An analysis based on data from the Norwegian Women and Cancer Study (NOWAC) with regards to the dangers of persistent organic pollutants (POPs) in cod liver came to the conclusion that "in Norwegian women, fish liver consumption was not associated with an increased cancer risk in breast, uterus, or colon. In contrast, a decreased risk for total cancer was found."[65]

Other suspected health benefits of omega-3s and fish are less well established and need further study. They include suggestions of a reduced risk of breast cancer, colorectal cancer and possibly advanced prostate cancer, all related to eating fish rather than taking supplements. Some observational studies have associated omega-3s to a lower risk of cognitive decline, Alzheimer’s disease and dementia, as well as age-related macular degeneration.
The three types of omega-3s are APA, EPA and DHA. The first is a medium-chain fatty acid and must be converted into EPA before being synthesized by the body, and only about 1 percent of the APA consumed is able to be converted. EPA and DHA are already in a form ready to be synthesized (and are the subject of most scientific research regarding omega-3s).
There are numerous omega-3 sources with varying proportions of EPA and DHA, and the balance of EPA and DHA in a supplement influences the actions of these fats in the body. For more information about the different types of omega-3 sources and which are most suited for your individual needs, read our page on the different types of omega-3 supplements
Causing unsafe conditions. Fish oil may increase the risk of bleeding, which can lead to an unsafe condition. Excessive bleeding inside the body may also lead to conditions such as ulcers or liver disease which could be quite dangerous. Be aware of the signs and symptoms of this condition such as bruising easily or nosebleeds which could be a sign that you are developing this condition. If you begin to bleed more easily than usual then you should reduce the amount of fish oil you take regularly to reduce this condition.

Makrides et al. (25) Double-blind, placebo-controlled, randomized 2399 (n = 1197 supplemented, n = 1202 placebo; 726 children were followed up with) DHA (fish-oil capsules providing 800 mg/d DHA) Supplementation did not result in lower levels of postpartum depression in mothers or improved cognitive and language development in offspring during early childhood
Fish oil contamination even among “molecularly distilled” brands and those aimed at children is a widespread problem. One study in California tested 10 common brands and found PCBs — toxic industrial pollutants that have contaminated our oceans — in all of them. Some had 70 times the PCBs of other ones and 240x the toxicity. In another study, researchers tested 13 over-the-counter children’s dietary supplements containing fish oil for PCBs. PCBs were detected in all products. Our family takes algae-derived omega-3 (DHA/EPA) capsules, which are bioequivalent to fish oil capsules. Algae are actually the source where fish get their omega-3 content, so we skip the contaminated middle man (or, fish, in this case) and the neurotoxins that come with them given how polluted our oceans are now. I highly recommend parents do their research on what studies show about fish oil contamination and not just trust the labels, as well as consider algae-derived omega-3 capsules as more healthful bioequivalent to fish oil.
Muñoz MA, Liu W, Delaney JA, Brown E, Mugavero MJ, Mathews WC, Napravnik S, Willig JH, Eron JJ, Hunt PW, Kahn JO, Saag MS, Kitahata MM, Crane HM. Comparative effectiveness of fish oil versus fenofibrate, gemfibrozil, and atorvastatin on lowering triglyceride levels among HIV-infected patients in routine clinical care. J Acquir Immune Defic Syndr 2013;64(3):254-60. View abstract.

Wohl, D. A., Tien, H. C., Busby, M., Cunningham, C., Macintosh, B., Napravnik, S., Danan, E., Donovan, K., Hossenipour, M., and Simpson, R. J., Jr. Randomized study of the safety and efficacy of fish oil (omega-3 fatty acid) supplementation with dietary and exercise counseling for the treatment of antiretroviral therapy-associated hypertriglyceridemia. Clin.Infect.Dis. 11-15-2005;41(10):1498-1504. View abstract.

