The question is whether the observed cardiovascular benefits often found among fish eaters is due solely to the oils in fish or to some other characteristics of seafood or to still other factors common to those who eat lots of fish, like eating less meat or pursuing a healthier lifestyle over all. Whatever the answer, it does not seem to be fish oil supplements.

The European Journal of Neuroscience published a study in 2013 showing that fish oil reversed all anxiety-like and depression-like behavior changes induced in rats. This is an interesting study because it stresses the importance of supplementing with fish oil at “critical periods of brain development.” (10) This is exactly why I recommend giving fish oil to our kids from early on to help them so they won’t develop anxiety or depression later in life.
Results of studies investigating the role of LCPUFA supplementation and LCPUFA status in the prevention and therapy of atopic diseases (allergic rhinoconjunctivitis, atopic dermatitis and allergic asthma) are controversial; therefore, at the present stage of our knowledge (as of 2013) we cannot state either that the nutritional intake of n−3 fatty acids has a clear preventive or therapeutic role, or that the intake of n-6 fatty acids has a promoting role in context of atopic diseases.[64]
Results  In total, 1203 participants with omega-3 PUFA treatment (mean age, 43.7 years; mean female proportion, 55.0%; mean omega-3 PUFA dosage, 1605.7 mg/d) and 1037 participants without omega-3 PUFA treatment (mean age, 40.6 years; mean female proportion, 55.0%) showed an association between clinical anxiety symptoms among participants with omega-3 PUFA treatment compared with control arms (Hedges g, 0.374; 95% CI, 0.081-0.666; P = .01). Subgroup analysis showed that the association of treatment with reduced anxiety symptoms was significantly greater in subgroups with specific clinical diagnoses than in subgroups without clinical conditions. The anxiolytic effect of omega-3 PUFAs was significantly better than that of controls only in subgroups with a higher dosage (at least 2000 mg/d) and not in subgroups with a lower dosage (<2000 mg/d).
There was a significantly greater association of treatment with reduced anxiety symptoms in participants receiving omega-3 PUFAs than in those not receiving omega-3 PUFAs in the subgroup with an EPA percentage less than 60% (k, 11; Hedges g, 0.485; 95% CI, 0.017-0.954; P = .04; Figure 4)35,49,52,54-61 but no significant difference in the association of treatment with reduced anxiety symptoms between participants receiving omega-3 PUFAs and those not receiving omega-3 PUFAs in the subgroup with an EPA percentage of at least 60% (k, 9; Hedges g, 0.092; 95% CI, –0.102 to 0.285; P = .35) (Figure 4).33,34,36,47,48,50,51,53,60 There were no significantly different estimated effect sizes between these 2 subgroups by the interaction test (P = .13).
Children, in particular, seem to experience problems with sleep when they don’t get enough omega-3 fatty acids in their diets. In adults, low omega-3 levels are associated with obstructive sleep apnea. One reason for this may be that low omega-3s are linked to lower levels of melatonin, the hormone partly responsible for helping you to get to sleep in the first place.
Omega-3 Power is sourced from anchovies, sardines, and mackerel. These fish roam mostly in the mid-level of the ocean and have relatively short-lived lifespans. Because of this, they tend to accumulate fewer toxins. In addition, the fish oil in Omega-3 Power is put through the most thorough purification processes available. It includes screening for more than 250 potentially toxic chemicals, and at the same time, eliminates the “burpy” effects of crude fish oils. The result is the highest quality omega-3 supplement available on the market today.
Fish oil is a commonly used dietary supplement, with sales in the U.S. alone reaching $976 million in 2009.[48] Problems of quality have been identified in periodic tests by independent researchers of marketed supplements containing fish oil and other marine oils. These problems include contamination, inaccurate listing of EPA and DHA levels, spoilage and formulation issues.[49]

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)


