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Fish oil is
oil An oil is any nonpolar chemical substance that is a viscous liquid at ambient temperatures and is both hydrophobic (does not mix with water, literally "water fearing") and lipophilic (mixes with other oils, literally "fat loving"). Oils have a ...
derived from the
tissues Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North America * ''Triphosa dubitata'', a species of geometer mot ...
of
oily fish Oily fish are fish species with oil in soft tissues and in the coelomic cavity around the gut. Their fillets may contain up to 30% oil, although this figure varies both within and between species. Examples of oily fish include small forage fis ...
. Fish oils contain the
omega-3 fatty acid Omega−3 fatty acids, also called Omega-3 oils, ω−3 fatty acids or ''n''−3 fatty acids, are polyunsaturated fatty acids (PUFAs) characterized by the presence of a double bond, three atoms away from the terminal methyl group in their chemic ...
s eicosapentaenoic acid (EPA) and
docosahexaenoic acid Docosahexaenoic acid (DHA) is an omega-3 fatty acid that is a primary structural component of the human brain, cerebral cortex, skin, and retina. In physiological literature, it is given the name 22:6(n-3). It can be synthesized from alpha-linol ...

docosahexaenoic acid
(DHA), precursors of certain
eicosanoid Eicosanoids are signaling molecules made by the enzymatic or non-enzymatic oxidation of arachidonic acid or other polyunsaturated fatty acids (PUFAs) that are, similar to arachidonic acid, 20 carbon units in length. Eicosanoids are a sub-category o ...
s that are known to reduce
inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molecular m ...
in the body and improve
hypertriglyceridemia Hypertriglyceridemia denotes high (''hyper-'') blood levels (''-emia'') of triglycerides, the most abundant fatty molecule in most organisms. Elevated levels of triglycerides are associated with atherosclerosis, even in the absence of hypercholest ...
. There has been a great deal of controversy in recent years about the role of fish oil in
cardiovascular disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, heart ...
, with recent
meta-analyses A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Meta-analysis can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting mea ...
reaching different conclusions about its potential impact. The most promising evidence supports supplementation for prevention of cardiac death. Fish oil and omega-3 fatty acids have also been studied in a wide variety of other conditions such as
clinical depression Major depressive disorder (MDD), also known simply as depression, is a mental disorder characterized by at least two weeks of pervasive low mood. Low self-esteem, loss of interest in normally enjoyable activities, low energy, and pain without a ...
,
anxiety Anxiety is an emotion characterized by an unpleasant state of inner turmoil, often accompanied by nervous behavior such as pacing back and forth, somatic complaints, and rumination. It includes subjectively unpleasant feelings of dread over antic ...
,
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bleedi ...

cancer
, and
macular degeneration Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred or no vision in the center of the visual field. Early on there are often no symptoms. Over time, however, some p ...
, yet their benefit in these conditions has also not been verified. The fish used as sources do not actually produce omega-3 fatty acids, but instead accumulate them by consuming either
microalgae Microalgae or microphytes are microscopic algae invisible to the naked eye. They are phytoplankton typically found in freshwater and marine systems, living in both the water column and sediment. They are unicellular species which exist individual ...
or
prey fish Forage fish, also called prey fish or bait fish, are small pelagic fish which are preyed on by larger predators for food. Predators include other larger fish, seabirds and marine mammals. Typical ocean forage fish feed near the base of the food c ...
that have accumulated
omega-3 fatty acid Omega−3 fatty acids, also called Omega-3 oils, ω−3 fatty acids or ''n''−3 fatty acids, are polyunsaturated fatty acids (PUFAs) characterized by the presence of a double bond, three atoms away from the terminal methyl group in their chemic ...
s. Fatty predatory fish like
shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha ...
s,
swordfish Swordfish (''Xiphias gladius''), also known as broadbills in some countries, are large, highly migratory, predatory fish characterized by a long, flat, pointed bill. They are a popular sport fish of the billfish category, though elusive. Swordfis ...
,
tilefish Tilefishes are mostly small perciform marine fish comprising the family Malacanthidae. They are usually found in sandy areas, especially near coral reefs. Commercial fisheries exist for the largest species, making them important food fish. Howev ...
, and
albacore tuna The albacore (''Thunnus alalunga''), known also as the longfin tuna, is a species of tuna of the order Perciformes. It is found in temperate and tropical waters across the globe in the epipelagic and mesopelagic zones. There are six distinct stoc ...
may be high in omega-3 fatty acids but, due to their position at the top of the
food chain The food chain in ecology is a chain of trophic relations. Food chain can refer to the food system, the complex economic and ecological systems that bring food to consumers. Food chain may also refer to: * Food Chain (''Buffy'' comic), a comic bas ...
, these species may also accumulate
toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substruct ...
substances through
biomagnification Biomagnification, also known as bioamplification or biological magnification, is any concentration of a toxin, such as pesticides, in the tissues of tolerant organisms at successively higher levels in a food chain. This increase can occur as a re ...

