Oily fish

Last updated

The large open-water Atlantic bluefin tuna is an oily fish. Bluefin-big.jpg
The large open-water Atlantic bluefin tuna is an oily fish.
Most small forage fish, like these schooling anchovies, are also oily fish. Anchovy closeup.jpg
Most small forage fish, like these schooling anchovies, are also oily fish.

Oily fish are fish species with oil (fats) 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 fish such as sardines, herring and anchovies, and other larger pelagic fish such as salmon, trout, tuna, swordfish and mackerel. [1]

Contents

Oily fish can be contrasted with whitefish, which contain oil only in the liver and in much less overall quantity than oily fish. Examples of whitefish are cod, haddock and flatfish. White fish are usually demersal fish which live on or near the seafloor, whereas oily fish are pelagic, living in the water column away from the bottom.

Oily fish meat is a good source of important fat-soluble vitamins such as Vitamin A and D, and is rich in omega-3 fatty acids (white fish also contain these nutrients but at a much lower concentration). For this reason the consumption of oily fish rather than white fish can be more beneficial to humans, particularly concerning heart diseases such as stroke and ischemic heart disease; [2] however, oily fish are known to carry higher levels of contaminants (such as mercury or dioxin or POPs) than whitefish.[ citation needed ] Among other benefits, studies suggest that the omega-3 fatty acids in oily fish may help improve inflammatory conditions such as arthritis. [3]

Health benefits

Oily fish fillet (salmon - bottom) contrasted with a white fish fillet (halibut - top) Halibut and salmon fillets.jpg
Oily fish fillet (salmon – bottom) contrasted with a white fish fillet (halibut – top)

Dementia

A 1997 study published in Annals of Neurology followed 5,386 elderly participants in Rotterdam. It found that fish consumption decreased the risk of dementia. [4] However, the 2.1-year average follow-up was less than the three years dementia commonly affects people prior to diagnosis. Thus, the study was unclear as to whether fish consumption protected against dementia, or if dementia prevented the participants from wanting more fish. [5]

French research published in 2002 in the British Medical Journal (BMJ) followed 1,674 elderly residents of southern France for seven years, studying their consumption of meat versus seafood and the presence of dementia symptoms. The conclusion was that people who ate fish at least once a week had a significantly lower risk of being diagnosed with dementia over a seven-year period. This study reinforced the Annals of Neurology findings. Because of the longer term, the BMJ study provided stronger evidence of a genuine protective effect. [5] There was a possible confounding factor in that individuals with higher education have both a lower risk of dementia and higher consumption of fish. [6]

Cardiovascular health

Consuming 200–400 g of oily fish twice per week may also help prevent sudden death due to myocardial infarction by preventing cardiac arrhythmia. [7] The eicosapentaenoic acid found in fish oils appears to dramatically reduce inflammation through conversion within the body to resolvins, with beneficial effects for the cardiovascular system and arthritis. [8]

Grilled salmon, an oily fish Thyme and Garlic Grilled Salmon with Mango Salsa, Rosemary Potatoes and Snow Peas (297986190).jpg
Grilled salmon, an oily fish

In 1994, the UK Committee on Medical Aspects of Food and Nutrition Policy recommended that people eat at least two portions of fish per week, one of which should be oily fish.

In 2004 the UK Food Standards Agency published advice on the recommended minimum and maximum quantities of oily fish to be eaten per week, to balance the beneficial qualities of the omega-3 fatty acids against the potential dangers of ingesting polychlorinated biphenyls and dioxins. It reiterated the 1994 guideline of two portions of fish per week including one portion of oily fish, but advised eating no more than four portions per week, and no more than two portions for people who are pregnant, may become pregnant or who are breastfeeding. [9]

The United States Environmental Protection Agency's (EPA) Exposure Reference Dose (RfI) for methylmercury (MeHg) is 0.1 micrograms per kg body weight per day. The corresponding limit of blood mercury is 5.8 micrograms per liter. The restrictions apply to certain oily fish – "marlin, swordfish, shark and, to a lesser extent, tuna". [10] The recommendations on maximum consumption of oily fish were up to four portions (1 portion = 140g, or approx 4.9 ounces) a week for men, boys, and women past childbearing age, and up to two portions a week for women of childbearing age, including pregnant and breastfeeding women, and girls. There is no recommended limit on the consumption of white fish.