There is some evidence that omega−3 fatty acids are related to mental health,[47] including that they may tentatively be useful as an add-on for the treatment of depression associated with bipolar disorder.[48] Significant benefits due to EPA supplementation were only seen, however, when treating depressive symptoms and not manic symptoms suggesting a link between omega−3 and depressive mood.[48] There is also preliminary evidence that EPA supplementation is helpful in cases of depression.[49] The link between omega−3 and depression has been attributed to the fact that many of the products of the omega−3 synthesis pathway play key roles in regulating inflammation (such as prostaglandin E3) which have been linked to depression.[50] This link to inflammation regulation has been supported in both in vitro[51] and in vivo studies as well as in meta-analysis studies.[33] The exact mechanism in which omega−3 acts upon the inflammatory system is still controversial as it was commonly believed to have anti-inflammatory effects.[52]
Evidence in the population generally does not support a beneficial role for omega−3 fatty acid supplementation in preventing cardiovascular disease (including myocardial infarction and sudden cardiac death) or stroke.[4][19][20][21] A 2018 meta-analysis found no support that daily intake of one gram of omega-3 fatty acid in individuals with a history of coronary heart disease prevents fatal coronary heart disease, nonfatal myocardial infarction or any other vascular event.[6] However, omega−3 fatty acid supplementation greater than one gram daily for at least a year may be protective against cardiac death, sudden death, and myocardial infarction in people who have a history of cardiovascular disease.[22] No protective effect against the development of stroke or all-cause mortality was seen in this population.[22] Eating a diet high in fish that contain long chain omega−3 fatty acids does appear to decrease the risk of stroke.[23] Fish oil supplementation has not been shown to benefit revascularization or abnormal heart rhythms and has no effect on heart failure hospital admission rates.[24] Furthermore, fish oil supplement studies have failed to support claims of preventing heart attacks or strokes.[7]
Abnormal rapid heart rhythms (ventricular arrhythmias). Population research suggests that eating a lot of fish has no effect on the risk for abnormal rapid heart rhythms. Clinical research is inconsistent. Some research shows that taking fish oil daily does not affect the risk for abnormal heart rhythms. But other research shows that taking fish oil for 11 months delays the development of the condition. However, overall, taking fish oil does not seem to reduce the risk of death in people with abnormal rapid heart rhythms.

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).


If a chicken eats a diet heavy in omega-3s — such as flaxseed and other nutrient-dense grains — its eggs will be fortified with higher levels of those healthy fatty acids. If you can afford a little extra expense, look for omega-3-enriched eggs from humanely raised chickens that roam free and forage for insects and plants, which give the eggs even further nutrients and health benefits.
Marine and freshwater fish oil vary in contents of arachidonic acid, EPA and DHA.[15] The various species range from lean to fatty and their oil content in the tissues has been shown to vary from 0.7% to 15.5%.[16] They also differ in their effects on organ lipids.[15] Studies have revealed that there is no relation between total fish intake or estimated omega−3 fatty acid intake from all fish, and serum omega−3 fatty acid concentrations.[17] Only fatty fish intake, particularly salmonid, and estimated EPA + DHA intake from fatty fish has been observed to be significantly associated with increase in serum EPA + DHA.[17]
Peroxides can be produced when fish oil spoils. A study commissioned by the government of Norway concluded there would be some health concern related to the regular consumption of oxidized (rancid) fish/marine oils, particularly in regards to the gastrointestinal tract, but there is not enough data to determine the risk. The amount of spoilage and contamination in a supplement depends on the raw materials and processes of extraction, refining, concentration, encapsulation, storage and transportation.[51] ConsumerLab.com reports in its review that it found spoilage in test reports it ordered on some fish oil supplement products.[52]
Brussels sprouts are a cruciferous vegetable bursting with vitamin K, vitamin C, and a healthy dose of omega-3 fatty acids. With their strong flavor and smell, however, they’re not always loved (or even tolerated) by children or adults with ADHD. If someone in your house considers sprouts the enemy, try this recipe — honey, cranberries, and parmesan cheese give these Brussels sprouts a sweet and savory flavor that even picky eaters love.

