Additional side effects of fish oil supplements which have been reported include headache, short-term memory loss, depression, somatic disorders, and increased risk of colon cancer, nasopharyngitis, worsening of asthma symptoms, hemolytic anemia, decreased physical activity, increased appetite, a general uncomfortable feeling or increased blood pressure. The percentage of users that develop these side effects is not known. If these side effects become severe it is recommended that you stop using fish oil supplements.
In lab experiments, animals given krill showed improved navigation skills. What this means is that they achieved higher levels of cognition and memory required to navigate complex territory.28 In addition, research shows that animals supplemented with krill oil showed significantly fewer signs of depression and resignation. This improvement in mood was equivalent to the effect of the prescription anti-depressant drug imipramine (Tofranil®).29
It is believed that regular consumption of fish oil aids in boosting your immune system, thereby enabling you to resist the occurrence of common diseases like colds, cough, and the flu. Omega-3 fatty acids present in fish oil bolster the immune system by affecting the activity and amount of cytokines and eicosanoids present in our body. Researchers have also studied the effect of a fish meal and fish oil on the immune system of pigs and found that fish oil aided in the growth of the animals. Similar research conducted on mice at Taichung Veterans General Hospital, Taiwan, also gave positive results.
Various scales were used in these studies to evaluate the target outcome of anxiety symptoms: the Yale-Brown Obsessive-Compulsive Scale, Profile of Mood States, State-Trait Anxiety Inventory, Hamilton Anxiety Rating Scale, Generalized Anxiety Disorder questionnaire, Depression, Anxiety, and Stress Scales, Clinician-Administered Posttraumatic Stress Disorder Scale, Beck Anxiety Inventory, visual analog scale of anxiety, Impact of Event Scale–Revised, Conners score anxiety subscale, Neuropsychiatric Inventory, test anxiety severity, Hospital Anxiety and Depression Scale anxiety subscale, and Child Behavior Checklist anxiety subscale. The psychiatric and physical health conditions of the recruited participants also varied widely: general population without specific clinical conditions,36,47,51,55,60 participants with acute myocardial infarction,35 borderline personality disorder,2 mild to severe depression,59 obsessive-compulsive disorder,33 severe accidental injury,49 participants who were traumatized by disaster,54 participants with substance abuse disorder,34 women with premenstrual syndrome,56 children with attention-deficit/hyperactivity disorder,48,53 Alzheimer disease,58 generally healthy undergraduate college students but with test anxiety,61 Parkinson disease,52 and participants with Tourette syndrome.57 Sixteen studies compared the effect of omega-3 PUFA treatment with that of the placebo33,34,36,47-49,51-53,55-61; the other 3 studies were non–placebo controlled trials.35,50,54 The mean (SD) Jadad score of the recruited studies was 3.8 (1.0) (eTable in the Supplement).

Omega-3 fatty acids, which are found abundantly in fish oil, are increasingly being used in the management of cardiovascular disease. It is clear that fish oil, in clinically used doses (typically 4 g/d of eicosapentaenoic acid and docosahexaenoic acid) reduce high triglycerides. However, the role of omega-3 fatty acids in reducing mortality, sudden death, arrhythmias, myocardial infarction, and heart failure has not yet been established. This review will focus on the current clinical uses of fish oil and provide an update on their effects on triglycerides, coronary artery disease, heart failure, and arrhythmia. We will explore the dietary sources of fish oil as compared with drug therapy, and discuss the use of fish oil products in combination with other commonly used lipid-lowering agents. We will examine the underlying mechanism of fish oil’s action on triglyceride reduction, plaque stability, and effect in diabetes, and review the newly discovered anti-inflammatory effects of fish oil. Finally, we will examine the limitations of current data and suggest recommendations for fish oil use.
Gerber, J. G., Kitch, D. W., Fichtenbaum, C. J., Zackin, R. A., Charles, S., Hogg, E., Acosta, E. P., Connick, E., Wohl, D., Kojic, E. M., Benson, C. A., and Aberg, J. A. Fish oil and fenofibrate for the treatment of hypertriglyceridemia in HIV-infected subjects on antiretroviral therapy: results of ACTG A5186. J.Acquir.Immune.Defic.Syndr. 4-1-2008;47(4):459-466. View abstract.
