Scientific studies have found that fish oil can help to prevent and kill various cancers, including colon, prostate and breast. (13a) Not only has research proven that it makes conventional cancer drugs more effective, but it’s also an effective stand-alone therapy in natural cancer treatment. Intravenous fish oil lipid emulsions, in particular, are rich in omega-3 polyunsaturated fatty acids, which exhibit anti-inflammatory and immunomodulatory effects. (13b)

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.

This constant sweeping motion of DHA also causes the breakup of lipid rafts in membranes (8). Disruption of these islands of relatively solid lipids makes it more difficult for cancer cells to continue to survive and more difficult for inflammatory cytokines to initiate the signaling responses to turn on inflammatory genes (9). In addition, the greater spatial characteristics of DHA increase the size of LDL particles to a greater extent compared to EPA. As a result, DHA helps reduce the entry of these enlarged LDL particles into the muscle cells that line the artery thus reducing the likelihood of developing atherosclerotic lesions (10). Thus the increased spatial territory swept out by DHA is good news for making certain areas of membranes more fluid or lipoprotein particles larger, even though it reduces the benefits of DHA in competing with AA for key enzymes important in the development of cellular inflammation.
Pro Omega 3 Intensive Formula is a more convenient source of EPA and DHA than regular marine fish oils for those who would like to supplement their diets with higher amounts of these important omega 3 fatty acids. Our formula contains concentrated marine fish oil, providing enriched levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Plus, it’s lower in saturated fatty acids than regular marine fish oil. For those who don’t eat fish or want to add more omega to their diet, Omega 3 supplements are a convenient way of incorporating these important nutrients into your everyday life. This fish oil supplement is strictly screened for the absence of any toxic metals and chemicals, and is completely free of cholesterol. The oil is carefully processed and handled to avoid oxidation.†
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.
DHA is especially vital for infant and child brain and nervous system development, as well as visual function. In older children, high DHA levels have been shown to improve learning ability, while deficiencies have been linked to learning problems and ADHD. And in adults, some studies have shown that DHA helps protect against cognitive decline and Alzheimer’s disease.
Jump up ^ Siscovick DS, Barringer TA, Fretts AM, Wu JH, Lichtenstein AH, Costello RB, Kris-Etherton PM, Jacobson TA, Engler MB, Alger HM, Appel LJ, Mozaffarian D (2017). "Omega−3 Polyunsaturated Fatty Acid (Fish Oil) Supplementation and the Prevention of Clinical Cardiovascular Disease: A Science Advisory From the American Heart Association". Circulation. 135 (15): e867–84. doi:10.1161/CIR.0000000000000482. PMID 28289069.

Haberka, M., Mizia-Stec, K., Mizia, M., Janowska, J., Gieszczyk, K., Chmiel, A., Zahorska-Markiewicz, B., and Gasior, Z. N-3 polyunsaturated fatty acids early supplementation improves ultrasound indices of endothelial function, but not through NO inhibitors in patients with acute myocardial infarction: N-3 PUFA supplementation in acute myocardial infarction. Clin.Nutr. 2011;30(1):79-85. View abstract.