People with metabolic syndrome (the combination of central obesity, high blood pressure, disturbed lipid profile, and impaired glucose tolerance) are at increased risk of death from cardiovascular disease, diabetes, cancer, and other apparently “age-related” disorders. Because metabolic syndrome is closely associated with chronic low-grade inflammation, the powerful anti-inflammatory effects of omega-3 fats are especially important as a means of slowing or stopping the progression of this deadly disorder.
Omega AD study, Freund-Levi et al. (47) Double-blind, placebo-controlled, randomized 1741 DHA (1.7 g/d) and EPA (0.6 g/d) Decline in cognitive function did not differ between supplemented group and placebo group at 6 mo. However, patients with very mild cognitive dysfunction (n = 32, MMSE score >27) in the EPA+DHA-supplemented group had a significant reduction in MMSE score decline rate at 6 mo
Krill oil is joining the toolkit for fighting arthritis, thanks to its exceptional anti-inflammatory properties resulting from its phospholipid form of omega-3s. A study in mice with experimental arthritis showed that krill oil supplements reduced arthritis scores and markedly diminished joint swelling. When examined under a microscope, the animals’ joints were remarkably free of inflammatory infiltrates of immune system cells.85

LCn3s are long chain fatty acids from fish, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA is plant-based omega 3-alpha‐linolenic acid. Fatty acids are essentially chains of carbon atoms with an OOH group at one end. The available binding sites on the carbon atoms are filled with hydrogen atoms. If every binding site is occupied with a hydrogen, that is a saturated fatty acid. If instead of hydrogen atoms there is a double bond between two adjacent carbon atoms, that is an unsaturated fatty acid. If there are multiple double bonds, that is polyunsaturated. Omega 3 fatty acids are unsaturated, with a double bond between the third and fourth carbon atoms from the end opposite the OOH group.
Krauss-Etschmann et al. (26) Double-blind, placebo-controlled, randomized 311 DHA+EPA daily with either fish oil with DHA (0.5 g) and EPA (0.15 g) or with methyltetrahydrofolic acid (400 μg), both, or placebo, from gestation week 22 Fish-oil supplementation was associated with decreased levels of maternal inflammatory/TH1 cytokines and a decrease of fetal Th2-related cytokines
It can be challenging to get the appropriate intake of EPA and DHA through diet alone, even though EPA and DHA are produced by water plants such as algae and are prevalent in marine animals. A shorter chain omega-3 fatty acid, α-linolenic acid (ALA),6 is a prominent component of our diet as it is found in many land plants that are commonly eaten, but it does not provide the health benefits seen with EPA and DHA. Although it is possible for the body to convert ALA to EPA and DHA by enlongase and desaturase enzymes, research suggests that only a small amount can be synthesized in the body from this process (8). For example, 1 study suggested that only ∼2 to 10% of ALA is converted to EPA or DHA (9), and other studies found even less: Goyens et al. (10) found an ALA conversion of ∼7% for EPA, but only 0.013% for DHA; Hussein et al. (11) found an ALA conversion of only 0.3% for EPA and <0.01% for DHA.
Our scientists also focused on each oil’s freshness, measured by the degree of oxidation. Oxidation occurs in two phases: primary (measured by peroxide values) and secondary (measured by p-anisidine values). Total oxidation is formalized into a quantitative score, TOTOX. While Labdoor conducted tests of both primary and secondary oxidation, advances in rancidity testing confirm that added flavors–particularly added citrus flavors prevalent in liquid formulations–skew p-anisidine values and result in false positive outcomes. Until analytical techniques measuring p-anisidine values that are able to account for added flavors are established, Labdoor will use peroxide values as the primary indicator of freshness. All products recorded measurable levels of oxidation, with the average product recording a peroxide values of 3.7 meq/kg. 14/51 products recorded peroxide levels at or above the upper limit (10 meq/kg).
Fish oil seems to be a subject of controversy. Some people swear by it, and there are thousands of clinical trials out now trying to study what the latest and greatest thing about the supplement is. The Natural Standard does a really good job collecting and gathering data for those who are interested in delving through what fish oil may or may not be doing to us. Definitive answers, however, may take a little while to get.
Irving, G. F., Freund-Levi, Y., Eriksdotter-Jonhagen, M., Basun, H., Brismar, K., Hjorth, E., Palmblad, J., Vessby, B., Vedin, I., Wahlund, L. O., and Cederholm, T. Omega-3 fatty acid supplementation effects on weight and appetite in patients with Alzheimer's disease: the omega-3 Alzheimer's disease study. J Am Geriatr Soc 2009;57(1):11-17. View abstract.
We use cookies and similar technologies to improve your browsing experience, personalize content and offers, show targeted ads, analyze traffic, and better understand you. We may share your information with third-party partners for marketing purposes. To learn more and make choices about data use, visit our Advertising Policy and Privacy Policy. By clicking “Accept and Continue” below, (1) you consent to these activities unless and until you withdraw your consent using our rights request form, and (2) you consent to allow your data to be transferred, processed, and stored in the United States.

