Unsafe for children. Fish oil supplements are not considered safe for children. Too much of this fat in their system can lead to a chemical imbalance in the brain which could stunt healthy growth and development. Because of this, and the possible exposure to polychlorinated biphenyls, methylmercury and other toxins which are found in some sources of fish, it is not recommended that women who are pregnant take excessive amounts of fish oil. Servings of fish should be limited to six ounces per week and they should refrain from using fish oil or other fatty acid supplement pills. Children should not consume more than two ounces of fish per week to avoid overexposure to these chemicals. Now you know although fish oil can benefit human beings a lot, fish oil side effects should never be neglected for the sake of your safety. 
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.

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


Another recent study shows that fatty fish consumption can cut the risk of eye-diabetes complications. The researches tracked the seafood consumption of about 3,600 diabetic men and women between the ages of 55 and 80 for nearly five years. The researchers found that people who regularly consumed 500 milligrams each day of omega-3 fatty acid in their diets (equal to two servings of fatty fish per week) were 48 percent less likely to develop diabetic retinopathy than those who consumed less. (23)
High blood pressure. Fish oil seems to slightly lower blood pressure in people with moderate to very high blood pressure. Some types of fish oil might also reduce blood pressure in people with slightly high blood pressure, but results are inconsistent. Fish oil seems to add to the effects of some, but not all, blood pressure-lowering medications. However, it doesn't seem to reduce blood pressure in people with uncontrolled blood pressure who are already taking blood pressure-lowering medications.
Damage to the kidneys caused the drug cyclosporine. Cyclosporine is a medication that reduces the chance of organ rejection after an organ transplant. Taking fish oil seems to prevent kidney damage in people taking this drug. Fish oil also seems to improve kidney function during the recovery phase following the rejection of a transplanted organ in people taking cyclosporine.
Some studies suggest that people who get higher amounts of omega-3s from foods and dietary supplements may have a lower risk of breast cancer and perhaps colorectal cancer. More research is needed to confirm this possible link. Whether omega-3s affect the risk of other cancers is not clear. Clinical trials to examine this possibility are in progress.
^ 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.

The human body can make most of the types of fats it needs from other fats or raw materials. That isn’t the case for omega-3 fatty acids (also called omega-3 fats and n-3 fats). These are essential fats—the body can’t make them from scratch but must get them from food. Foods high in Omega-3 include fish, vegetable oils, nuts (especially walnuts), flax seeds, flaxseed oil, and leafy vegetables.