Jump up ^ Martins, Julian G (2009). "EPA but Not DHA Appears to Be Responsible for the Efficacy of Omega-3 Long Chain Polyunsaturated Fatty Acid Supplementation in Depression: Evidence from a Meta-Analysis of Randomized Controlled Trials". Journal of the American College of Nutrition. 28 (5): 525–42. doi:10.1080/07315724.2009.10719785. PMID 20439549.
For those who can’t or choose not to eat fatty fish, or who have certain health issues, supplementation is a way to increase omega-3 levels. “There are some conditions that might respond well to supplementation, such as depression or cardiovascular risk factors, including elevated triglycerides,” explains Kathie Madonna Swift, MS, RDN, LDN.  If you're ooking to increase your omega-3 levels, Click here for six tips to finding the right supplement.
Maternal nutrition guidelines have always stressed a diet including sufficient caloric and protein requirements, but recently fatty acids have also been deemed important (17). This is partially due to the fact that EPA and DHA supplementation during pregnancy has been associated with multiple benefits for the infant (Table 1). During pregnancy, the placenta transfers nutrients, including DHA, from the mother to the fetus (18). The amount of omega-3 fatty acid in the fetus is correlated with the amount ingested by the mother, so it is essential that the mother has adequate nutrition (19). The 2010 U.S. Department of Health and Human Services dietary guidelines recommend that women who are pregnant or breastfeeding should “consume 8 to 12 ounces of seafood per week from a variety of seafood types” (12). Ingesting 8–12 oz of seafood per week, depending on the type of fish, is equivalent to ∼300–900 mg EPA+DHA per day. Unfortunately, this amount is not being met by most mothers in the United States and Canada, which means that infants many not be receiving adequate amounts of these vital nutrients in the womb (20).

Thanks for the informative article. You mentioned that those taking high doses of DHA should supplement it with trace amounts of GLA. What GLA source would you recommend, and how much per day? I will be taking around 3400 mg of epa and 2200 mg DHA per day. I've heard that Borage Oil is more potent in GLA than evening primrose, but that it can lead to increased clotting and increased risk of heart attack, stroke, etc due to increased thromboxane B2. The main reason I want to stay away from the primrose is because it is extremely rich in linoleic acid. Thanks.
Hanwell, H. E., Kay, C. D., Lampe, J. W., Holub, B. J., and Duncan, A. M. Acute fish oil and soy isoflavone supplementation increase postprandial serum (n-3) polyunsaturated fatty acids and isoflavones but do not affect triacylglycerols or biomarkers of oxidative stress in overweight and obese hypertriglyceridemic men. J Nutr 2009;139(6):1128-1134. View abstract.
Throughout their history, the Council for Responsible Nutrition and the World Health Organization have published acceptability standards regarding contaminants in fish oil. The most stringent current standard is the International Fish Oils Standard.[108][non-primary source needed] Fish oils that are molecularly distilled under vacuum typically make this highest-grade; levels of contaminants are stated in parts per billion per trillion.[citation needed][109]
Dry eye. Some clinical research shows that eating more fish oil is linked to a lower risk of getting dry eye syndrome in women. Other research shows that taking a specific fish oil product (PRN Dry Eye Omega Benefits softgels) daily modestly improves symptoms of dry eye such as pain, blurred vision, and sensitivity. Other research using other forms of fish oil products suggests that taking these supplements for 4-12 weeks modest improves some dry eye symptoms. However, the sensation of eye dryness is not always improved. Other research also shows that taking a specific combination products containing fish oil and other ingredients might improve some dry eye symptoms; however, this research is conflicted and poor quality.
CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.