biomagnification
. For this reason, the
United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it bega ...
recommends limiting consumption (especially for women of childbearing age) of certain (predatory) fish species (e.g.
albacore tuna The albacore (''Thunnus alalunga''), known also as the longfin tuna, is a species of tuna of the order Perciformes. It is found in temperate and tropical waters across the globe in the epipelagic and mesopelagic zones. There are six distinct stoc ...
,
shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha ...
,
king mackerel The king mackerel (''Scomberomorus cavalla'') or kingfish, is a migratory species of mackerel of the western Atlantic Ocean and Gulf of Mexico. It is an important species to both the commercial and recreational fishing industries. Description The ...

king mackerel
,
tilefish Tilefishes are mostly small perciform marine fish comprising the family Malacanthidae. They are usually found in sandy areas, especially near coral reefs. Commercial fisheries exist for the largest species, making them important food fish. Howev ...
and
swordfish Swordfish (''Xiphias gladius''), also known as broadbills in some countries, are large, highly migratory, predatory fish characterized by a long, flat, pointed bill. They are a popular sport fish of the billfish category, though elusive. Swordfis ...
) due to high levels of the toxic contaminant
mercury Mercury usually refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol 'Hg' * Mercury (mythology), a Roman god Mercury may also refer to: Companies * Mercury (toy manufacture ...
.
Dioxins Dioxin may refer to: *1,2-Dioxin or 1,4-Dioxin, two unsaturated heterocyclic 6-membered rings where two carbon atoms have been replaced by oxygen atoms, giving the molecular formula C4H4O2 *Dibenzo-1,4-dioxin, the parent compound also known as dib ...
,
PCBs A polychlorinated biphenyl (PCB) is an organic chlorine compound with the formula C12H10−''x''Cl''x''. Polychlorinated biphenyls were once widely deployed as dielectric and coolant fluids in electrical apparatus, carbonless copy paper and in h ...
and
chlordane Chlordane, or chlordan, is an organochlorine compound used as a pesticide. It is a white solid. In the United States, chlordane was used for termite-treatment of approximately 30 million homes until it was banned in 1988. Chlordane was banned 10 y ...
, as well as other chlorinated cyclodiene insecticides are also present. Fish is rich in protein and other vitamins
aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the farming of fish, crustaceans, mollusks, aquatic plants, algae, and other organisms. Aquaculture involves cultivating freshwater and saltwater populations under c ...
feed. More than 50 percent of the world's fish oil used in aquaculture feed is fed to
farmed salmon The aquaculture of salmonids is the farming and harvesting of salmonids under controlled conditions for both commercial and recreational purposes. Salmonids (particularly salmon and rainbow trout), along with carp, and tilapia are the three most i ...
. Marine and freshwater fish oil vary in contents of
arachidonic acid Arachidonic acid (AA, sometimes ARA) is a polyunsaturated omega-6 fatty acid 20:4(ω-6), or 20:4(5,8,11,14). It is structurally related to the saturated arachidic acid found in cupuaçu butter. Its name derives from the New Latin word ''arachis' ...
, EPA and DHA. The various species range from lean to fatty and their oil content in the tissues has been shown to vary from 0.7% to 15.5%. They also differ in their effects on organ lipids. Studies have revealed that there is no relation between total fish intake or estimated omega−3 fatty acid intake from all fish, and serum omega−3 fatty acid concentrations. Only fatty fish intake, particularly salmonid, and estimated EPA + DHA intake from fatty fish has been observed to be significantly associated with increase in serum EPA + DHA. As of 2019, the US
Food and Drug Administration The United States Food and Drug Administration (FDA or USFDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food saf ...
has approved four fish oil-based prescription drugs, namely Lovaza, Omtryg (both
omega-3 acid ethyl esters Omega-3 acid ethyl esters are ethyl esters of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) found in fish oil. Together with dietary changes, they are used to treat high blood triglycerides which may reduce the ...
), Vascepa ( ethyl eicosapentaenoic acid), and Epanova ( omega-3 carboxylic acids).