Mozaffarian D, Marchioli R, Macchia A, Silletta MG, Ferrazzi P, Gardner TJ, Latini R, Libby P, Lombardi F, O'Gara PT, Page RL, Tavazzi L, Tognoni G; OPERA Investigators. Fish oil and postoperative atrial fibrillation: the Omega-3 Fatty Acids for Prevention of Post-operative Atrial Fibrillation (OPERA) randomized trial. JAMA 2012;308(19):2001-11. View abstract.
Hamazaki, K., Itomura, M., Huan, M., Nishizawa, H., Sawazaki, S., Tanouchi, M., Watanabe, S., Hamazaki, T., Terasawa, K., and Yazawa, K. Effect of omega-3 fatty acid-containing phospholipids on blood catecholamine concentrations in healthy volunteers: a randomized, placebo-controlled, double-blind trial. Nutrition 2005;21(6):705-710. View abstract.

EPA and DHA are vital nutrients and may be taken to maintain healthy function of the following: brain and retina: DHA is a building block of tissue in the brain and retina of the eye. It helps with forming neural transmitters, such as phosphatidylserine, which is important for brain function. DHA is found in the retina of the eye and taking DHA may be necessary for maintaining healthy levels of DHA for normal eye function.
Bo and I worked with Dr. Harris many years ago to measure the impact of eating one Omega Cookie® daily on the study participants’ omega-3 index levels, and we recently ran into him at ISFFAL. At the conference, we remeasured our omega-3 index and omega-6/omega-3 ratios, and a few weeks later, we got our results in the mail. For the two of us, it was exciting to get another concrete measure of how our daily omega-3 consumption impacted our scores. For the record, we take one vial of Omega Restore™ per night and frequently sneak an Omega Heaven® or Omega Cookie during the day.
^ Jump up to: a b c Aung T, Halsey J, Kromhout D, Gerstein HC, Marchioli R, Tavazzi L, Geleijnse JM, Rauch B, Ness A, Galan P, Chew EY, Bosch J, Collins R, Lewington S, Armitage J, Clarke R (March 2018). "Associations of Omega-3 Fatty Acid Supplement Use With Cardiovascular Disease Risks: Meta-analysis of 10 Trials Involving 77 917 Individuals". JAMA Cardiology. 3 (3): 225–34. doi:10.1001/jamacardio.2017.5205. PMC 5885893. PMID 29387889.
Wohl, D. A., Tien, H. C., Busby, M., Cunningham, C., Macintosh, B., Napravnik, S., Danan, E., Donovan, K., Hossenipour, M., and Simpson, R. J., Jr. Randomized study of the safety and efficacy of fish oil (omega-3 fatty acid) supplementation with dietary and exercise counseling for the treatment of antiretroviral therapy-associated hypertriglyceridemia. Clin.Infect.Dis. 11-15-2005;41(10):1498-1504. View abstract.
Unintended weight loss is a problem that many patients with AD may face, and EPA+DHA supplementation has had a positive effect on weight gain in patients with AD. In a study using EPA+DHA supplementation, patients' weight significantly increased by 0.7 kg in the EPA+DHA treatment group at 6 mo (P = 0.02) and by 1.4 kg at 12 mo (P < 0.001) and was observed mainly in patients with a BMI <23 at the study start (54). This means that those patients with a lower BMI preferentially gained weight compared with those patients already with a higher BMI.

