The National High Blood Pressure Education Program in the United States has cautioned against inaccurate publicity of fish oil as an effective means of lowering high blood pressure in patients suffering from hypertension. According to its report, fish oil supplements lower blood pressure in a very small way in hypertensive patients. Research conducted at the Channing Laboratory in Boston has revealed that moderate doses of fish oil supplements have little effect on the condition of high blood pressure in normotensive people.
Several other analyses of the evidence have been done in the last few years (2012 or later), and like the 2018 analysis and the AHRQ report, most found little or no evidence for a protective effect of omega-3 supplements against heart disease. However, some earlier analyses suggested that omega-3s could be helpful. The difference between the newer conclusions and the older ones may reflect two changes over time: 
Heart disease. Eating fish can be effective for keeping people with healthy hearts free of heart disease. People who already have heart disease might also be able to lower their risk of dying from heart disease by eating fish. The picture is less clear for fish oil supplements. For people who already take heart medications such as a "statin" and those who already eat a decent amount of fish, adding on fish oil might not offer any additional benefit.
Omega-3 fatty acids have been shown to increase platelet responsiveness to subtherapeutic anticoagulation therapies, including aspirin. Recently, it was noted that patient response to aspirin for anticoagulation therapy is widely variable (45), and, thus, the number of patients with a low response to aspirin or aspirin resistance is estimated to range from <1% to 45%, depending on many variables. However, in patients with stable coronary artery disease taking low-dose aspirin, EPA+DHA supplementation has been proven to be as effective as aspirin dose escalation to 325 mg/d for anticoagulation benefits (45). The antiplatelet drug clopidogrel has also been associated with hyporesponsiveness in some patients. This could be attributed to poor patient compliance, differences in genes and platelet reactivity, variability of drug metabolism, and drug interactions. More importantly, in 1 study, patients receiving standard dual antiplatelet therapy (aspirin 75 mg/d and clopidogrel 600-mg loading dose followed by 75 mg/d) were assigned to either EPA+DHA supplementation or placebo. After 1 mo of treatment, the P2Y12 receptor reactivity index (an indicator of clopidogrel resistance) was significantly lower, by 22%, for patients taking EPA+DHA compared with patients taking placebo (P = 0.020) (46).
Although there was significant heterogeneity among the included studies (Cochran Q, 178.820; df, 18; I2, 89.934%; P < .001), the sensitivity test suggested that the main significant results of the meta-analysis would not change after removal of any of the included studies. However, through direct inspection of the forest plot, we detected the potential influence of some outliers, such as the studies by Sohrabi et al56 and Yehuda et al.61 These 2 studies evaluated anxiety symptoms with a visual analog scale of anxiety and test anxiety severity, which are seldom used in psychiatric research and lack a definite report to prove their equivalent sensitivity and specificity to some other frequently used anxiety rating scales, such as depression, anxiety, and stress scales or the Hamilton anxiety rating scale. Therefore, these studies might have affected the interpretation of the current meta-analysis.
Because patients with depression experience rapid shrinking of their hippocampus, many strategies for relieving depression focus on increasing new brain cell growth in that specific area of the brain.23 There’s now evidence that increasing omega-3 intake, especially DHA, may be an effective way of treating or preventing depression, partly by protecting the hippocampus from further shrinkage.23
Dioxins and PCBs may be carcinogenic at low levels of exposure over time. These substances are identified and measured in one of two categories, dioxin-like PCBs and total PCBs. While the U.S. FDA has not set a limit for PCBs in supplements, the Global Organization for EPA and DHA (GOED) has established a guideline allowing for no more than 3 picograms of dioxin-like PCBs per gram of fish oil. In 2012, samples from 35 fish oil supplements were tested for PCBs. Trace amounts of PCBs were found in all samples, and two samples exceeded the GOED‘s limit.[52] Although trace amounts of PCBs contribute to overall PCB exposure, Consumerlab.com claims the amounts reported by tests it ordered on fish oil supplements are far below those found in a single typical serving of fish.[52]
The results of several small studies had suggested that taking omega-3 supplements might help relieve symptoms of dry eye disease. However, a 2018 NIH-sponsored study that tested omega-3 supplements for a full year in a larger group (535 study participants) with moderate-to-severe dry eye disease found that the supplements were no more helpful than a placebo (an inactive substance).