Uses

Often marketed and sold for consumption as part of the diet or in dietary supplements in contemporary societies, fish oils also have found roles in external use, as
emollient White petrolatum Moisturizer or emollient is a cosmetic preparation used for protecting, moisturizing, and lubricating the skin. These functions are normally performed by sebum produced by healthy skin. The word "emollient" is derived from the Latin ...
s or as general
ointment A topical medication is a medication that is applied to a particular place on or in the body. Most often topical administration means application to body surfaces such as the skin or mucous membranes to treat ailments via a large range of classe ...
s as well as in
body art Body art is art made on, with, or consisting of, the human body. The most common forms of body art are tattoos and body piercings. Other types include scarification, branding, subdermal implants, scalpelling, shaping (for example tight-lacing of co ...

body art
, or for alleged insulation against cold temperatures.


Nutritional details

The most widely available dietary source of EPA and DHA is cold-water
oily fish Oily fish are fish species with oil in soft tissues and in the coelomic cavity around the gut. Their fillets may contain up to 30% oil, although this figure varies both within and between species. Examples of oily fish include small forage fis ...
, such as
salmon Salmon is the common name for several species of ray-finned fish in the family Salmonidae. Other fish in the same family include trout, char, grayling, and whitefish. Salmon are native to tributaries of the North Atlantic (genus ''Salmo'') an ...
,
herring Herring are forage fish, mostly belonging to the family Clupeidae. Herring often move in large schools around fishing banks and near the coast, found particularly in shallow, temperate waters of the North Pacific and North Atlantic Oceans, inclu ...

herring
,
mackerel Mackerel is a common name applied to a number of different species of pelagic fish, mostly from the family Scombridae. They are found in both temperate and tropical seas, mostly living along the coast or offshore in the oceanic environment. Ma ...

mackerel
,
anchovies An anchovy is a small, common forage fish of the family Engraulidae. Most species are found in marine waters, but several will enter brackish water, and some in South America are restricted to fresh water. More than 140 species are placed in 17 ...

anchovies
, and
sardine "Sardine" and "pilchard" are common names that refer to various small, oily forage fish in the herring family Clupeidae. The term "sardine" was first used in English during the early 15th century and may come from the Mediterranean island of S ...
s. Oils from these fish have a profile of around seven times as much omega-3 oils as omega-6 oils. Other oily fish, such as
tuna A tuna (also called tunny) is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bulle ...
, also contain omega-3 in somewhat lesser amounts. Although fish is a dietary source of omega-3 oils, fish do not synthesize them; they obtain them from the
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular microa ...
(
microalgae Microalgae or microphytes are microscopic algae invisible to the naked eye. They are phytoplankton typically found in freshwater and marine systems, living in both the water column and sediment. They are unicellular species which exist individual ...
in particular) or
plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucial ...
in their diets. For comparison, note the omega-3 levels in some common non-fish foods:


Health effects


Various recommendations

In a 2009 letter on a pending revision to the Dietary Guidelines for Americans, the American Heart Association recommended 250–500 mg/day of EPA and DHA. The Guidelines were revised again for 2015–2020; included is a 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.


Prostate cancer

The effect of fish oil consumption on
prostate cancer Prostate cancer is cancer of the prostate. The prostate is a gland in the male reproductive system that surrounds the urethra just below the bladder. Most prostate cancers are slow growing. Cancerous cells may spread to other areas of the body, p ...

prostate cancer
is controversial, as one study showed decreased risk with higher blood levels of DPA, whereas another reported increased risk of more aggressive prostate cancer with higher blood levels of combined
EPA The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it bega ...
and
DHA#REDIRECT DHA A Burmese sword usually in the length of two foot. {{R from other capitalisation ...

DHA
. Some evidence indicated an association between high blood levels of omega-3 fatty acids and an increased prostate cancer risk.