If you’re not able to get enough fish oil benefits through your diet, fish oil supplements can be a good option. Fish oil side effects can include belching, bad breath, heartburn, nausea, loose stools, rash and nosebleeds, but in my experience, taking a high-quality fish oil supplement can reduce the likelihood of any unwanted side effects. It’s also a good idea to take fish oil with meals to reduce side effects.
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.
We are now fortunate to understand how these fats work in combination and in isolation, how they are digested, absorbed and utilised in the body, so we are able to tailor different blends of EPA and DHA according to the health benefits we are seeking to achieve. At Igennus, we have long specialised in the role of the omega-3 fatty acid EPA in clinical nutrition, as a powerful tool in the patient’s ‘toolkit’ for helping to regulate inflammation by restoring several biological markers, known as the omega-6 to omega-3 ratio and AA to EPA ratio. Before we discuss the therapeutic role of EPA in nutritional medicine, here’s a very brief summary of the role of both EPA and DHA in health throughout life.
The health benefits of fish oil can be incredible for the body’s largest organ, the skin. This source of essential fats improves the health and beauty of human skin in several ways. Fish oil benefits and nourishes the skin with fats and contributes fat-soluble vitamins that help skin maintain a smooth, elastic texture. There is also evidence that fish oil prevents wrinkles and works against the aging process.
Schilling, J., Vranjes, N., Fierz, W., Joller, H., Gyurech, D., Ludwig, E., Marathias, K., and Geroulanos, S. Clinical outcome and immunology of postoperative arginine, omega-3 fatty acids, and nucleotide-enriched enteral feeding: a randomized prospective comparison with standard enteral and low calorie/low fat i.v. solutions. Nutrition 1996;12(6):423-429. View abstract.
For rheumatoid arthritis, one systematic review found consistent, but modest, evidence for the effect of marine n−3 PUFAs on symptoms such as "joint swelling and pain, duration of morning stiffness, global assessments of pain and disease activity" as well as the use of non-steroidal anti-inflammatory drugs.[35] The American College of Rheumatology has stated that there may be modest benefit from the use of fish oils, but that it may take months for effects to be seen, and cautions for possible gastrointestinal side effects and the possibility of the supplements containing mercury or vitamin A at toxic levels. The National Center for Complementary and Integrative Health has concluded that "[n]o dietary supplement has shown clear benefits for rheumatoid arthritis", but that there is preliminary evidence that fish oil may be beneficial, but needs further study.[36]
Gajos G1, Rostoff P, Undas A, et al. Effects of polyunsaturated omega-3 fatty acids on responsiveness to dual antiplatelet therapy in patients undergoing percutaneous coronary intervention: the OMEGA-PCI (OMEGA-3 fatty acids after pci to modify responsiveness to dual antiplatelet therapy) study. J Am Coll Cardiol. 2010 Apr 20;55(16):1671-8. View abstract.
In 1964 it was discovered that enzymes found in sheep tissues convert omega−6 arachidonic acid into the inflammatory agent called prostaglandin E2[71] which both causes the sensation of pain and expedites healing and immune response in traumatized and infected tissues.[72] By 1979 more of what are now known as eicosanoids were discovered: thromboxanes, prostacyclins, and the leukotrienes.[72] The eicosanoids, which have important biological functions, typically have a short active lifetime in the body, starting with synthesis from fatty acids and ending with metabolism by enzymes. If the rate of synthesis exceeds the rate of metabolism, the excess eicosanoids may, however, have deleterious effects.[72] Researchers found that certain omega−3 fatty acids are also converted into eicosanoids, but at a much slower rate. Eicosanoids made from omega−3 fatty acids are often referred to as anti-inflammatory, but in fact they are just less inflammatory than those made from omega−6 fats. If both omega−3 and omega−6 fatty acids are present, they will "compete" to be transformed,[72] so the ratio of long-chain omega−3:omega−6 fatty acids directly affects the type of eicosanoids that are produced.[72]
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.

In addition, there was 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 adolescent subgroup (aged <18 years) (k, 3; Hedges g, 0.020; 95% CI, –0.209 to 0.250; P = .86),48,53,57 in the adult subgroup (aged ≥18 years but <60 years) (k, 11; Hedges g, 0.388; 95% CI, –0.012 to 0.788; P = .06),33,35,36,47,49-51,54-56,59 or in the elderly subgroup (aged ≥60 years) (k, 3; Hedges g, –0.112; 95% CI, –0.406 to 0.181; P = .45).52,58,60 These insignificant results might be due to the smaller sample sizes in each subgroup.


Corresponding Author: Yutaka J. Matsuoka, MD, PhD, Division of Health Care Research, Center for Public Health Sciences, National Cancer Center Japan, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan (yumatsuo@ncc.go.jp); Kuan-Pin Su, MD, PhD, China Medical University Hospital, No. 2, Yude Road, North District, Taichung City, Taiwan 404 (cobolsu@gmail.com).
Belalcazar, L. M., Reboussin, D. M., Haffner, S. M., Reeves, R. S., Schwenke, D. C., Hoogeveen, R. C., Pi-Sunyer, F. X., and Ballantyne, C. M. Marine omega-3 fatty acid intake: associations with cardiometabolic risk and response to weight loss intervention in the Look AHEAD (Action for Health in Diabetes) study. Diabetes Care 2010;33(1):197-199. View abstract.
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.
If, however, we want to target the actions and benefits of either fat for more intensive support or clinical use, we need to alter the natural 1.5:1 EPA:DHA ratio found in most omega-3 sources such as fish oil – which is when concentrated supplements are especially useful. Certain forms of omega-3 called ethyl-ester and re-esterified triglyceride give nature a helping hand – allowing us to achieve targeted ratios of specific fatty acids at high concentration and physiologically active doses.
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

