Fish oil


See ((Omega-3 fatty acids))


Fish oil is oil derived from the tissues of oily fish. 


It contains the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), precursors of certain eicosanoids that are known to reduce inflammation in the body and improve hypertriglyceridemia. 


The role of fish oil in cardiovascular disease by  meta-analyses have reached different conclusions about its impact: The most promising evidence supports supplementation for prevention of cardiac death.


Fish sources do not actually produce omega-3 fatty acids, but accumulate them by consuming either microalgae or prey fish that have accumulated omega-3 fatty acids. 


Fatty predatory fish like sharks, swordfish, tilefish, and albacore tuna are high in omega-3 fatty acids but, these species may also accumulate toxic substances through biomagnification.


The EPA  recommends limiting consumption of certain predatory fish species: albacore tuna, shark, king mackerel, tilefish and swordfish, due to high levels of the toxic contaminant mercury. 


Additional toxins in such fish include, dioxins, PCBs, chlordane, as well as other chlorinated cyclodiene insecticides.


Fish that is rich in protein and other vitamins are used as aquaculture feed. 


Of the world’s fish oil used in aquaculture feed, more than 50 percent of it is used in aquaculture feed is fed to farmed salmon.


Marine and freshwater fish oil vary in contents of arachidonic acid, EPA and DHA, ranging  from lean to fatty and their oil content in their tissues ranges from 0.7% to 15.5%.


There is no relation between total fish intake or estimated omega 3 fatty acid intake from all fish, and serum omega3 fatty acid concentrations.


Only fatty fish intake, particularly salmon is the estimated EPA + DHA intake from fatty fish has been observed to be significantly associated with increase in serum EPA + DHA.


There are four fish oil-based approved prescription drugs, namely Lovaza, Omtryg (both omega-3 acid ethyl esters), Vascepa (ethyl eicosapentaenoic acid), and Epanova (omega-3 carboxylic acids).


The most widely available dietary source of EPA and DHA is cold-water oily fish, such as salmon, herring, mackerel, anchovies, and sardines.


Oils from these oily fish have around seven times as much omega-3 oils as omega-6 oils. 


Other oily fish, such as tuna, also contain omega-3 in somewhat lesser amounts. 


Fish do not synthesize omega-3 fatty acids: they obtain them from the algae or plankton in their diets.


Grams of omega-3 fatty acids per 3oz (85g)


Herring, sardines 1.3-2


Spanish mackerel, Atlantic, Pacific 1.1-1.7


Salmon 1.1-1.9


Halibut 0.60-1.12


Tuna 0.21-1.1


Swordfish 0.97


Greenshell/lipped mussels 0.95


Tilefish 0.9


Tuna (canned, light) 0.17-0.24


Pollock 0.45


Cod 0.15-0.24


Catfish 0.22-0.3


Flounder 0.48


Grouper 0.23


Mahi mahi 0.13


Orange roughy 0.028


Red snapper 0.29


Shark 0.83


King mackerel 0.36


Blue eye cod 0.31


Sydney rock oyster 0.30


Tuna, canned 0.23


Snapper 0.22


Barramundi, saltwater 0.100


Giant tiger prawn 0.100


Omega-3 levels in some common non-fish foods:


Grams of omega-3 fatty acids per 3oz (85g) serving of common non-fish foods.


Flaxseeds 19.55


Chia seeds 14.8


Hemp seeds 7.4


Walnut 1.7


Soybean 1.1


Butter 0.27


Eggs, large regular 0.109


Lean red meat


Turkey 0.030


Cereals, rice, pasta, etc. 0.00


Fruit 0.00


Milk, regular 0.00


Bread, regular 0.00


Vegetables 0.0


Recommendations 250-500 mg/day of EPA and DHA.


Recommendation that adults consume at least eight ounces of a variety of types of fish per week, equating to at least 250 mg/day of EPA + DHA.


The Food and Drug Administration recommends not exceeding 3 grams per day of EPA + DHA from all sources, with no more than 2 grams per day from dietary supplements.


The effect of fish oil consumption on prostate cancer is contradictory, with studies suggesting increased or decreased risk.


Controversy exists on role of fish oil in cardiovascular disease: meta-analyses reaching different conclusions about its potential value.


Studies suggest fish oil has little or no reduction in cardiovascular mortality


There appears to be a small reduction in the incidence of actual cardiac events and strokes with its use of fish oils.


The VITAL research group found that fatty acid supplements were not effective in the primary prevention of coronary artery disease and cancer (Manson JE): involved 25,871 healthy individuals without a history of coronary artery disease or pre-existing risk factors for coronary artery disease followed for up to a median and 5.3 years.

In the ASCEND trial there was  significant difference in the risk of vascular events between participants received omega – three supplements compared with those who receives placebo, comparing diabetics and non-diabetics.