Cardiovascular

There has been a great deal of controversy in recent years about the role of fish oil in cardiovascular disease, with recent meta-analyses reaching different conclusions about its potential impact. Multiple evaluations suggest fish oil has little or no reduction in cardiovascular mortality, in distinction to earlier observational data, though there appears to be a small reduction in the incidence of actual cardiac events and strokes with its use. In 2007, the
American Heart Association The American Heart Association (AHA) is a nonprofit organization in the United States that funds cardiovascular medical research, educates consumers on healthy living and fosters appropriate cardiac care in an effort to reduce disability and deaths ...
had recommended the consumption of 1
gram The gram (alternative spelling: gramme; SI unit symbol: g) is a metric system unit of mass. Originally defined as "the absolute weight of a volume of pure water equal to the cube of the hundredth part of a metre cm3], and at the temperature ...
of fish oil daily, preferably by eating fish, for patients with
coronary artery disease Coronary artery disease (CAD), also called coronary heart disease (CHD), ischemic heart disease (IHD), or simply heart disease, involves the reduction of blood flow to the heart muscle due to build-up of plaque (atherosclerosis) in the arteries o ...
, but cautioned pregnant and nursing women to avoid eating fish with high potential for
mercury Mercury usually refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol 'Hg' * Mercury (mythology), a Roman god Mercury may also refer to: Companies * Mercury (toy manufacture ...
contaminants including mackerel, shark, and swordfish. (Optimal dosage was related to body weight.) The US
National Institutes of Health The National Institutes of Health (NIH) () is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late 1880s and is now part of the United States Department of Health an ...
lists three conditions for which fish oil and other omega-3 sources are most highly recommended:
hypertriglyceridemia Hypertriglyceridemia denotes high (''hyper-'') blood levels (''-emia'') of triglycerides, the most abundant fatty molecule in most organisms. Elevated levels of triglycerides are associated with atherosclerosis, even in the absence of hypercholest ...
(high triglyceride level), preventing secondary
cardiovascular disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, heart ...
, and
hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure typically does not cause symptoms. Long-term high blo ...
(high blood pressure). It then lists 27 other conditions for which there is less evidence. It also lists possible safety concerns: "Intake of 3 grams per day or greater of omega-3 fatty acids may increase the risk of bleeding, although there is little evidence of significant bleeding risk at lower doses. Very large intakes of fish oil/omega-3 fatty acids may increase the risk of hemorrhagic (bleeding) stroke." There is also some evidence that fish oil may have a beneficial effect on certain abnormal heart rhythms. However, a 2012
meta-analysis A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Meta-analysis can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting mea ...
found no such significant benefit. A 2008
meta-study A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Meta-analysis can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting mea ...
by the ''
Canadian Medical Association Journal The ''Canadian Medical Association Journal'' (French ''Journal de l'Association Médicale Canadienne'') is a peer-reviewed general medical journal published by the Canadian Medical Association (CMA). It publishes original clinical research, analy ...
'' found fish oil supplementation did not demonstrate any preventative benefit to cardiac patients with
ventricular arrhythmia Arrhythmia, also known as cardiac arrhythmia or heart arrhythmia, is a group of conditions in which the heartbeat is irregular, too fast, or too slow. The heart rate that is too fast – above 100 beats per minute in adults – is called tachyca ...
s. A 2012 meta-analysis published in the
Journal of the American Medical Association ''JAMA: The Journal of the American Medical Association'' is a peer-reviewed medical journal published 48 times a year by the American Medical Association. It publishes original research, reviews, and editorials covering all aspects of biomedicin ...
, 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. A 2018 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 2018, Cochrane conducted their own meta-analysis with a 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.


Hypertension

There have been some human trials that have concluded that consuming omega-3 fatty acids slightly reduces blood pressure (DHA could be more effective than EPA). It is important to note that because omega-3 fatty acids can increase the risk of bleeding, a qualified healthcare provider should be consulted before supplementing with fish oil.


Mental health

A 2008 Cochrane
systematic review Systematic reviews are a type of review that uses repeatable analytical methods to collect secondary data and analyse it. Systematic reviews are a type of evidence synthesis which formulate research questions that are broad or narrow in scope, and ...
found that limited data is available. In the one eligible study, omega-3s were an effective adjunctive therapy for depressed but not manic symptoms in
bipolar disorder Bipolar disorder, previously known as manic depression, is a mental disorder characterized by periods of depression and periods of abnormally elevated mood that last from days to weeks each. If the elevated mood is severe or associated with ps ...
. The authors found an "acute need" for more randomised controlled trials. 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. In a 2011
meta-analysis A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Meta-analysis can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting mea ...
of
PubMed PubMed is a free search engine accessing primarily the MEDLINE database of references and abstracts on life sciences and biomedical topics. The United States National Library of Medicine (NLM) at the National Institutes of Health maintain the da ...
articles about fish oil and depression from 1965 to 2010, researchers found that "nearly all of the treatment efficacy observed in the published literature may be attributable to publication bias." 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."