Before getting to know some of the fish oil side effects, you have to know more about fish oil, like its benefits and usages. Fish oil has become a popular supplement for athletes, as well as those looking to improve their overall health. Many claims have been made regarding the improvements to the body which can be made by using fish oil to increase the body's level of fatty omega-3 acids. Some of these claims have been backed up by studies, while others have not been proven with significant scientific evidence. There are also some precautions that need to be addressed if you will be taking fish oil regularly. People with certain health conditions may see a worsening of their symptoms if they increase their intake of fatty acids too quickly or with the wrong products.


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).
What about blood clotting? Circulating cells called platelets are critical in causing your blood to clot. When platelets are activated, they aggregate and cause clots. If these clots occur in particularly sensitive regions of your body, they can lead to a heart attack or stroke. EPA reduces platelet activation, an early step in platelet aggregation to help to reduce clotting. One study found that EPA was superior to DHA in decreasing platelet activation, a precursor to blood clotting.1
We included 79 RCTs (112,059 participants) in this review update and found that 25 were at low summary risk of bias. Trials were of 12 to 72 months’ duration and included adults at varying cardiovascular risk, mainly in high‐income countries. Most studies assessed LCn3 supplementation with capsules, but some used LCn3‐ or ALA‐rich or enriched foods or dietary advice compared to placebo or usual diet.
Nonetheless, large population studies with solid data both on the participants’ diets and causes of disease and death bolstered the beliefs that eating fish often was a heart-healthy practice linked to reduced rates of cardiovascular disease. For example, a comprehensive analysis conducted by Dr. Dariush Mozaffarian and Eric Rimm of the Harvard T.H. Chan School of Public Health found that eating two servings of fatty fish a week — equal to about two grams of omega-3 fatty acids — lowered the risk of death from heart disease by more than a third and total deaths by 17 percent.

Fish oil supplements vary in the amounts and ratios of DHA and EPA they contain. For example, salmon oil naturally contains more DHA than EPA; a supplement derived from algae may only contain DHA. Krill oil contains significant amounts of both EPA and DHA. Read the labels and remember whatever supplement you buy, it must have at least 600 mg of DHA.