The American Heart Association recommends the consumption of 1 gram of fish oil daily, preferably by eating fish, for patients with coronary artery disease, 



Pregnant and nursing women should avoid eating fish with high potential for mercury contaminants including mackerel, shark, and swordfish.


There are three conditions for which fish oil and other omega-3 sources are most highly recommended: 




preventing secondary cardiovascular disease, 




Intake of 3 grams per day or greater of omega-3 fatty acids may increase the risk of bleeding.


Very large intakes of fish oil/omega-3 fatty acids may increase the risk of hemorrhagic stroke.


A meta-analysis published in the Journal of the American Medical Association, covering 20 studies and 68,680 patients, found that Omega-3 Fatty Acid supplementation did not reduce the chance of death, cardiac death, heart attack or stroke.


Another meta-analysis of randomized trials with a total of 77,000 participants published in JAMA found a 3% reduction in the relative risk for those who supplemented fish oil; however, this effect was not statistically significant, but suggested a very minor benefit.


In a Cochrane meta-analysis: total of 79 studies and 112,000 participants and found a 5% reduction in the relative risk for cardiovascular mortality and a 7% reduction in the relative risk for coronary heart disease for those who supplemented with Omega-3s.



Trials that have found  that consuming omega-3 fatty acids slightly reduces blood pressure.


Omega-3 fatty acids can increase the risk of bleeding.


Any benefits of omega-3 fatty acids for depression is inconclusive.


No evidence that omega-3 fatty acid supplements provide a benefit for memory or concentration in later life.


Cod liver oil diet supplementation has been shown beneficial effects on psoriasis.


Studies suggest  better psychomotor development at 30 months of age in infants whose mothers received fish oil supplements for the first four months of lactation.


Five-year-old children whose mothers received docosahexaenoic acid supplementation for the first 4 months of breastfeeding performed better on a test of sustained attention, suggesting 


docosahexaenoic acid intake during early infancy confers long-term benefits on specific aspects of neurodevelopment.


Consumption of fish oil during pregnancy may reduce an infant’s sensitization to common food allergens and reduces the prevalence and severity of certain skin diseases in the first year of life. 


The  consumption of fish oil during pregnancy effects may persist until adolescence with a reduction in prevalence and/or severity of eczema, hay fever and asthma.


Fish oil supplements did not appear to be effective for maintenance of remission in Crohn’s disease.



Problems of quality have been identified in periodic tests by independent researchers of marketed supplements:  contamination, inaccurate listing of EPA and DHA levels, spoilage and formulation issues.



Fish can accumulate toxins such as mercury, dioxins, and polychlorinated biphenyls.



Spoiled fish oil may produce peroxides.



The  concentrations of EPA and DHA in supplements can vary from between 8 and 80% fish oil content. 



EPA and DHA concentration depends on the source of the omega-3s, how the oil is processed, and the amounts of other ingredients included in the supplement.



The bioavailability of EPA and DHA from both capsular and emulsified fish oils has been shown to be high.



Fish oil supplements are available as liquids or capsules. 



Fish oil supplements may be enteric-coated to pass through the stomach before dissolving in the small intestine, thus helping prevent indigestion and burping.



Of enteric-coated products are poorly manufactured they have the potential to release ingredients too early. 



Fish oil products may use other additives techniques to hide the fishy taste. 



The prescription fish oil drugs differ from over-the-counter fish oil supplements.



Prescription fish oil is considered a safe and effective option to reduce triglycerides. 



Prescription fish oil products having DHA raise up the LDL-C levels to reduce triglycerides, like fibrates.



Prescription fish oil pills, capsules and tablets have more omega-3 fatty acids than those which are non-prescription. 



As of 2019, four fish oil-based prescription drugs have been approved for the treatment of hypertriglyceridemia



Epanova (omega-3 carboxylic acids)



Lovaza (omega-3 acid ethyl esters)



Omtryg (omega-3 acid ethyl esters)



Vascepa (ethyl eicosapentaenoic acid) 



Some fish-oil products are approved for parenteral nutrition:



The FDA recommends that consumers do not exceed more than three grams per day of EPA and DHA combined, with no more than 2 grams from a dietary supplement.



A 1000 mg pill typically has only 300 mg of omega-3.



Supplementation of 5 grams of EPA and DHA combined does not pose a safety concern for adults.



The liver and liver products, such as cod liver oil, of fish and many animals (such as seals and whales) contain omega-3, along with active form of vitamin A. 



Oily fish has the potential presence of heavy metals and fat-soluble pollutants like PCBs and dioxins, which are known to accumulate up the food chain. 



The benefits of fish intake generally far outweigh the potential risks.



Negligible amounts of mercury are found in purified fish oil.



Microalgae oil is a vegetarian alternative to fish oil, and has lower risk of pollutant exposure.



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