclusions can be drawn.

C


Additional research is warranted to further evaluate the benefit of fish oil supplementation in this population.

C


Evidence supporting the use of fish oil for osteoarthritis is currently lacking. Well-designed research is necessary before a clear conclusion can be reached.

C


Population and clinical studies have reported a decreased risk of osteoporosis with fish intake or fish oil supplementation. Further research is necessary before a clear conclusion can be reached.

C


In pancreatitis patients, fish oil in addition to parenteral nutrition diminished the hyperinflammatory response. Further research is needed in this field.

C


Some evidence suggests that fish oil may improve blood pressure in the legs of patients with peripheral vascular disease (PVD) and improve the ability to walk long distances. There is a lack of research showing consistent improved clinical outcomes. More research is needed to further evaluate this effect.

C


Low levels of DHA are common among children with phenylketonuria (PKU) during the first year of life due to dietary restrictions. Early research suggests that long-chain polyunsaturated fatty acid (LCPUFA) supplementation of PKU diets during the first year of life improves fatty acid levels in the body so that they are similar to those of healthy, breastfed infants. More clinical research is needed to verify this effect.

C


Several studies of fish oil do not provide enough reliable evidence to form a clear conclusion in this area. Further research is necessary.

C


Preliminary evidence suggests that fish oil has no effect on the timing of spontaneous delivery. Further research is necessary before a clear conclusion can be reached.

C


There is limited study of the use of fish oils in patients after undergoing coronary artery bypass grafting (CABG). Additional evidence is necessary before a firm conclusion can be drawn in this area.

C


Several randomized controlled trials have evaluated whether omega-3 fatty acid intake reduces blockage of arteries in the heart following balloon angioplasty (percutaneous transluminal coronary angioplasty, or PTCA). The evidence in this area remains inconclusive.

C


Several studies have reported that individuals who regularly consume foods high in alpha-linolenic acid (ALA) may have a reduced risk of heart attack. Additional research is necessary before a conclusion can be drawn in this area.

C


There is limited clinical evidence regarding the use of fish oil for prostate disorders. Additional research is necessary before a conclusion can be drawn in this area.

C


Several studies in this area do not provide enough reliable evidence to form a clear conclusion. Further research is necessary.

C


Omega-3 fatty acids did not appear to improve the quality of life in an elderly population. Further research is required.

C


Initial clinical evidence suggests that omega-3 fatty acids improve cold intolerance and delay the onset of vasospasm in patients with Raynaud's phenomenon. Additional research is warranted to further evaluate this effect.

C


There is promising preliminary evidence from several studies in this area. Additional research is necessary before a firm conclusion can be reached.

C


Several studies have examined the effects of alpha-linolenic acid (ALA) in people with a history of heart attack. Although some studies suggest benefits, others do not. Additional research is necessary before a conclusion can be drawn in this area.

C


Omega-3 fatty acids may reduce mortality, antibiotic use, and length of hospital stay in different diseases, including sepsis. DHA was found to increase body fat and length in infants following sepsis, but endpoints, such as reduced mortality, were not presented. Further research is required.

C


Several large studies of populations have examined the effects of omega-3 fatty acid intake on stroke risk. Some studies suggest benefits, while others do not. Effects are likely on stroke risk, and very large intakes of omega-3 fatty acids may actually increase the risk of hemorrhagic (bleeding) stroke. At this time, it is unclear if there are benefits in people with or without a history of stroke, or if effects of fish oil are comparable to other treatment strategies.

C


Preliminary evidence suggests that using a nutritional product enriched in arginine, omega-3 fatty acids, and RNA may improve preoperative and postoperative inflammatory and immune responses. Further research is required.

C


Initial evidence of a relationship between essential fatty acid levels, schizophrenia, and movement disorders, including tardive dyskinesia (movement disorders), is inconclusive. Further research is warranted.

C


Additional research is required before a conclusion can be drawn in this area.

C


Preliminary evidence suggests potential benefits. However, additional research is required before a conclusion can be drawn.

C


Preliminary evidence in humans suggests omega-3 fatty acids do not aid in wound healing. However, evidence is lacking. Further research is required.

C


There is preliminary evidence that fish oil supplementation does not improve appetite or prevent weight loss in cancer patients. Further research is warranted.