Fish oil is oil derived from the tissues of oily fish. Fish oils contain the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), precursors of certain eicosanoids that are known to reduce inflammation in the body,[1][2] and have other health benefits, such as treating hypertriglyceridemia, although claims of preventing heart attacks or strokes have not been supported.[3][4][5][6] Fish oil and omega-3 fatty acids have been studied in a wide variety of other conditions, such as clinical depression,[7][8] anxiety,[9][10][11] cancer, and macular degeneration, yet benefits in these conditions have not been verified.[12]
To date, no studies have assessed mortality or nonfatal MI in diabetic patients treated with fish oil.52–54 A recent comprehensive meta-analysis analyzed the effect of fish oil supplements on metabolic parameters when added to usual care in patients with type 2 diabetes mellitus or impaired glucose tolerance.54 The meta-analysis included a total of 23 small, randomized trials with over 1000 patients that were assessed for lipid and insulin resistance parameters. At a mean follow-up of approximately 9 weeks, triglyceride reduction was accomplished but no significant changes were seen in total cholesterol, high-density lipoprotein-cholesterol, HgA1c levels, fasting glucose levels, fasting insulin, or in body weight. The largest randomized trial to date assessed approximately 400 patients with impaired glucose tolerance or insulin-dependent diabetes mel-litus, and as reflected in the larger meta-analysis, found no effect of moderate to high doses of fish oil on diabetic parameters.55 There are insufficient randomized data to comment on the combination of fish oil and specific diabetes medications and related mortality and/or morbidity.
A group out of India conducted a study published in Cancer Chemotherapy and Pharmacology based on the premise that “fish oil rich in n-3 polyunsaturated fatty acids has been preferred to chemosensitize tumor cells to anti-cancer drugs.” The study found that using 5-Fluorouracil (5-FU) to treat colorectal cancer along with fish oil increased the survival rate in carcinogen-treated animals. Researchers also found that the fish oil ameliorated hematologic depression, along with gastrointestinal, hepatic and renal toxicity caused by the 5-FU. (15)
The most extensive data of the effect of fish oil on lipoprotein subfractions are based on trials performed before the widespread use of statins. This data were aggregated over a decade ago in a meta-analysis of 16 randomized trials including over 1500 patients.17 In this analysis, low-density lipoprotein (LDL) was increased by an average of 5% and high-density lipoprotein was marginally changed. Although a shift toward less atherogenic, larger and more buoyant LDL particle composition has been shown,74 this has been offset by the observation that the number of apolipoprotein B 100 particles increases and may be more susceptible to oxidation.75 Increased conversion of remnant particles (intermediate density lipoprotein) to LDL has also been observed.76

Most Americans take in far more of another essential fat—omega-6 fats—than they do omega-3 fats. Some experts have raised the hypothesis that this higher intake of omega-6 fats could pose problems, cardiovascular and otherwise, but this has not been supported by evidence in humans. (4) In the Health Professionals Follow-up Study, for example, the ratio of omega-6 to omega-3 fats wasn’t linked with risk of heart disease because both of these were beneficial. (5) Many other studies and trials in humans also support cardiovascular benefits of omega-6 fats. Although there is no question that many Americans could benefit from increasing their intake of omega-3 fats, there is evidence that omega-6 fats also positively influence cardiovascular risk factors and reduce heart disease.
It is also believed that women who do not have a sufficient intake of EPA and DHA in their diet suffer from depression after childbirth, as there is a transfer of some amount of brain mass from the mother to the child in the last stages of pregnancy. Thus, it is very beneficial to consume fish oil either by eating fish or taking fish oil supplements, tablets, capsules, or pills during pregnancy for the overall development of the child and the well-being of the mother. However, it should be noted that fish oil obtained from the liver of the fish, example – cod liver oil, should not be consumed during pregnancy as cod liver oil is high in retinol and vitamin A, which are usually known to cause birth defects.

The Department of Ecology of the State of Washington has ranked various seafood based on its EPA and DHA concentrations. The highest-ranking seafood is mackerel, excluding King mackerel, that has a concentration of 1,790 milligrams of combined EPA and DHA per 100 grams, followed by salmon at 1,590; bluefin tuna has between 1173 and 1504 milligrams; sardines contain 980 milligrams; albacore tuna has 862 milligrams; bass has 640 milligrams; tuna has 630 milligrams; trout and swordfish have 580 milligrams; and walleye has 530 milligrams. Other seafood, which includes sea bass, clams, lobster, scallops, catfish, cod, pollock, crayfish and scallops contains between 200 and 500 milligrams of EPA and DHA per 100 grams. Breaded fish products rank lowest on the list with only 0.26 milligram per 100 grams.

Sangiovanni, J. P., Agron, E., Meleth, A. D., Reed, G. F., Sperduto, R. D., Clemons, T. E., and Chew, E. Y. {omega}-3 Long-chain polyunsaturated fatty acid intake and 12-y incidence of neovascular age-related macular degeneration and central geographic atrophy: AREDS report 30, a prospective cohort study from the Age-Related Eye Disease Study. Am J Clin Nutr 2009;90(6):1601-1607. View abstract.
×