ODS seeks to strengthen knowledge and understanding of dietary supplements by evaluating scientific information, supporting research, sharing research results, and educating the public. Its resources include publications (such as Dietary Supplements: What You Need to Know), fact sheets on a variety of specific supplement ingredients and products (such as vitamin D and multivitamin/mineral supplements), and the PubMed Dietary Supplement Subset
Good points, Miroslav. Focusing on your 4th point, with so many different formulations on the market that contain various preservatives, only looking at the blood levels of omega-3’s as the flag for increased risk for prostate cancer tends to ignore the fact that certain populations in coastal regions maintain a diet high in omega fish oils and don’t have a marked increase level of prostate cancer, pointing to the fact that another agent may be to blame here.
Maclean, C. H., Mojica, W. A., Morton, S. C., Pencharz, J., Hasenfeld, Garland R., Tu, W., Newberry, S. J., Jungvig, L. K., Grossman, J., Khanna, P., Rhodes, S., and Shekelle, P. Effects of omega-3 fatty acids on lipids and glycemic control in type II diabetes and the metabolic syndrome and on inflammatory bowel disease, rheumatoid arthritis, renal disease, systemic lupus erythematosus, and osteoporosis. Evid.Rep.Technol.Assess.(Summ.) 2004;(89):1-4. View abstract.
Nakamura, N., Hamazaki, T., Ohta, M., Okuda, K., Urakaze, M., Sawazaki, S., Yamazaki, K., Satoh, A., Temaru, R., Ishikura, Y., Takata, M., Kishida, M., and Kobayashi, M. Joint effects of HMG-CoA reductase inhibitors and eicosapentaenoic acids on serum lipid profile and plasma fatty acid concentrations in patients with hyperlipidemia. Int J Clin Lab Res 1999;29(1):22-25. View abstract.
Due to the anticipated heterogeneity, a random-effects meta-analysis was chosen rather than a fixed-effects meta-analysis because random-effects modeling is more stringent and incorporates an among-study variance in the calculations. The entire meta-analysis procedure was performed on the platform of Comprehensive Meta-analysis statistical software, version 3 (Biostat). Under the preliminary assumption that the scales for anxiety symptoms are heterogeneous among the recruited studies, we chose Hedges g and 95% confidence intervals to combine the effect sizes, in accordance with the manual of the Comprehensive Meta-analysis statistical software, version 3. Regarding the interpretation of effect sizes, we defined Hedges g values 0 or higher as a better association of treatment with reduced anxiety symptoms of omega-3 PUFAs than in controls. For each analysis, a 2-tailed P value less than .05 was considered to indicate statistical significance. When more than 1 anxiety scale was used in a study, we chose the one with the most informative data (ie, mean and standard deviation [SD] before and after treatment). We entered the primary outcome provided in the included articles or obtained from the original authors. As for the variance imputation, we mainly chose the mean and SD before and after treatment. Later, we entered the mean and SD and calculated the effect sizes based on the software option, standardized by post score SD. In the case of studies with 2 active treatment arms, we merged the 2 active treatment arms into 1 group. If these 2 active treatment arms belonged to different subgroups (ie, different PUFA dosage subgroups), we kept them separate. Regarding the numbers of participants counted, we chose intention-to-treat as our priority. If there were insufficient data in the intention to treat group (ie, some studies only provided the changes in anxiety severity in those participants completing trials), we chose instead the per-protocol numbers of participants.
The current American diet has changed over time to be high in SFA and low in omega-3 fatty acids (12). This change in eating habits is centered on fast food containing high amounts of saturated fat, which has small amounts of essential omega-3 PUFA compared with food prepared in the home (13). Seafood sources such as fish and fish-oil supplements are the primary contributors of the 2 biologically important dietary omega-3 fatty acids, EPA and DHA (14–16). This low intake of dietary EPA and DHA is thought to be associated with increased inflammatory processes as well as poor fetal development, general cardiovascular health, and risk of the development of Alzheimer's disease (AD).

Krill oil is a source of omega−3 fatty acids.[116] The effect of krill oil, at a lower dose of EPA + DHA (62.8%), was demonstrated to be similar to that of fish oil on blood lipid levels and markers of inflammation in healthy humans.[117] While not an endangered species, krill are a mainstay of the diets of many ocean-based species including whales, causing environmental and scientific concerns about their sustainability.[118][119][120]
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.