Alzheimer's disease

A Cochrane
meta-analysis A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Meta-analysis can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting mea ...
published in June 2012 found no significant protective effect for cognitive decline for those aged 60 and over and who started taking fatty acids after this age. A co-author of the study said to ''
Time Time is the indefinite continued progress of existence and events that occur in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence event ...
'', "Our analysis suggests that there is currently no evidence that omega-3 fatty acid supplements provide a benefit for memory or concentration in later life".


Psoriasis

Diets supplemented with
cod liver oil Cod liver oil is a dietary supplement derived from liver of cod fish (Gadidae). As with most fish oils, it contains the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Cod liver oil also contains vitamin A and v ...

cod liver oil
have shown beneficial effects on
psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by raised areas of abnormal skin. These areas are red, or purple on some people with darker skin, dry, itchy, and scaly. Psoriasis varies in severity from small, localiz ...
.


Pregnancy

Some studies reported better psychomotor development at 30 months of age in infants whose mothers received fish oil supplements for the first four months of lactation. In addition, five-year-old children whose mothers received modest algae based docosahexaenoic acid supplementation for the first 4 months of breastfeeding performed better on a test of sustained attention. This suggests that
docosahexaenoic acid Docosahexaenoic acid (DHA) is an omega-3 fatty acid that is a primary structural component of the human brain, cerebral cortex, skin, and retina. In physiological literature, it is given the name 22:6(n-3). It can be synthesized from alpha-linol ...

docosahexaenoic acid
intake during early infancy confers long-term benefits on specific aspects of neurodevelopment. In addition, provision of fish oil during pregnancy may reduce an infant's sensitization to common food allergens and reduce the prevalence and severity of certain skin diseases in the first year of life. This effect may persist until adolescence with a reduction in prevalence and/or severity of eczema, hay fever and asthma.


Crohn's disease

A 2014 Cochrane review found that, based on two large studies, fish oil supplements did not appear to be effective for maintenance of remission in
Crohn's disease Crohn's disease is a type of inflammatory bowel disease (IBD) that may affect any segment of the gastrointestinal tract from the mouth to the anus. Symptoms often include abdominal pain, diarrhea (which may be bloody if inflammation is severe), ...
.


Supplement quality and concerns

Fish oil is a commonly used
dietary supplement A dietary supplement is a manufactured product intended to supplement one's diet by taking a pill, capsule, tablet, powder or liquid. A supplement can provide nutrients either extracted from food sources or that are synthetic in order to ...
, with sales in the U.S. alone reaching $976 million in 2009. Problems of quality have been identified in periodic tests by independent researchers of marketed supplements containing fish oil and other marine oils. These problems include contamination, inaccurate listing of EPA and DHA levels, spoilage and formulation issues.


Contamination

Fish can accumulate toxins such as mercury, dioxins, and
polychlorinated biphenyl A polychlorinated biphenyl (PCB) is an organic chlorine compound with the formula C12H10−''x''Cl''x''. Polychlorinated biphenyls were once widely deployed as dielectric and coolant fluids in electrical apparatus, carbonless copy paper and in h ...
s (PCBs), and spoiled fish oil may produce peroxides. There appears to be little risk of contamination by microorganisms, proteins, lysophospholipids, cholesterol, and trans-fats.


Dioxins and PCBs

Dioxins and PCBs may be carcinogenic at low levels of exposure over time. These substances are identified and measured in one of two categories, dioxin-like PCBs and total PCBs. While the U.S. FDA has not set a limit for PCBs in supplements, the Global Organization for EPA and DHA (GOED) has established a guideline allowing for no more than 3 picograms of dioxin-like PCBs per gram of fish oil. In 2012, samples from 35 fish oil supplements were tested for PCBs. Trace amounts of PCBs were found in all samples, and two samples exceeded the GOED's limit. Although trace amounts of PCBs contribute to overall PCB exposure, Consumerlab.com claims the amounts reported by tests it ordered on fish oil supplements are far below those found in a single typical serving of fish.