D


The available scientific evidence suggests that there are no long-term effects of fish oil in patients with diabetes. Most studies in this area are not well-designed, and further research is necessary.

D


There are multiple studies of heart transplant and kidney transplant patients taking cyclosporine (Neoral®), who were administered fish oil supplements. The majority of trials have reported improvements in kidney function and reduced blood pressure compared to patients not taking fish oil. However, several recent studies report no benefits on kidney function, and no changes have been found in rates of rejection or graft survival. Further research is necessary.

D
* Key to grades

A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)


Tradition / Theory

The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

  • Acute myocardial infarction (heart attack), agoraphobia (a type of anxiety disorder), Alzheimer's disease, anthracycline-induced cardiac toxicity, anticoagulation (decreased blood coagulation), antioxidant, antiphospholipid syndrome, bacterial infections, borderline personality disorder, breast cysts, breast tenderness, cardiac arrest, central nervous system disorders (Zellweger syndrome), cirrhosis, common cold, congestive heart failure, deficiency (omega-3 fatty acid), dermatomyositis, diabetic neuropathy, fatigue, fibromyalgia, gallstones, gastrointestinal disorders, gingivitis, glaucoma, glomerulonephritis, gout, hay fever, hearing loss (age-related), hepatorenal syndrome, hypoxia, ichthyosis (skin disorder), infertility, kidney disease prevention, leprosy, leukemia, malaria, male infertility, mastalgia, memory enhancement, mental retardation, metabolic disorders (glycogen storage diseases), methotrexate toxicity, mortality reduction, musculoskeletal problems (cartilage destruction), myopathy, nephritis (autoimmune), neurological disorders (Refsum's syndrome), night vision enhancement, otitis media (ear infection), panic disorder, postpartum depression, protection from isotretinoin drug toxicity, psychiatric disorders (childhood), retinitis pigmentosa, Reye's syndrome, Sjögren's syndrome, substance abuse, suicide prevention, tennis elbow, vasculitis (Behcet's syndrome), vision enhancement.

Dosing

Adults (18 years and older):

  • Average Americans consume approximately 1.6 grams of omega-3 fatty acids daily, of which about 1.4 grams (~90%) comes from alpha-linolenic acid, and only 0.1-0.2 grams (~10%) comes from EPA and DHA. In Western diets, people consume roughly 10 times more omega-6 fatty acids than omega-3 fatty acids. These large amounts of omega-6 fatty acids come from the common use of vegetable oils containing linoleic acid (for example, corn oil, evening primrose oil, pumpkin oil, safflower oil, sesame oil, soybean oil, sunflower oil, walnut oil, and wheat germ oil). Because omega-6 and omega-3 fatty acids compete with each other to be converted to active metabolites in the body, benefits can be reached either by decreasing intake of omega-6 fatty acids or by increasing omega-3 fatty acids.
  • For healthy adults with no history of heart disease, the American Heart Association recommends eating fish at least two times per week. In particular, fatty fish are recommended, such as anchovies, bluefish, carp, catfish, halibut, herring, lake trout, mackerel, pompano, salmon, striped sea bass, tuna (albacore), and whitefish. It is also recommended consuming plant-derived sources of alpha-linolenic acid, such as tofu, soybeans, walnuts, flaxseed oil, and canola oil. The World Health Organization and governmental health agencies of several countries recommend consuming 0.3-0.5 grams of EPA plus DHA and 0.8-1.1 grams of alpha-linolenic acid daily. A doctor and pharmacist should be consulted for dosing for other conditions.

Children (younger than 18 years):

  • Omega-3 fatty acids are used in some infant formulas, although effective doses have not been clearly established. Ingestion of fresh fish should be limited in young children, due to the presence of potentially harmful environmental contaminants. Fish oil capsules should not be used in children except under the direction of a physician.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

  • People with a known allergy or hypersensitivity to fish should avoid fish oil or omega-3 fatty acid products derived from fish. Skin rash has been reported rarely. People with a known allergy or hypersensitivity to nuts should avoid alpha-linolenic acid or omega-3 fatty acid products that are derived from the types of nuts to which they react.