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]
An 18-month study was published in 2014 that evaluated how borage seed oil — rich in GLA — and fish oil rich fared against each other in treating patients with rheumatoid arthritis. It was discovered that all three groups (one taking fish oil, one taking borage oil and one taking a combination of the two) “exhibited significant reductions” in disease activity, and no therapy outperformed the others. For all three, “meaningful clinical responses” were the same after nine months. (11)
Many people focus on the dosage of fish oil to take, like 1000 mg or 1200 mg, but it is the omega-3s that matter. This is where the benefits of fish oil are found. The two types of omega-3 fatty acids to focus on are EPA and DHA. These omega-3s are naturally found in oily fish like salmon, halibut, sardines and anchovies, and are the very reason why fish oil supplements have received such high praise.
Matsumura  K, Noguchi  H, Nishi  D, Hamazaki  K, Hamazaki  T, Matsuoka  YJ.  Effects of omega-3 polyunsaturated fatty acids on psychophysiological symptoms of post-traumatic stress disorder in accident survivors: a randomized, double-blind, placebo-controlled trial.  J Affect Disord. 2017;224:27-31. doi:10.1016/j.jad.2016.05.054PubMedGoogle ScholarCrossref
People used to believe that osteoporosis and osteoarthritis were the result of aging and reduced intake of calcium and milk products. Science has now shown that these bone and joint disorders are, in part, due to inflammation. Because of this, bones and joints are prime targets for the anti-inflammatory properties of omega-3 oils from both fish and krill.
Findings  In this systematic review and meta-analysis of 19 clinical trials including 2240 participants from 11 countries, improvement in anxiety symptoms was associated with omega-3 polyunsaturated fatty acid treatment compared with controls in both placebo-controlled and non–placebo-controlled trials. The anxiolytic effects of omega-3 polyunsaturated fatty acids were also stronger in participants with clinical conditions than in subclinical populations.

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).
First difference is in the area of omega-6 fatty acid metabolism. Whereas EPA is the inhibitor of the enzyme (D5D) that directly produces AA, DHA is an inhibitor of another key enzyme delta-6-desaturase (D6D) that produces the first metabolite from linoleic acid known as gamma linolenic acid or GLA (6). However, this is not exactly an advantage. Even though reduction of GLA will eventually decrease AA production, it also has the more immediate effect of reducing the production of the next metabolite known as dihomo gamma linolenic acid or DGLA. This can be a disaster as a great number of powerful anti-inflammatory eicosanoids are derived from DGLA. This is why if you use high-dose DHA it is essential to add back trace amounts of GLA to maintain sufficient levels of DGLA to continue to produce anti-inflammatory eicosanoids.
Aceite de Pescado, Acides Gras Oméga-3, Acides Gras Oméga 3, Acides Gras Oméga 3 Sous Forme Ester Éthylique, Acides Gras N-3, Acides Gras Polyinsaturés N-3, Acides Gras W3, ACPI, EPA/DHA Ethyl Ester, Ester Éthylique de l'AEP/ADH, Fish Body Oil, Herring Oil, Huile de Foie de Morue, Huile de Hareng, Huile de Menhaden, Huile de Poisson, Huile de Saumon, Huile de Thon, Huile Lipidique Marine, Huile Marine, Huiles Marines, Lipides Marins, Marine Lipid Concentrate, Marine Fish Oil, Marine Lipid Oil, Marine Lipids, Marine Oil, Marine Oils, Marine Triglyceride, Menhaden Oil, N-3 Fatty Acids, N3-polyunsaturated Fatty Acids, Omega 3, Oméga 3, Omega-3, Oméga-3, Omega-3 Fatty Acid Ethyl Ester, Omega-3 Fatty Acids, Omega 3 Fatty Acids, Omega-3 Marine Triglycerides, PUFA, Salmon Oil, Triglycérides Marins, Tuna Fish Oil, Tuna Oil, W-3 Fatty Acids.
Kabir, M., Skurnik, G., Naour, N., Pechtner, V., Meugnier, E., Rome, S., Quignard-Boulange, A., Vidal, H., Slama, G., Clement, K., Guerre-Millo, M., and Rizkalla, S. W. Treatment for 2 mo with n 3 polyunsaturated fatty acids reduces adiposity and some atherogenic factors but does not improve insulin sensitivity in women with type 2 diabetes: a randomized controlled study. Am.J.Clin.Nutr. 2007;86(6):1670-1679. View abstract.
Omega-3 fatty acids are frequently in the news regarding their health benefits (or doubts in some cases). Two types of omega-3s in particular - eicosapentaenoic acid (EPA) and docohexaenoic acid (DHA) – are known to be essential fatty acids. “Essential” refers to the fact that our cells need these fatty acids in order to function normally. But the body cannot make them from other fats, which means it’s “essential” we supply them in our diet or through supplementation.