Spoilage

Peroxides can be produced when fish oil spoils. A study commissioned by the government of Norway concluded there would be some health concern related to the regular consumption of oxidized ( rancid) fish/marine oils, particularly in regards to the gastrointestinal tract, but there is not enough data to determine the risk. The amount of spoilage and contamination in a supplement depends on the raw materials and processes of extraction, refining, concentration, encapsulation, storage and transportation. ConsumerLab.com reports in its review that it found spoilage in test reports it ordered on some fish oil supplement products.


EPA and DHA content

According to ConsumerLab.com tests, the concentrations of EPA and DHA in supplements can vary from between 8 and 80% fish oil content. The concentration depends on the source of the omega-3s, how the oil is processed, and the amounts of other ingredients included in the supplement. A 2012 report claims 4 of 35 fish oil supplements it covered contained less EPA or DHA than was claimed on the label, and 3 of 35 contained more. A ConsumerLab.com publication in 2010 claims 3 of 24 fish oil supplements it covered contained less EPA and/or DHA than was claimed on the label. However, the bioavailability of EPA and DHA from both capsular and emulsified fish oils has been shown to be high.


Formulation

Fish oil supplements are available as liquids or capsules. Some capsules are enteric-coated to pass through the stomach before dissolving in the small intestine, thus helping prevent indigestion and "fish burps". Poorly manufactured enteric-coated products have the potential to release ingredients too early. ConsumerLab.com, a for-profit supplement testing company, reported that 1 of the 24 enteric-coated fish oil supplements it evaluated released ingredients prematurely. Fish oil products may use other techniques to hide the fishy taste. For example, added lemon or strawberry
flavor Flavor (American English), flavour (British English; see spelling differences), or taste is the perceptual impression of food or other substances, and is determined primarily by the chemical senses of the gustatory and olfactory system. The "trig ...
tends to produce a more agreeable product.


Prescription fish oil

Fish oil preparations that are only available with a doctor's prescription undergo the same US
Food and Drug Administration The United States Food and Drug Administration (FDA or USFDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food saf ...
(FDA) regulatory requirements as other prescription pharmaceuticals, with regard to both efficacy and safety. The prescription fish oil drugs differ from over-the-counter fish oil supplements. They should not be confused with each other. Prescription fish oil is considered a safe and effective option to reduce
triglyceride 300px, Example of an unsaturated fat triglyceride (C55H98O6). Left part: glycerol; right part, from top to bottom: palmitic acid, oleic acid, alpha-linolenic acid. A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester de ...
s. There are various prescription fish oil products that have been approved and permitted by the FDA for increasing triglyceride levels. Prescription fish oil products having DHA raise up the LDL-C levels to reduce triglycerides, like
fibrate In pharmacology, the fibrates are a class of amphipathic carboxylic acids. They are used for a range of metabolic disorders, mainly hypercholesterolemia (high cholesterol), and are therefore hypolipidemic agents. Medical uses Fibrates are used in ...
s. Heart experts advise that prescription fish oil helps in decreasing additional levels of blood fats. Prescription fish oils might only help when triglycerides reach a specific upper level. Prescription fish oil pills, capsules and tablets have more omega-3 fatty acids than those which are non-prescription. The FDA regularly monitors prescription fish oil for standards, quality and safety. As of 2019, four fish oil-based prescription drugs have been approved in the United States for the treatment of hypertriglyceridemia, namely: #Epanova (omega-3 carboxylic acids) was approved on 23 April 2014. Clinical trial on mixed dyslipidaemia (hypertriglyceridemia with hypocholesterolemia) started in 2014 found that it has no medical benefits, and the clinical trial was called off on 13 January 2019. #Lovaza (omega-3 acid ethyl esters) was approved on 10 November 2004. #Omtryg (omega-3 acid ethyl esters) was approved on 23 April 2014. #Vascepa (ethyl eicosapentaenoic acid) was approved on 26 July 2012. On 13 December 2019, the FDA also approved it as the first drug specifically "to reduce cardiovascular risk among patients with elevated triglyceride levels." Some fish-oil products are approved for
parenteral nutrition Parenteral nutrition (PN) is the feeding of nutritional products to a person intravenously, bypassing the usual process of eating and digestion. The products are made by pharmaceutical compounding companies. The person receives a nutritional form ...
: #
Omegaven Fish oil, sold under the brand name Omegaven, is a fatty acid emulsion. It is used for total parenteral nutrition (feeding directly into a venous catheter), e.g. in short bowel syndrome. It is rich in omega-3 fatty acids. It has gained popularity ...
, approved in July 2018, is indicated as a source of calories and fatty acids in children with parenteral nutrition-associated cholestasis (PNAC). #Smoflipid, approved in July 2016, is indicated in adults as a source of calories and essential fatty acids for parenteral nutrition when oral or enteral nutrition is not possible, insufficient, or contraindicated.