The EPA and 2007 U.S. Department of Agriculture guidelines sets a limit only on consumption of fatty fish with greater than one part per million of methylmercury, specifically tilefish, king mackerel, shark and swordfish. [ citation needed ] There are limits, however, for nursing/pregnant women and children under the age of six. This population should completely avoid fish with high risk of mercury contamination (those listed above) and limit consumption of moderate and low-mercury fish to 12 ounces or less per week. [ citation needed ] Albacore tuna should be limited to six ounces or less per week. [ citation needed ]

Omega-3 content

Concerns about contamination, diet or supply have led to investigation of plant sources of omega-3 fatty acids, notably flax, hempseed and perilla oils. Lactating women who supplemented their diet with flaxseed oil showed increases in blood and breastmilk concentration of alpha-linolenic acid and eicosapentaenoic acid but no changes to concentrations of docosahexaenoic acid. [11]

See also

Related Research Articles

<span class="mw-page-title-main">Fat</span> Esters of fatty acid or triglycerides

In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.

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 chemical structure. They are widely distributed in nature, being important constituents of animal lipid metabolism, and they play an important role in the human diet and in human physiology. The three types of omega−3 fatty acids involved in human physiology are α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA can be found in plants, while DHA and EPA are found in algae and fish. Marine algae and phytoplankton are primary sources of omega−3 fatty acids. DHA and EPA accumulate in fish that eat these algae. Common sources of plant oils containing ALA include walnuts, edible seeds, and flaxseeds as well as hempseed oil, while sources of EPA and DHA include fish and fish oils, and algae oil.

<span class="mw-page-title-main">Seafood</span> Food from the sea

Seafood is any form of sea life regarded as food by humans, prominently including fish and shellfish. Shellfish include various species of molluscs, crustaceans, and echinoderms. Historically, marine mammals such as cetaceans as well as seals have been eaten as food, though that happens to a lesser extent in modern times. Edible sea plants such as some seaweeds and microalgae are widely eaten as sea vegetables around the world, especially in Asia.

Essential fatty acids, or EFAs, are fatty acids that humans and other animals must ingest because the body requires them for good health, but cannot synthesize them.

α-Linolenic acid Chemical compound

α-Linolenic acid, also known as alpha-Linolenic acid (ALA), is an n−3, or omega-3, essential fatty acid. ALA is found in many seeds and oils, including flaxseed, walnuts, chia, hemp, and many common vegetable oils.

<span class="mw-page-title-main">Cod liver oil</span> Dietary supplement derived from liver of cod fish

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), and also vitamin A and vitamin D. Historically, it was given to children because vitamin D had been shown to prevent rickets, a consequence of vitamin D deficiency.

A saturated fat is a type of fat in which the fatty acid chains have all single bonds. A fat known as a glyceride is made of two kinds of smaller molecules: a short glycerol backbone and fatty acids that each contain a long linear or branched chain of carbon (C) atoms. Along the chain, some carbon atoms are linked by single bonds (-C-C-) and others are linked by double bonds (-C=C-). A double bond along the carbon chain can react with a pair of hydrogen atoms to change into a single -C-C- bond, with each H atom now bonded to one of the two C atoms. Glyceride fats without any carbon chain double bonds are called saturated because they are "saturated with" hydrogen atoms, having no double bonds available to react with more hydrogen.

<span class="mw-page-title-main">Omega-6 fatty acid</span> Fatty acids where the sixth bond is double

Omega-6 fatty acids are a family of polyunsaturated fatty acids that have in common a final carbon-carbon double bond in the n-6 position, that is, the sixth bond, counting from the methyl end.

<span class="mw-page-title-main">Fish oil</span> Oil derived from the tissues of oily fish

Fish oil is oil derived from the tissues of oily fish. Fish oils contain 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. There has been a great deal of controversy in the 21st century about the role of fish oil in cardiovascular disease, with recent meta-analyses reaching different conclusions about its potential impact.

<span class="mw-page-title-main">Eicosapentaenoic acid</span> Chemical compound

Eicosapentaenoic acid is an omega-3 fatty acid. In physiological literature, it is given the name 20:5(n-3). It also has the trivial name timnodonic acid. In chemical structure, EPA is a carboxylic acid with a 20-carbon chain and five cis double bonds; the first double bond is located at the third carbon from the omega end.

<span class="mw-page-title-main">Docosahexaenoic acid</span> Chemical compound

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-linolenic acid or obtained directly from maternal milk, fatty fish, fish oil, or algae oil.

<span class="mw-page-title-main">Fish as food</span> Fish eaten by humans

Many species of fish are caught by humans and consumed as food in virtually all regions around the world. Fish has been an important dietary source of protein and other nutrients throughout human history.

<span class="mw-page-title-main">Nutrition and pregnancy</span> Nutrient intake and dietary planning undertaken before, during and after pregnancy

Nutrition and pregnancy refers to the nutrient intake, and dietary planning that is undertaken before, during and after pregnancy. Nutrition of the fetus begins at conception. For this reason, the nutrition of the mother is important from before conception as well as throughout pregnancy and breastfeeding. An ever-increasing number of studies have shown that the nutrition of the mother will have an effect on the child, up to and including the risk for cancer, cardiovascular disease, hypertension and diabetes throughout life.