Between the ages of five and 65, the majority of the body’s needs can be met by using EPA-rich oils and eating fish, marine products, organic greens and pastured animal products. EPA levels are under constant demand and low EPA levels in adolescents and adults correlates strongly with development of mental health issues, including depression, dyslexia and dyspraxia, heart problems, joint and bone conditions, as well as neurodegenerative diseases such as MS and Parkinson’s. EPA also protects our genes and cell cycle, as well as helping to keep our stress response regulated, so an adequate supply of EPA throughout adult life can help prevent a range of chronic illness.
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).
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
A 2014 meta-analysis of eleven trials conducted respectively on patients with a DSM-defined diagnosis of major depressive disorder (MDD) and of eight trials with patients with depressive symptomatology but no diagnosis of MDD demonstrated significant clinical benefit of omega-3 PUFA treatment compared to placebo. The study concluded that: "The use of omega-3 PUFA is effective in patients with diagnosis of MDD and on depressive patients without diagnosis of MDD."[42]
A, Subgroup meta-analysis of the anxiolytic effect of omega-3 polyunsaturated fatty acids (PUFAs) based on an underlying specific clinical diagnosis or not. The anxiolytic effect of omega-3 PUFAs was not significant in the subgroup of participants without specific clinical conditions (k, 5; Hedges g, –0.008; 95% CI, –0.266 to 0.250; P = .95) but was significant in the subgroup of participants with specific clinical diagnoses (k, 14; Hedges g, 0.512; 95% CI, 0.119-0.906; P = .01). Furthermore, the association of treatment with reduced anxiety symptoms of omega-3 PUFAs were significantly stronger in subgroups with specific clinical diagnoses than in subgroups without specific clinical conditions (P = .03). B, Subgroup meta-analysis of the anxiolytic effect of omega-3 PUFAs based on different mean omega-3 PUFA dosages. The anxiolytic effect of omega-3 PUFAs was not significant in subgroups of mean omega-3 PUFA dosages less than 2000 mg/d (k, 9; Hedges g, 0.457; 95% CI, –0.077 to 0.991; P = .09) but was significant in the subgroup of mean omega-3 PUFA dosage of at least 2000 mg/d (k, 11; Hedges g, 0.213; 95% CI, 0.031-0.395; P = .02).
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.

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.
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.

Hooper, L., Thompson, R. L., Harrison, R. A., Summerbell, C. D., Ness, A. R., Moore, H. J., Worthington, H. V., Durrington, P. N., Higgins, J. P., Capps, N. E., Riemersma, R. A., Ebrahim, S. B., and Davey, Smith G. Risks and benefits of omega 3 fats for mortality, cardiovascular disease, and cancer: systematic review. BMJ 4-1-2006;332(7544):752-760. View abstract.

A 2009 metastudy found that patients taking omega-3 supplements with a higher EPA:DHA ratio experienced fewer depressive symptoms. The studies provided evidence that EPA may be more efficacious than DHA in treating depression. However, this metastudy concluded that due to the identified limitations of the included studies, larger, randomized trials are needed to confirm these findings.[40]

A healthy balance of dietary omega 6 and omega 3 fatty acids is a prerequisite for normal immune function, cognitive health, and cardiovascular health. Among other factors, sufficient dietary levels of EPA, DHA or other omega 3 fatty acids are also important in the regulation of normal blood lipoprotein and healthy cholesterol metabolism. Fish oil supplements can also lower elevated triglyceride levels, improving cardiovascular health and reducing the risk of heart disease.†

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
Omega-3 fats may also impact the development of arthritis. As far back as 1959, studies were published about the effectiveness of cod liver oil on arthritic patients. In the 1959 study, 93 percent of participants “showed major clinical improvement.” (73) While there is no evidence that high omega-3 levels can prevent the development of arthritis, it seems clear that they can reduce inflammation that causes the typical bone and joint pain experienced in the disease. (74)
Krauss-Etschmann, S., Hartl, D., Rzehak, P., Heinrich, J., Shadid, R., Del, Carmen Ramirez-Tortosa, Campoy, C., Pardillo, S., Schendel, D. J., Decsi, T., Demmelmair, H., and Koletzko, B. V. Decreased cord blood IL-4, IL-13, and CCR4 and increased TGF-beta levels after fish oil supplementation of pregnant women. J.Allergy Clin.Immunol. 2008;121(2):464-470. View abstract.
AD is a devastating disease for which there are limited treatment options and no cure. Memory loss is an early indicator of the disease, which is progressive, and leads to the inability of the patient to care for him- or herself and eventually to death (47). Currently, the number of individuals with AD is estimated to be 26.6 million and is expected to increase to 106.2 million by 2050 (48). There have been many studies conducted regarding the use of omega-3 fatty acid supplementation and AD (Table 2). DHA is present in large amounts in neuron membrane phospholipids, where it is involved in proper function of the nervous system, which is why it is thought to play a role in AD (49). A case-control study consisting of 148 patients with cognitive impairment [Mini-Mental State Examination (MMSE) score <24] and 45 control patients (MMSE score ≥24) showed that serum cholesteryl ester-EPA and -DHA levels were significantly lower (P < 0.05 and P < 0.001, respectively) in all MMSE score quartiles of patients with AD compared with control values (49). Another study found that a diet characterized by higher intakes of foods high in omega-3 fatty acids (salad dressing, nuts, fish, tomatoes, poultry, cruciferous vegetables, fruits, dark and green leafy vegetables), and a lower intake of foods low in omega-3 fatty acids (high-fat dairy products, red meat, organ meat, butter) was strongly associated with a lower AD risk (50). Image analysis of brain sections of an aged AD mouse model showed that overall plaque burden was significantly reduced by 40.3% in mice with a diet enriched with DHA (P < 0.05) compared with placebo. The largest reductions (40–50%) were seen in brain regions that are thought to be involved with AD, the hippocampus and parietal cortex (51). A central event in AD is thought to be the activation of multiple inflammatory cells in the brain. Release of IL-1B, IL-6, and TNF α from microglia cells may lead to dysfunction of the neurons in the brain (52). In 1 study, AD patients treated with EPA+DHA supplementation increased their plasma concentrations of EPA and DHA, which were associated with reduced release of inflammatory factors IL-1B, IL-6, and granulocyte colony–stimulating factor from peripheral blood mononuclear cells (53).
Rondanelli, M., Giacosa, A., Opizzi, A., Pelucchi, C., La, Vecchia C., Montorfano, G., Negroni, M., Berra, B., Politi, P., and Rizzo, A. M. Effect of omega-3 fatty acids supplementation on depressive symptoms and on health-related quality of life in the treatment of elderly women with depression: a double-blind, placebo-controlled, randomized clinical trial. J.Am.Coll.Nutr. 2010;29(1):55-64. View abstract.