Dangers

A 2013 review concluded that the potential for adverse events amongst older adults taking fish oil "appear mild–moderate at worst and are unlikely to be of clinical significance".


Maximum intake

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. This is not the same as 3000 mg of fish oil. A 1000 mg pill typically has only 300 mg of omega-3; 10 such pills would equal 3000 mg of omega-3. According to the
European Food Safety Authority The European Food Safety Authority (EFSA) is the agency of the European Union (EU) that provides independent scientific advice and communicates on existing and emerging risks associated with the food chain. EFSA was established in February 2002, is ...
's (EFSA) Panel on Dietetic Products, Nutrition and Allergies, supplementation of 5 grams of EPA and DHA combined does not pose a safety concern for adults. A 1987 study found that healthy
Greenlandic Inuit Greenlanders ( kl, Kalaallit / Tunumiit / Inughuit; da, Grønlændere) are people identified with the country of Greenland or the indigenous people, the Greenlandic Inuit (kalaallit, inughuit or tunumiit). This connection may be residential, lega ...
had an average intake of 5.7 grams of omega-3 EPA per day which had many effects including prolonged bleeding times, such as slower
blood clotting Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanism o ...
.


Vitamins

The liver and liver products (such as
cod liver oil Cod liver oil is a dietary supplement derived from liver of cod fish (Gadidae). As with most fish oils, it contains the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Cod liver oil also contains vitamin A and v ...

cod liver oil
) of fish and many animals (such as seals and whales) contain omega-3, but also the active form of
vitamin A Vitamin A is a group of unsaturated nutritional organic compounds that includes retinol, retinal, and several provitamin A carotenoids (most notably beta-carotene). Vitamin A has multiple functions: it is important for growth and development, f ...

vitamin A
. At high levels, this form of the vitamin can be dangerous (
Hypervitaminosis A Hypervitaminosis A refers to the toxic effects of ingesting too much preformed vitamin A (retinyl esters, retinol, and retinal). Symptoms arise as a result of altered bone metabolism and altered metabolism of other fat-soluble vitamins. Hypervitamin ...
).


Toxic pollutants

Consumers of oily fish should be aware of the potential presence of
heavy metals Heavy metals are generally defined as metals with relatively high densities, atomic weights, or atomic numbers. The criteria used, and whether metalloids are included, vary depending on the author and context. In metallurgy, for example, a hea ...
and fat-soluble pollutants like
PCBs A polychlorinated biphenyl (PCB) is an organic chlorine compound with the formula C12H10−''x''Cl''x''. Polychlorinated biphenyls were once widely deployed as dielectric and coolant fluids in electrical apparatus, carbonless copy paper and in h ...
and
dioxins Dioxin may refer to: *1,2-Dioxin or 1,4-Dioxin, two unsaturated heterocyclic 6-membered rings where two carbon atoms have been replaced by oxygen atoms, giving the molecular formula C4H4O2 *Dibenzo-1,4-dioxin, the parent compound also known as dib ...
, which are known to . After extensive review, researchers from Harvard's School of Public Health in the ''Journal of the American Medical Association'' (2006) reported that the benefits of fish intake generally far outweigh the potential risks. Fish oil supplements came under scrutiny in 2006, when the
Food Standards Agency , type = Non-ministerial government department , nativename = , nativename_a = , nativename_r = , logo = Food Standards Agency.svg , logo_width = , logo_caption = , seal = , seal_width = , seal_caption = , picture = , picture_width = , picture_captio ...
in the UK and the
Food Safety Authority of Ireland __NOTOC__ The Food Safety Authority of Ireland (FSAI) ( ga, Údarás Sábháilteachta Bia na hÉireann – USBE) is the statutory body responsible for ensuring food produced, distributed or marketed in Ireland complies with food safety and hygiene st ...
reported PCB levels that exceeded the European maximum limits in several fish oil brands, 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. A March 2010 lawsuit filed by a California environmental group claimed that eight brands of fish oil supplements contained excessive levels of PCB's, including
CVS/pharmacy CVS Pharmacy (stylized as CVSpharmacy, previously CVS/pharmacy) is an American retail corporation. Owned by CVS Health, it is headquartered in Woonsocket, Rhode Island. It was also known as, and originally named, the Consumer Value Store and was ...
, Nature Made,
Rite Aid Rite Aid Corporation is an American drugstore chain based in Camp Hill, Pennsylvania. It was founded in 1962 in Scranton, Pennsylvania by Alex Grass under the name Thrif D Discount Center. The company ranked No. 150 in the 2020 Fortune 500 list of ...