The Cochrane researchers found that increasing long-chain omega 3 provides little if any benefit on most outcomes that they looked at. They found high certainty evidence that long-chain omega 3 fats had little or no meaningful effect on the risk of death from any cause. The risk of death from any cause was 8.8% in people who had increased their intake of omega 3 fats, compared with 9% in people in the control groups.
Fish oil supplements in our study averaged 473.3mg EPA + 243.1mg DHA in a single serving. These average values were stretched by outliers on both extremes of the spectrum. Nature Made Cod Liver Oil (50mg EPA/serving) and Schiff MegaRed Krill Oil (29mg DHA/serving) recorded category lows for the two omega-3 fatty acids. Ocean Blue Professional Omega-3 (1260mg EPA/serving) and Dr. Tobias Optimum Omega-3 Fish Oil (600mg DHA/serving), on the other hand, recorded category highs for EPA and DHA content.
So why is an excess of DHA detrimental and an excess of EPA useful? DHA has a larger structure with two extra carbons and two extra double bonds, so it literally takes up more space in cell membranes than EPA. On the one hand, this is important because DHA plays a structural role in maintaining the fluidity of cell membranes ( essential for the normal function of proteins, channels and receptors that are also embedded in the membrane), but if a cell membrane becomes too saturated with DHA it can become too fluid, which can have a negative effect on cell function. EPA, on the other hand, is constantly utilised and always in demand.
Fish oils might slow blood clotting. Taking fish oils along with medications that also slow clotting might increase the chances of bruising and bleeding.Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), diclofenac (Voltaren, Cataflam, others), ibuprofen (Advil, Motrin, others), naproxen (Anaprox, Naprosyn, others), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, warfarin (Coumadin), and others.
In a study published after the AHRQ report, scientists in Denmark gave high-dose fish oil supplements or placebos to 736 pregnant women during the third trimester of pregnancy. Children born to mothers who had taken fish oil were less likely to develop asthma or persistent wheezing in early childhood, and this was most noticeable in children whose mothers had low blood levels of EPA and DHA before they started to take the supplements. However, other studies that evaluated the effects of omega-3 supplementation during pregnancy on childhood asthma risk have had inconsistent results.
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Because patients with depression experience rapid shrinking of their hippocampus, many strategies for relieving depression focus on increasing new brain cell growth in that specific area of the brain.23 There’s now evidence that increasing omega-3 intake, especially DHA, may be an effective way of treating or preventing depression, partly by protecting the hippocampus from further shrinkage.23

Augood, C., Chakravarthy, U., Young, I., Vioque, J., de Jong, P. T., Bentham, G., Rahu, M., Seland, J., Soubrane, G., Tomazzoli, L., Topouzis, F., Vingerling, J. R., and Fletcher, A. E. Oily fish consumption, dietary docosahexaenoic acid and eicosapentaenoic acid intakes, and associations with neovascular age-related macular degeneration. Am J Clin Nutr 2008;88(2):398-406. View abstract.
The Japanese notably have the lowest levels of coronary heart disease mortality and atherosclerosis among developed nations — a phenomena that has been largely subscribed to diet. However, even within Japan, a 10-year study of over 41,000 people found that higher intakes of omega-3s were associated with lower risks of nonfatal coronary events (8). A more recent study also found that Japanese with higher omega-3 index levels (10%) had a lower risk of fatal coronary heart disease than those with a lower omega-3 index levels (8%) (9). The study begs the question of whether maybe even the Japanese have room to improve their omega-3 intake and whether 8% should be considered the lower limit of a desirable range.

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).
The number of presenters and the amount of information stuffed into an action-packed few days at times felt overwhelming, even for two dedicated omega-3 enthusiasts like us. But one important message did hit home: The omega-3 index could be a helpful indicator of various health risks, and we should all be paying closer attention to this measurement.
Jump up ^ Wang C, Harris WS, Chung M, Lichtenstein AH, Balk EM, Kupelnick B, Jordan HS, Lau J (July 2006). "n−3 Fatty acids from fish or fish-oil supplements, but not alpha-linolenic acid, benefit cardiovascular disease outcomes in primary- and secondary-prevention studies: a systematic review". The American Journal of Clinical Nutrition. 84 (1): 5–17. doi:10.1093/ajcn/84.1.5. PMID 16825676.
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.
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