Today the only Food and Drug Administration (FDA)-approved form of dietary omega-3 FA supplement is Lovaza (omega-3-acid ethyl esters; GlaxoSmithKline), which contains 375 mg of DHA and 465 mg of EPA per 1 g capsule. The myriad of dietary supplements of fish oil, including Kosher capsules, vary from comparable content to insignificant amounts, and for the most part can include other fats and cholesterols. In comparison, to achieve approximately 1 g of EPA and DHA in a meal, 12 ounces of canned light tuna, 2 to 3 ounces of sardines, 1.5 to 2.5 ounces of farmed Atlantic salmon, or 20 ounces of farmed catfish must be consumed (Table 1).65 Unfortunately, potentially high levels of harmful pollutants offset this source of omega-3 FA. The FDA action level for unacceptably high mercury content in fish is 1.0 μg/g. The mercury level in most fish is at or below 0.1 μg/g, but tilefish, swordfish, and king mackerel have high levels of mercury. The majority of fish species also contain <100 ng/g of polychlorinated biphenyls, which is below the FDA action level of 2000 ng/g. Dioxins, which do not have FDA action levels, are present in the majority of marine life.66

Your body can convert some ALA into EPA and then DHA, but not enough to meet all your body’s needs but the best way to assure you are getting enough heart healthy fats is to eat foods high in the omega 3 fats, and if you can’t or don’t get enough of these necessary fats in your diet, you might consider taking an omega 3 supplement to boost these needed fats. More on this later.
Evidence suggests that omega−3 fatty acids modestly lower blood pressure (systolic and diastolic) in people with hypertension and in people with normal blood pressure.[25] Some evidence suggests that people with certain circulatory problems, such as varicose veins, may benefit from the consumption of EPA and DHA, which may stimulate blood circulation and increase the breakdown of fibrin, a protein involved in blood clotting and scar formation.[26][27] Omega−3 fatty acids reduce blood triglyceride levels but do not significantly change the level of LDL cholesterol or HDL cholesterol in the blood.[28][29] The American Heart Association position (2011) is that borderline elevated triglycerides, defined as 150–199 mg/dL, can be lowered by 0.5-1.0 grams of EPA and DHA per day; high triglycerides 200–499 mg/dL benefit from 1-2 g/day; and >500 mg/dL be treated under a physician's supervision with 2-4 g/day using a prescription product.[30]
Interestingly, the results are also consistent with our recent findings that somatic anxiety is associated with omega-3 PUFA deficits and the genetic risks of PUFA metabolic enzyme cytosolic phospholipase A2 in major depressive disorder62,63 and interferon α–induced neuropsychiatric syndrome.63,64 Brain membranes contain a high proportion of omega-3 PUFAs and their derivatives and most animal and human studies suggest that a lack of omega-3 PUFAs in the brain might induce various behavioral and neuropsychiatric disorders,16,65-70 including anxiety-related behaviors.12,18,19,32,49,71 Emerging evidence suggests that omega-3 PUFAs interfere with and possibly control several neurobiological processes, such as neurotransmitter systems, neuroplasticity, and inflammation,12,72 which is postulated to be the mechanism underlying anxiety and depression.

DHA is vital for early brain development and maintenance, while EPA seems to be closely related to behavior and mood. Together, both molecules provide critical neuroprotective benefits.11 These neuroprotective effects are important for the prevention of age-related brain shrinkage (cortical atrophy). Aging adults with brain shrinkage often experience memory loss, cognitive decline, and an increase in depression.12-14

A Pregnancy Prerequisite: Omega-3 fatty acids directly affect brain development, making it crucial for expectant mothers. Additionally, research indicates they decrease a mother's risk of depression. When the mother doesn't have enough of these essential fatty acids, the baby borrows from her. Some prenatal vitamins now include omega-3s, so be sure to check the label or grab a handful of walnuts each day.

Fish oil therapy is efficacious and safe for patients with severe to moderate hypertriglyceridemia. Combination therapy with HMG-CoA reductase inhibitors is also efficacious and has not been associated with any serious adverse reactions. Fish oil therapy added to fenofibrate in patients with severe hypertriglyceridemia is also effective and safe. Accordingly, it may be a safe and effective adjunct in the pharmacotherapy of the mixed lipid disorder that is frequently encountered in patients with the metabolic syndrome and/or type II diabetes mellitus.
Because of the preliminary state of knowledge on the effects of omega-3 PUFA treatment on anxiety, we decided to include as many studies as possible and not to set further limitations on specific characteristics, such as length of study, diagnosis, omega-3 PUFA dosage, omega-3 PUFA preparation (EPA to DHA ratio), rated anxiety coding scale, or type of control. Therefore, we chose to make the inclusion criteria as broad as possible to avoid missing any potentially eligible studies. The inclusion criteria included clinical trials in humans (randomized or nonrandomized), studies investigating the effects of omega-3 PUFA treatment on anxiety symptoms, and formal published articles in peer-reviewed journals. The clinical trials could be placebo controlled or non–placebo controlled. The target participants could include healthy volunteers, patients with psychiatric illness, and patients with physical illnesses other than psychiatric illnesses. The exclusion criteria included case reports or series, animal studies or review articles, and studies not investigating the effects of omega-3 PUFA treatment on anxiety symptoms. We did not set any language limitation to increase the number of eligible articles. Figure 1 shows the literature search and screening protocol.
To evaluate the potential placebo effect, we made further subgrouping analyses. In the subgroups of studies using placebo controls, the omega-3 PUFAs still revealed a consistent positive anxiolytic association with anxiety symptoms. These phenomena meant that the anxiolytic effect of omega-3 PUFAs is probably not entirely owing to the placebo effect.
Luo, J Rizkalla SW Vidal H Oppert JM Colas C Boussairi A Guerre-Millo M Chapuis AS Chevalier A Durand G Slama G. Moderate intake of n-3 fatty acids for 2 months has no detrimental effect on glucose metabolism and could ameliorate the lipid profile in type 2 diabetic men. Results of a controlled study. Diabetes Care. 1998;21(5):717-724. View abstract.
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.
There’s more good news when it comes to fish oil and eye health, and it’s just not just for diabetic this time. Fish oil has been shown to reverse age-related eye disorders. In March 2014, French researchers evaluated 290 patients with age-related macular degeneration (AMD), and they discovered that dietary oil fish and seafood intake were significantly lower in AMD patients. Due to the high EPA and DHA levels in fish oil, it was concluded that this kind of nutritional intervention could especially benefit those at high risk for neovascular age-related macular degeneration. (24)
Dornstauder, B., Suh, M., Kuny, S., Gaillard, F., MacDonald, I., Michael T. Clandinin, M. T., & Sauvé, Y. (2012, June). Dietary docosahexaenoic acid supplementation prevents age-related functional losses and A2E accumulation in the retina. Investigative Ophthalmology and Visual Science. Retrieved from http://iovs.arvojournals.org/article.aspx?articleid=2188773