Omega−3 fatty acids, also called ω−3 fatty acids or n−3 fatty acids,[1] are polyunsaturated fatty acids (PUFAs).[2][3] The fatty acids have two ends, the carboxylic acid (-COOH) end, which is considered the beginning of the chain, thus "alpha", and the methyl (-CH3) end, which is considered the "tail" of the chain, thus "omega". One way in which a fatty acid is named is determined by the location of the first double bond, counted from the tail, that is, the omega (ω-) or the n- end. Thus, in omega-3 fatty acids the first double bond is between the third and fourth carbon atoms from the tail end. However, the standard (IUPAC) chemical nomenclature system starts from the carboxyl end.
The use of DHA by persons with epilepsy could decrease the frequency of their seizures. Studies have shown that children with epilepsy had a major improvement, i.e. decrease in the frequency of their seizures, but another study showed mixed results with 57 adults taking DHA supplementation. The 57 subjects demonstrated a decreased frequency of seizures for the first six weeks of the study, but for some, it was just a temporary improvement (R).
“The review provides good evidence that taking long-chain omega 3 (fish oil, EPA or DHA) supplements does not benefit heart health or reduce our risk of stroke or death from any cause.  The most trustworthy studies consistently showed little or no effect of long-chain omega 3 fats on cardiovascular health. On the other hand, while oily fish is a healthy food, it is unclear from the small number of trials whether eating more oily fish is protective of our hearts. 
The FDA recommends that consumers do not exceed more than three grams per day of EPA and DHA combined, with no more than 2 grams from a dietary supplement.[56] This is not the same as 3000 mg of fish oil. A 1000 mg pill typically has only 300 mg of omega-3; 10 such pills would equal 3000 mg of omega-3. According to the European Food Safety Authority's (EFSA) Panel on Dietetic Products, Nutrition and Allergies, supplementation of 5 grams of EPA and DHA combined does not pose a safety concern for adults.[57] Dyerberg studied healthy Greenland Inuit and found an average intake of 5.7 grams of omega-3 EPA per day; among other effects these people had prolonged bleeding times, i.e., slower blood clotting.[58]
It seems that infancy and childhood are some of the most important periods of time in a person’s life to get plenty omega-3s in their diet, probably because of the amount of long-chain fatty acids found in the brain and retina. It’s crucial for developing babies and children to get a good amount of DHA and EPA so their brains and eyes develop fully and properly. (78)
Irish AB, Viecelli AK, Hawley CM, et al; Omega-3 Fatty Acids (Fish Oils) and Aspirin in Vascular Access Outcomes in Renal Disease (FAVOURED) Study Collaborative Group. Effect of fish oil supplementation and aspirin use on arteriovenous fistula failure in patients requiring hemodialysis: A randomized clinical trial. JAMA Intern Med. 2017;177(2):184-193. View abstract.
Despite this one study, you should still consider eating fish and other seafood as a healthy strategy. If we could absolutely, positively say that the benefits of eating seafood comes entirely from omega-3 fats, then downing fish oil pills would be an alternative to eating fish. But it’s more than likely that you need the entire orchestra of fish fats, vitamins, minerals, and supporting molecules, rather than the lone notes of EPA and DHA.

Jump up ^ Ilse Schreiber: Die Schwestern aus Memel (1936), quoted, and extract translated in: Strzelczyk, Florentine (2014). "16: 'Fighting against Manitou': German Identity and Ilse Schreiber's Canada Novels Die Schwestern aus Memel (1936) and Die Flucht in Paradies (1939)". In McFarland, Rob; James, Michelle Stott. Sophie Discovers Amerika: German-Speaking Women Write the New World. Studies in German Literature Linguistics and Culture. 148. Boydell & Brewer. p. 207. ISBN 9781571135865. Hoffentlich zogen die Eltern in eine Gegend, wo es recht viele Eingeborene gab. Indianer, die nur von Jagd und Fischfang leben. Ach, und womöglich Eskimos, die sich mit Tran einschmieren, um sich gegen die Kälte zu schützen und rohes Fleisch essen [...]. [She hoped her parents would move to an area where there were many aboriginals. Indians who live solely by hunting and fishing. Oh, and if possible Eskimos who smear themselves with fish oil to protect themselves from the cold, and who eat raw meat.]