I now suspect that those thousands of gel-covered capsules I’ve swallowed over the years may have done little more than enrich the pockets of supplement producers and sellers. A number of extensive analyses have been conducted, some supporting and others refuting the value of fish oils to the cardiovascular system, along with studies of other purported health benefits that also have had mixed results.
This fact sheet by the Office of Dietary Supplements (ODS) provides information that should not take the place of medical advice. We encourage you to talk to your healthcare providers (doctor, registered dietitian, pharmacist, etc.) about your interest in, questions about, or use of dietary supplements and what may be best for your overall health. Any mention in this publication of a specific product or service, or recommendation from an organization or professional society, does not represent an endorsement by ODS of that product, service, or expert advice.

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.
In short, there is no single optimal EPA:DHA ratio. If we are really healthy, with an optimal omega-6 to omega-3 ratio (from a diet rich in omega-3 fatty acids and low in grains and vegetable oils) and have an active, stress-free lifestyle, relying on standard fish oil in the natural 1.5:1 EPA:DHA ratio or simply consuming oily fish is completely adequate.

Evidence linking fish oil and cancer has been all over the map. Some research suggests diets high in fatty fish or fish oil supplements might reduce the risk of certain cancers, including prostate cancer. Other research shows just the opposite, a  link between eating a lot of oily fish or taking potent fish oil supplements and a 43% increased risk for prostate cancer overall, and a 71% increased risk for aggressive prostate cancer.
Under these conditions, it may make sense to try fish oil even at higher doses than what I recommended. There is some evidence that krill oil will get the omega-3 fatty acids better into the brain in the psychiatric conditions that I listed. And there is some evidence that EPA-rich fish oils are better than DHA-rich fish oils for some of those psychiatric conditions as well. So there’s room to play around with the different possibilities if those things apply to you. But for the average case, limit the fish oil to 250 milligrams of EPA and DHA combined when you take it, but in all cases, go for food first, and go for fish oil only after you have exhausted those possibilities.
“Lipid peroxidation induced by DHA enrichment modifies paracellular permeability in Caco-2 cells: protective role of taurine.” We conclude that hydrogen peroxide and peroxynitrite may be involved in the DHA-induced increase in paracellular permeability and that the protective role of taurine may be in part related to its capacity to counteract the effects of hydrogen peroxide.

Attention deficit-hyperactivity disorder (ADHD) in children. Early research shows that taking fish oil improves attention, mental function, and behavior in children 8-13 years-old with ADHD. Other research shows that taking a specific supplement containing fish oil and evening primrose oil (Eye Q, Novasel) improves mental function and behavior in children 7-12 years-old with ADHD.