Bianconi, L., Calo, L., Mennuni, M., Santini, L., Morosetti, P., Azzolini, P., Barbato, G., Biscione, F., Romano, P., and Santini, M. n-3 polyunsaturated fatty acids for the prevention of arrhythmia recurrence after electrical cardioversion of chronic persistent atrial fibrillation: a randomized, double-blind, multicentre study. Europace. 2011;13(2):174-181. View abstract.
On September 8, 2004, the U.S. Food and Drug Administration gave "qualified health claim" status to EPA and DHA omega−3 fatty acids, stating, "supportive but not conclusive research shows that consumption of EPA and DHA [omega−3] fatty acids may reduce the risk of coronary heart disease".[98] This updated and modified their health risk advice letter of 2001 (see below).
When taking fish oil, more is not always better. Remember that you want it to stay in a balanced ratio with omega-6 fats. For most people, I recommend a 1,000-milligram dose of fish oil daily as a good amount and the most scientifically studied dosage. I highly recommend not taking more than that unless directed to under the supervision of a doctor.
Dr. Holub has provided the questions and answers for several emails he has received over the years regarding omega-3 fatty acids for health.  If you have a question regarding omega-3, it is likely that Dr. Holub has answered it either here in this section, or elsewhere on the site (e.g. check the scientific overview section for general questions regarding omega-3).  To quickly find your answer, please use our search bar located in the top right section of this page.  After searching our site, and  you still cannot find the answer to your question, we invite you to ask Dr. Holub a question here.
Although results from studies regarding the disease processes of AD seem to be promising, there are conflicting data regarding the use of omega-3 fatty acids in terms of cognitive function. Neuropsychiatric symptoms accompany AD from early stages and tend to increase with the progression of the disease (55). An analysis of 174 patients randomized to a placebo group or to a group with mild to moderate AD (MMSE score ≥15) treated with daily DHA (1.7 g) and EPA (0.6 g) found that at 6 mo, the decline in cognitive function did not differ between the groups. Yet, in a subgroup with very mild cognitive dysfunction (n = 32, MMSE score >27), they observed a significant reduction in the MMSE decline rate in the DHA+EPA-supplemented group compared with the placebo group (47). Another study that looked at DHA supplementation in individuals with mild to moderate AD used the Alzheimer's Disease Assessment Scale–Cognitive subscale, which evaluates cognitive function on a 70-point scale in terms of memory, attention, language, orientation, and praxis. This study found that DHA supplementation had no beneficial effect on cognition during the 18-mo trial period for the DHA group vs. placebo (56).
Studies have also found that omega-3 fatty acids from fish oil are associated with improved survival rates for heart attack victims. A study published in the medical journal Circulation found that people who took a high dose of fish oil each for six months following the occurrence of a heart attack actually improved their hearts’ overall functioning and also reduced biomarkers of systemic inflammation. (20)
However, since the dosage of fish oil required for an ideal effect in the improvement of a patient is unknown, the Arthritis Center in the Department of Rheumatology at John Hopkins University considers including omega-3 fatty acids and fish oil in the treatment of arthritis as controversial. The University also cautions that arthritis patients must be wary of all the other side effects that can come from using fish oil. You can read more about arthritis on the web page of the Arthritis Foundation and the Arthritis Center.
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.
The three types of omega-3s are APA, EPA and DHA. The first is a medium-chain fatty acid and must be converted into EPA before being synthesized by the body, and only about 1 percent of the APA consumed is able to be converted. EPA and DHA are already in a form ready to be synthesized (and are the subject of most scientific research regarding omega-3s).
Among the 16 studies comparing the effect of omega-3 PUFA treatment with that of the placebo,33,34,36,47-49,51-53,55-61 the main results revealed a significantly greater association of treatment with reduced anxiety symptoms in patients receiving omega-3 PUFA treatment than in those not receiving it (k, 16; Hedges g, 0.372; 95% CI, 0.032-0.712; P = .03; eFigure 3 in the Supplement). The meta-analysis of the subgroup focusing on non–placebo-controlled trials also showed a significantly greater association of treatment with reduced anxiety symptoms in patients receiving omega-3 PUFA treatment than in those not receiving it (k, 3; Hedges g, 0.399; 95% CI, 0.154-0.643; P = .001).35,50,54

If we want to deliver the benefits associated with EPA therapeutically, it is essential to optimise digestion and uptake. If we take EPA and DHA in their natural 1.5:1 ratio, it’s an uphill struggle for EPA because we know that DHA is more effectively absorbed and assimilated into cells. Delivering the benefits of EPA (for example, for cognitive function, mood and depression, inflammation regulation, heart health, skin health and so on), requires doses of EPA in excess of DHA, which determines the type of benefits obtained and the degree of the beneficial outcomes. The higher the ratio of EPA to DHA (meaning higher doses of EPA in relation to DHA), the more likely that EPA will be digested and absorbed, ready to meet the body’s high demands for this important nutrient.
In fact, dietary fat intake has been among the most widely studied dietary risk factors for breast and prostate cancers. Two studies from 2002 explain how omega-3 can protect against breast cancer. BRCA1 (breast cancer gene 1) and BRCA2 (breast cancer gene 2) are two tumor suppressor genes that, when functioning normally, help repair DNA damage, a process that also prevents tumor development.