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)
Meta-analyses (research that combines and analyzes results of multiple studies) generally suggest that the omega-3s are effective, but the findings are not unanimous because of variability between doses, ratios of EPA to DHA, and other study design issues. The most effective preparations appear to have at least 60% EPA relative to DHA. While DHA is thought to be less effective as an antidepressant, it may have protective effects against suicide. Recent work at Massachusetts General Hospital and Emory University suggests that depressed individuals who are overweight and have elevated inflammatory activity may be particularly good candidates for EPA treatment.
Macchia, A., Levantesi, G., Franzosi, M. G., Geraci, E., Maggioni, A. P., Marfisi, R., Nicolosi, G. L., Schweiger, C., Tavazzi, L., Tognoni, G., Valagussa, F., and Marchioli, R. Left ventricular systolic dysfunction, total mortality, and sudden death in patients with myocardial infarction treated with n-3 polyunsaturated fatty acids. Eur.J.Heart Fail. 2005;7(5):904-909. View abstract.
Giacco, R., Cuomo, V., Vessby, B., Uusitupa, M., Hermansen, K., Meyer, B. J., Riccardi, G., and Rivellese, A. A. Fish oil, insulin sensitivity, insulin secretion and glucose tolerance in healthy people: is there any effect of fish oil supplementation in relation to the type of background diet and habitual dietary intake of n-6 and n-3 fatty acids? Nutr.Metab Cardiovasc.Dis. 2007;17(8):572-580. View abstract.
Fish oil contains two very important omega-3 PUFAs. I’m talking about docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). DHA and EPA are sometimes called the marine omega-3s because they mainly come from fish. Some of the best fish to eat to obtain fish oil from in your diet include wild-caught salmon, herring, white fish, sardines and anchovies.

According to the American Heart Association (AHA), clinical trials have shown that omega-3 is effective in reducing the incidence of cardiovascular diseases (CVD). Fish oil is a great source of omega-3 and therefore, reduces the risk of heart diseases and heart arrhythmias. It also lowers the level of bad cholesterol (LDL) and increases the level of good cholesterol (HDL). Fish oil prevents the accumulation of triglycerides and also reduces the level of excess triglycerides. Preliminary research has shown that fish oil can be used to prevent atherosclerosis in coronary patients. Thus, fish oil is effective in preventing strokes and regular usage of fish oil can help avoid sudden cardiac death. As per the American Heart Association, these preliminary findings still need to be confirmed by a further detailed research.
Omega-3 fatty acids get a fair amount of time in the press and a great deal of respect at this point. But do you know what omega-3s are? What omega-3 benefits could convince you to add more oily fish (or maybe a supplement) to your diet? Are omega-3 foods really that big of a deal when it comes to eating a nutrient-dense diet? Could you be deficient in these fatty acids?
If you get your omega-3 index measured, you’ll know if your current efforts are sufficient. And this knowledge is especially important given that even health-conscious people are not always self-aware. One survey found that in a group of people with omega-3 index levels in the intermediate risk range, some 30% believed they were consuming enough omega-3s (11). One registered dietitian wrote a compelling story about exactly this experience. She discovered she was in the intermediate range, in spite of her intentions to eat enough fish.
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.
A certain kidney disease called IgA nephropathy. Some research shows that long-term but not short-term use of fish oil can slow the loss of kidney function in high-risk patients with IgA nephropathy. Fish oil might have greater effects when taken at higher doses. Also, it might be most effective in people with IgA nephropathy who have higher levels of protein in the urine.