Rite Aid
, GNC, Solgar,
Twinlab Twinlab Consolidated Corporation is an American company which manufactures and markets vitamins, minerals, and bodybuilding supplements. Twinlab is based in Boca Raton, Florida. Twinlab currently produces more than 500 different products.
, Now Health, Omega Protein and Pharmavite. The majority of these products were either cod liver or shark liver oils. Those participating in the lawsuit claim that because the liver is the major filtering and detoxifying organ, PCB content may be higher in liver-based oils than in fish oil produced from the processing of whole fish. 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." A report by the
Harvard Medical School Harvard Medical School (HMS) is the graduate medical school of Harvard University and is located in the Longwood Medical Area of Boston, Massachusetts. Founded in 1782, HMS is one of the oldest medical schools in the United States and is consiste ...
studied five popular brands of fish oil, including Nordic Ultimate, Kirkland and CVS. They found that the brands had "negligible amounts of mercury, suggesting either that mercury is removed during the manufacturing of purified fish oil or that the fish sources used in these commercial preparations are relatively mercury-free".
Microalgae Microalgae or microphytes are microscopic algae invisible to the naked eye. They are phytoplankton typically found in freshwater and marine systems, living in both the water column and sediment. They are unicellular species which exist individual ...
oil is a
vegetarian Vegetarianism is the practice of abstaining from the consumption of meat (red meat, poultry, seafood, and the flesh of any other animal), and may also include abstention from by-products of animal slaughter. Vegetarianism may be adopted for va ...
alternative to fish oil. Supplements produced from microalgae oil provide a balance of omega-3 fatty acids similar to fish oil, with a lower risk of pollutant exposure.


See also

*
Algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular microa ...
*
Cod liver oil Cod liver oil is a dietary supplement derived from liver of cod fish (Gadidae). As with most fish oils, it contains the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Cod liver oil also contains vitamin A and v ...

Cod liver oil
*
Docosahexaenoic acid Docosahexaenoic acid (DHA) is an omega-3 fatty acid that is a primary structural component of the human brain, cerebral cortex, skin, and retina. In physiological literature, it is given the name 22:6(n-3). It can be synthesized from alpha-linol ...

Docosahexaenoic acid
* Eicosapentaenoic acid *
Krill oil Krill oil is an extract prepared from a species of Antarctic krill, ''Euphausia superba''. Two of the most important components in krill oil are omega-3 fatty acids similar to those in fish oil, and phospholipid-derived fatty acids (PLFA), mainly ph ...
* Lovaza *
Shark liver oil Shark liver oil is an oil obtained from the livers of sharks. It has been used for centuries as a folk remedy to promote the healing of wounds and as a remedy for respiratory tract and digestive system problems.


References


Further reading

* FAO (1986
''The production of fish meal and oil''
FAO Fishery Technical Paper 142. .


External links


International Fish Oil Standards
— An
organization An organization, or organisation (Commonwealth English; see spelling differences), is an entity – such as a company, an institution, or an association – comprising one or more people and having a particular purpose. The word is derived ...
concerned with the
quality Quality may refer to: Concepts *Quality (business), the ''non-inferiority'' or ''superiority'' of something *Quality (philosophy), an attribute or a property *Quality (physics), in response theory *Energy quality, used in various science disciplin ...
of omega-3 products as it relates to the
international standard are technical standards developed by international organizations (intergovernmental organizations), such as Codex Alimentarius in food, the World Health Organization Guidelines in health, or ITU Recommendations in ICT and being publicly funded, are ...
s established by the
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution, which establishes the agency's governing structure and principles, states its main objective as ...
and the Council For Responsible Nutrition for purity and concentration. * Two newsletters, both quarterly, reviewing recent publications in essential fatty acids. One is written for researchers, the second is for consumers. Industry sponsored, academic contributors.
Omega-3 Fatty Acids
''American Cancer Society''. Updated 11 January 2008. {{DEFAULTSORT:Fish Oil Dietary supplements Fish products Animal fats