Fish oil combined with fenofibrate has not been studied extensively in randomized controlled trials. Data to date, however, suggest that the combination is safe and effective.63,64 A recent randomized controlled trial of 100 patients with severe hypertriglyceridemia and HIV on highly active antiretroviral therapy showed that a regimen of fenofibrate and 3 g/d of fish oil for 8 weeks was well tolerated. The median baseline triglyceride level of 650 mg/dL was reduced by 65%.63 Another recent randomized, 2 month, double-blind, placebo-controlled trial, which was set up to assess the safety and efficacy of fenofibrate with 4 g of fish oil, showed that in the 81 patients assigned to combination therapy, triglyceride levels were reduced by 61%. Therapy was well-tolerated without significant adverse reactions at 8 weeks or at the end of a 2-year open label extension.64 The combination of fish oil and niacin requires further study.
In 2016, AHRQ reviewed 143 studies that evaluated the effects of giving omega-3 supplements to pregnant or breastfeeding women or giving formulas with added DHA to infants. They found that when women took omega-3 supplements during pregnancy, their babies’ birth weight was slightly higher, but the risk of an undesirably low birth weight did not change. Also, when women took omega-3 supplements during pregnancy, their pregnancies lasted a little longer, but there was no effect on the risk of premature birth. Omega-3s were not found to have effects on any other aspects of the mothers’ or infants’ health or the infants’ long-term development. Aspects of the infants’ health that were not shown to be affected by omega-3s include growth after birth, visual acuity, long-term neurological and cognitive development, and the risks of autism, ADHD, learning disorders, and allergies.
There have been numerous clinical trials looking mainly at death, stroke, and cardiac outcomes related to omega 3 consumption, either in food or in supplements. Now the Cochrane Library has published the largest systematic review of these studies to date. Unfortunately, the review shows little benefit from consuming omega 3 fatty acid. This is a fairly extensive review with good statistical power:
Sekikawa, A., Curb, D., Ueshima, H., El-Saed, A., Kadowaki, T., Abbott, R. D., ... Kuller, L. H. (2008 August 5). Marine-derived n-3 fatty acids and atherosclerosis in Japanese, Japanese Americans, and Whites: a cross-sectional study. Journal of the American College of Cardiology 52(6), 417–424. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2736602/
Cashew nuts are a versatile, creamy nut, eaten on their own as a snack or used as a base for many vegan cheese substitutes. RXBAR, a healthy alternative to the standard sugar-loaded snack bar, uses cashews for several of its flavor varieties. And with delicious (and kid-friendly!) flavors like gingerbread, chocolate chip, or “Berry Blast,” these bars are a tasty way to add more cashews to any diet.
Boucher, O., Burden, M. J., Muckle, G., Saint-Amour, D., Ayotte, P., Dewailly, E. ... Jacobson, J. L.. (2011, May). Neurophysiologic and neurobehavioral evidence of beneficial effects of prenatal omega-3 fatty acid intake on memory function at school age. American Journal of Clinical Nutrition 93(5), 1025-1037. Retrieved from http://ajcn.nutrition.org/content/93/5/1025.full

Fish oil is also commonly used to treat conditions such as Rheumatoid arthritis, high blood pressure, ADHD, menstrual pain, hardening of the arteries or kidney problems. These conditions can be improved by improving blood flow, which omega-3 fatty acids in the blood stream. There is also some evidence that fish oil may help with conditions such as chest pain, liver disease, migraine prevention, gum infections, breast pain, and muscle soreness due to exercise, skin rashes and stomach ulcers.
Fish oil can be obtained from eating fish or by taking supplements. Fish that are especially rich in the beneficial oils known as omega-3 fatty acids include mackerel, herring, tuna, salmon, cod liver, whale blubber, and seal blubber. Two of the most important omega-3 fatty acids contained in fish oil are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Make sure to see separate listings on EPA and DHA, as well as Cod Liver Oil, and Shark Liver Oil.
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