Some studies suggest that people who get higher amounts of omega-3s from foods and dietary supplements may have a lower risk of breast cancer and perhaps colorectal cancer. More research is needed to confirm this possible link. Whether omega-3s affect the risk of other cancers is not clear. Clinical trials to examine this possibility are in progress.
Fish oil supplements came under scrutiny in 2006, when the Food Standards Agency in the UK and the Food Safety Authority of Ireland reported PCB levels that exceeded the European maximum limits in several fish oil brands,[60][61] which required temporary withdrawal of these brands. To address the concern over contaminated fish oil supplements, the International Fish Oil Standards (IFOS) Program, a third-party testing and accreditation program for fish oil products, was created by Nutrasource Diagnostics Inc. in Guelph, Ontario, Canada.[62]
While fish for dinner is one way to get EPA and DHA, most people don’t eat the suggested two to three servings of oily fish per week to reap the benefits of omega-3s. What’s more, there are extremely few food sources, aside from fish, that naturally provide EPA and DHA. With all the benefits that can come from fish oil, it’s no surprise that these supplements are increasing in popularity.
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
Have you also investigated the efficacy of purslane as a souce of Omega 3. Purslane (Portulaca olearacea) is a big part of the mountain vegetable diet of the Tujia minority in western Hunan (delicious), for example, and is consumed globally. Was glad to find it in local farmer’s market in California, and even happier to learn about its health benefits including Omega 3. The fish oil capsules are so huge… much better to sprinkle purslane or stir fry it…
Reduce Metabolic Syndrome Symptoms: The cluster of risk factors known as metabolic syndrome includes abdominal obesity, high blood sugar, high triglycerides, high blood pressure and low HDL cholesterol. These risk factors are indicative of a high chance you might develop heart disease, stroke or diabetes. Multiple studies have found omega-3 supplementation improve the symptoms of metabolic syndrome and may help to protect you from the related diseases. (22, 23, 24, 25)
Back in 2013, a study came out that made a lot of people concerned about fish oil supplements and cancer. The study, published in the Journal of the National Cancer Institute, showed that men who consume the largest amount of fish oil had a 71 percent higher risk of high-grade prostate cancer and a 43 percent increase in all types of prostate cancer. The study was conducted on 2,227 men, of which 38 percent of the men already had prostate cancer. (39)
For example, large predatory fish like shark, swordfish, king mackerel, tilefish and albacore tuna can contain high levels of methyl mercury, a toxin that would override any health benefit, especially for the developing brains of fetuses and young children as well as for adults, Dr. Nesheim and Marion Nestle, professor emerita of nutrition, food studies and public health at New York University, noted in 2014 in an editorial in the American Journal of Clinical Nutrition. (Levels of mercury and other contaminants in fish have since declined somewhat but are not negligible.)
Omega-3s are generally safe and well tolerated. Stomach upset and “fishy taste” have been the most common complaints, but they are less frequent now thanks to manufacturing methods that reduce impurities. Past concerns about omega-3s increasing the risk of bleeding have been largely disproven, but caution is still advised in people taking blood thinners or who are about to undergo surgery. As mentioned, caution is needed in people with bipolar disorder to prevent cycling to mania. Because omega-3s are important to brain development, and pregnancy depletes omega-3 in expectant mothers, supplementation should theoretically benefit pregnant women and their children. Fish consumption in pregnancy is supported by the FDA, but because we do not have long-term data on safety or optimal dosing of omega-3s in pregnancy, expectant mothers should consider omega-3 supplements judiciously.

Fish oil is useful in the treatment of arthritis, rheumatism, Raynaud’s symptoms and similar conditions. Using the fish oil can help in reducing the need for large dosages of NSAIDs (non-steroidal anti-inflammatory drugs). The Royal Adelaide Hospital and the University of Newcastle, located in Australia, have reported that fish oil has shown positive effects in the treatment of arthritis. In cases of osteoarthritis, fish oil can be helpful in reducing the impact of enzymes that destroy cartilage.
As a result, we depend on our diet to get the necessary Omega-3 fatty acids into our bodies. These two fatty acids work together in human health. DHA helps with cell membrane structure and assists in normal growth and development. While both EPA and DHA participate in key pathways of the immune system where they control key processes that support our health. Together they provide a number of important health benefits throughout our lifetime.

Abnormal cholesterol or fat levels in the blood (dyslipidemia). There is conflicting evidence about the effects of fish oil on cholesterol and fat levels in the blood. Some research shows that taking fish oil can lower triglyceride levels, low density lipoprotein (LDL or "bad") cholesterol, and increase high density lipoprotein (HDL or "good") cholesterol in people with abnormal cholesterol levels. However, other research shows that taking fish oil daily does not have this effect.
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