Side Effects and Warnings

  • The U.S. Food and Drug Administration (FDA) classifies intake of up to three grams of omega-3 fatty acids from fish daily as GRAS (generally regarded as safe).
  • Fish oil supplements may cause nausea, diarrhea, loose stools, decreased appetite, constipation, vomiting, and fat in the stools. Gastrointestinal side effects may be minimized if fish oils are taken with meals and if doses are started low and gradually increased.
  • Mild elevations in liver function tests (alanine aminotransferase) have been reported rarely.
  • There are rare reports of mania in patients with bipolar disorder or major depression. Restlessness and formication (the sensation of ants crawling on the skin) have also been reported.
  • Other potential side effects include loss of short-term memory, headache, hemolytic anemia (abnormal breakdown of red blood cels), depression, somatic disorders (physical symptoms associated with psychological symptoms), increased risk of colon cancer, nasopharyngitis (inflammation in nose and throat), worsening of asthma symptoms, decreased physical activity, increased appetite, increased blood pressure, and an uncomfortable feeling.
  • Fish meat may contain potentially harmful contaminants, such as dioxins, methylmercury, and polychlorinated biphenyls (PCBs). Caution is warranted in young children and pregnant or breastfeeding women.
  • Omega-3 fatty acids may increase blood sugar levels. Caution is advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Blood glucose levels may need to be monitored by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.
  • Omega-3 fatty acids may increase low-density lipoprotein (LDL, or "bad") cholesterol levels. Caution is advised in patients with high levels of LDL cholesterol.
  • Omega-3 fatty acids may worsen symptoms for patients with ventricular tachycardia (rapid heartbeat). Use cautiously in patients with ventricular tachycardia (rapid heartbeat) or ventricular arrhythmia (abnormal heart rhythm).
  • Omega-3 fatty acids may increase the risk of bleeding. Caution is advised in patients with bleeding disorders or those taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.
  • Omega-3 fatty acids may decrease blood pressure. Caution is warranted in patients with low blood pressure or in those taking blood pressure-lowering medications.
  • Fish oil taken for many months may cause a deficiency of vitamin E and may increase the risk of vitamin A or D toxicity. Use large amounts cautiously.
  • Use cautiously in individuals at risk for hormone imbalance or those undergoing hormone replacement therapy, as decreased estrogen receptor production has been associated with fish oil supplementation.
  • Use cautiously in patients with asthma, inflammatory bowel disease, or liver disease, and in patients at risk for colon cancer, based on potential adverse effects associated with fish oil use.
  • Avoid in individuals with a known hypersensitivity or allergy to fish oil or omega-3 fatty acid products derived from fish. Skin rashes have been reported rarely. Individuals with a known allergy or hypersensitivity to nuts should avoid alpha-linolenic acid or omega-3 fatty acid products that are derived from the types of nuts to which they react.

Pregnancy and Breastfeeding

  • Potentially harmful contaminants, such as dioxins, methylmercury, and polychlorinated biphenyls (PCBs), are found in some species of fish and may be harmful in pregnant or nursing women. Methylmercury accumulates in fish meat more than in fish oil, and fish oil supplements appear to contain almost no mercury. Therefore, these safety concerns apply to eating fish but likely not to ingesting fish oil supplements. However, unrefined fish oil preparations may contain pesticides.
  • It is not known if omega-3 fatty acid supplementation of women during pregnancy or breastfeeding is beneficial to infants. It has been suggested that high intake of omega-3 fatty acids during pregnancy, particularly DHA, may increase birthweight and gestational length. However, higher doses may not be advisable due to the potential risk of bleeding. Fatty acids are added to some infant formulas.
  • The U.S. Environmental Protection Agency (EPA) recommends that fish intake be limited in pregnant and nursing women to a single six-ounce meal per week, and in young children to less than two ounces per week.
  • Women who might become pregnant are advised to eat seven ounces of fish with higher levels of methylmercury or less per week, or up to 14 ounces per week of fish types with about 0.5 parts per million (such as marlin, orange roughy, red snapper, or fresh tuna).