Three omega−3 fatty acids are important in human physiology, α-linolenic acid (18:3, n-3; ALA), eicosapentaenoic acid (20:5, n-3; EPA), and docosahexaenoic acid (22:6, n-3; DHA).[67] These three polyunsaturates have either 3, 5, or 6 double bonds in a carbon chain of 18, 20, or 22 carbon atoms, respectively. As with most naturally-produced fatty acids, all double bonds are in the cis-configuration, in other words, the two hydrogen atoms are on the same side of the double bond; and the double bonds are interrupted by methylene bridges (-CH
The contents displayed within this public group(s), such as text, graphics, and other material ("Content") are intended for educational purposes only. The Content is not intended to substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your healthcare provider with any questions you may have regarding your medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read in a public group(s).
Jump up ^ Bloch MH, Qawasmi A (October 2011). "Omega-3 fatty acid supplementation for the treatment of children with attention-deficit/hyperactivity disorder symptomatology: systematic review and meta-analysis". Journal of the American Academy of Child and Adolescent Psychiatry. 50 (10): 991–1000. doi:10.1016/j.jaac.2011.06.008. PMC 3625948. PMID 21961774.
Samsonov, M. A., Vasil'ev, A. V., Pogozheva, A. V., Pokrovskaia, G. R., Mal'tsev, G. I., Biiasheva, I. R., and Orlova, L. A. [The effect of a soy protein isolate and sources of polyunsaturated omega-3 fatty acids in an anti-atherosclerotic diet on the lipid spectrum of blood serum and immunological indicators in patients with ischemic heart disease and hypertension]. Vopr.Med Khim. 1992;38(5):47-50. View abstract.
The National Institutes of Health (NIH) has created a website, NIH Clinical Research Trials and You, to help people learn about clinical trials, why they matter, and how to participate. The site includes questions and answers about clinical trials, guidance on how to find clinical trials through and other resources, and stories about the personal experiences of clinical trial participants. Clinical trials are necessary to find better ways to prevent, diagnose, and treat diseases.
Three randomized trials assessing more than 600 patients with known malignant ventricular arrhythmia were carried out under the protection of implanted cardioverter defibrillator (ICD) therapy.41–43 In all 3 of the trials, 75% of the patients had ischemic heart disease, survived ventricular tachycardia or ventricular fibrillation and were randomized to 1 to 3 g/d of fish oil. In the first trial of its kind, 402 patients with ICDs were randomized to either a fish oil or an olive oil supplement.41 Although statistical significance was not reached, after approximately 1 year the primary end-point of time to first ICD cardioversion for ventricular tachycardia or fibrillation or death from any cause was longer in the fish oil group. This finding was not replicated in a trial of 200 patients who were randomized to either fish oil or a placebo and followed for a median of approximately 2 years.42 In fact, time to first ICD cardioversion was not changed and the incidence of recurrent ventricular tachycardia and fibrillation was more common in the group assigned to fish oil. In the largest trial, 546 patients were randomized to supplemental fish oil or a placebo and were followed for a mean period of 1 year.43 The primary outcome of the rate of ICD cardioversion or all-cause mortality was not reduced. It was concluded in a recent meta-analysis of these trials that fish oil did not have a protective effect.44
The differing actions of EPA and DHA, together with their competitive uptake, help to explain why studies that attempt to use standard fish oil therapeutically (where DHA and EPA are combined, in a natural ratio of approximately 1.5:1) are either less beneficial than expected, or even completely ineffective. Standard EPA/DHA fish oils are more suitable for everyday wellbeing, to compensate for a lack of fish in the diet and to meet a suggested intake.
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Preventing re-blockage of blood vessels after angioplasty, a procedure to open a closed blood vessel. Research suggests that fish oil decreases the rate of blood vessel re-blockage by up to 45% when given for at least 3 weeks before an angioplasty and continued for one month thereafter. But, when given for 2 weeks or less before angioplasty, it doesn't seem to have any effect.