Interactions

Interactions with Drugs

  • In theory, omega-3 fatty acids may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants (blood thinners) such as warfarin (Coumadin®) or heparin, antiplatelet drugs such as clopidogrel (Plavix®), and nonsteroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).
  • According to human studies, omega-3 fatty acids may lower blood pressure and add to the effects of drugs that may also affect blood pressure.
  • Fish oil supplements may increase blood sugar levels a small amount. Caution is advised when using medications that may also affect blood sugar. Patients taking insulin or drugs for diabetes by mouth should be monitored closely by a qualified healthcare provider. Medication adjustments may be necessary.
  • Omega-3 fatty acids lower triglyceride levels but can actually increase (worsen) low-density lipoprotein (LDL, or "bad") cholesterol levels by a small amount. Therefore, omega-3 fatty acids may add to the triglyceride-lowering effects of agents like niacin or nicotinic acid, fibrates such as gemfibrozil (Lopid®), or resins such as cholestyramine (Questran®). However, omega-3 fatty acids may work against the LDL-lowering properties of "statin" drugs like atorvastatin (Lipitor®) and simvastatin (Zocor®).
  • Fish oil or omega-3 fatty acids may also interact with agents that affect the immune system, antiarrhythmic agents, antiarthritic agents, antiasthma agents, anticancer agents, antidepressants, anti-inflammatory agents, antipsychotic agents, antiretroviral agents, dexamethasone, hepatotoxic agents, hormonal agents or antihormonal agents, and paclitaxel.

Interactions with Herbs and Dietary Supplements

  • In theory, omega-3 fatty acids may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.
  • According to human studies, omega-3 fatty acids may lower blood pressure and theoretically may add to the effects of agents that may also affect blood pressure.
  • Fish oil supplements may increase blood sugar levels a small amount. Caution is advised when using herbs or supplements that may also affect blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.
  • Omega-3 fatty acids lower triglyceride levels but can actually increase (worsen) low-density lipoprotein (LDL, or "bad") cholesterol levels by a small amount. Therefore, omega-3 fatty acids may add to the triglyceride-lowering effects of agents like niacin or nicotinic acid, but they may work against the potential LDL-lowering properties of agents like barley, garlic, guggul, psyllium, soy, or sweet almond.
  • Fish oil taken for many months may cause a deficiency of vitamin E, and therefore vitamin E is added to many commercial fish oil products. As a result, regular use of vitamin E-enriched products may lead to elevated levels of this fat-soluble vitamin. Fish liver oil contains the fat-soluble vitamins A and D, and therefore fish liver oil products (such as cod liver oil) may increase the risk of vitamin A or D toxicity. Since fat-soluble vitamins may build up in the body and cause toxicity, patients taking multiple vitamins regularly or in high doses should discuss this risk with a qualified healthcare professional.
  • Fish oil and omega-3 fatty acids may also interact with agents that affect the immune system, antiarrhythmic agents, antiarthritic agents, antiasthma agents, anticancer agents, antidepressants, anti-inflammatory agents, antioxidants, antipsychotic agents, antiretroviral agents, conjugated linolenic acid, evening primrose oil, folate, gamma-linolenic acid, glucosamine, hepatotoxic agents, hormonal agents or antihormonal agents, lycopene, medium-chain triglycerides, phosphatidylserine, phytosterols, policosanol, and selenium.

Attribution
  • This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography
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  9. Joensen, A. M., Schmidt, E. B., Dethlefsen, C., Johnsen, S. P., Tjonneland, A., Rasmussen, L. H., and Overvad, K. Dietary intake of total marine n-3 polyunsaturated fatty acids, eicosapentaenoic acid, docosahexaenoic acid and docosapentaenoic acid and the risk of acute coronary syndrome - a cohort study. Br J Nutr 2010;103(4):602-607.
  10. Koletzko, B., Uauy, R., Palou, A., Kok, F., Hornstra, G., Eilander, A., Moretti, D., Osendarp, S., Zock, P., and Innis, S. Dietary intake of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in children - a workshop report. Br J Nutr 2010;103(6):923-928.
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  13. Musa-Veloso, K., Binns, M. A., Kocenas, A. C., Poon, T., Elliot, J. A., Rice, H., Oppedal-Olsen, H., Lloyd, H., and Lemke, S. Long-chain omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid dose-dependently reduce fasting serum triglycerides. Nutr Rev 2010;68(3):155-167.
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  15. Su KP, Huang SY, Chiu CC, et al. Omega-3 fatty acids in major depressive disorder. A preliminary double-blind, placebo-controlled trial. Eur.Neuropsychopharmacol. 2003;13(4):267-271.

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The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

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