<span class="mw-page-title-main">Polyunsaturated fat</span> Type of fatty acid defined by molecular bonds

In biochemistry and nutrition, a polyunsaturated fat is a fat that contains a polyunsaturated fatty acid, which is a subclass of fatty acid characterized by a backbone with two or more carbon–carbon double bonds. Some polyunsaturated fatty acids are essentials. Polyunsaturated fatty acids are precursors to and are derived from polyunsaturated fats, which include drying oils.

Docosapentaenoic acid (DPA) designates any straight open chain polyunsaturated fatty acid (PUFA) which contains 22 carbons and 5 double bonds. DPA is primarily used to designate two isomers, all-cis-4,7,10,13,16-docosapentaenoic acid and all-cis-7,10,13,16,19-docosapentaenoic acid. They are also commonly termed n-6 DPA and n-3 DPA, respectively; these designations describe the position of the double bond being 6 or 3 carbons closest to the (omega) carbon at the methyl end of the molecule and is based on the biologically important difference that n-6 and n-3 PUFA are separate PUFA classes, i.e. the omega-6 fatty acids and omega-3 fatty acids, respectively. Mammals, including humans, can not interconvert these two classes and therefore must obtain dietary essential PUFA fatty acids from both classes in order to maintain normal health.

Fish oil, sold under the brand name Omegaven, is a fatty acid emulsion. It is used for total parenteral nutrition, e.g. in short bowel syndrome. It is rich in omega-3 fatty acids.

<span class="mw-page-title-main">Mercury in fish</span>

The presence of mercury in fish is a health concern for people who eat them, especially for women who are or may become pregnant, nursing mothers, and young children. Fish and shellfish concentrate mercury in their bodies, often in the form of methylmercury, a highly toxic organomercury compound. This element is known to bioaccumulate in humans, so bioaccumulation in seafood carries over into human populations, where it can result in mercury poisoning. Mercury is dangerous to both natural ecosystems and humans because it is a metal known to be highly toxic, especially due to its neurotoxic ability to damage the central nervous system.

Only two essential fatty acids are known to be essential for humans: alpha-linolenic acid and linoleic acid. The biological effects of the ω-3 and ω-6 fatty acids are mediated by their mutual interactions. Closely related, these fatty acids act as competing substrates for the same enzymes. The biological effects of the ω-3 and ω-6 fatty acids are largely mediated by essential fatty acid interactions. The proportion of omega-3 to omega-6 fatty acids in a diet may have metabolic consequences. Unlike omega-3 fatty acids and omega-6 fatty acids, omega-9 fatty acids are not classed as essential fatty acids because they can be created by the human body from monounsaturated and saturated fatty acids, and are therefore not essential in the diet.

Omega-3 carboxylic acids (Epanova) is a formerly marketed yet still not an Food And Drug Administration (FDA) approved prescription medication–since taken off market by the manufacturer–used alongside a low fat and low cholesterol diet that lowers high triglyceride (fat) levels in adults with very high levels. This was the third class of fish oil-based drug, after omega-3 acid ethyl esters and ethyl eicosapentaenoic acid (Vascepa), to be approved for use as a drug. The first approval by US Food and Drug Administration was granted 05 May 2014. These fish oil drugs are similar to fish oil dietary supplements, but the ingredients are better controlled and have been tested in clinical trials. Specifically, Epanova contained at least 850 mg omega-3-acid ethyl esters per 1 g capsule.

<span class="mw-page-title-main">Trans fat</span> Type of unsaturated fat

Trans fat, also called trans-unsaturated fatty acids, or trans fatty acids, is a type of unsaturated fat that occurs in foods. Trace concentrations of trans fats occur naturally, but large amounts are found in some processed foods. Since consumption of trans fats is unhealthy, artificial trans fats are highly regulated or banned in many nations. However, they are still widely consumed in developing nations, resulting in hundreds of thousands of deaths each year. The World Health Organization (WHO) has set a goal to make the world free from industrially produced trans fat by the end of 2023.

References

  1. ↑ "What's an oily fish?". Food Standards Agency. 24 June 2004. Archived from the original on 10 December 2010.
  2. ↑ "Oily fish helps heart attack victims to live longer - 07 October 1989". New Scientist. 7 October 1989. Retrieved 27 July 2009.
  3. ↑ Kremer JM (2017). "Fish Oil and Inflammation — A Fresh Look". The Journal of Rheumatology. 44 (6): 713–716. doi: 10.3899/jrheum.161551 . PMID   28572471.
  4. ↑ Kalmijn, S.; Launer, L. J.; Ott, A.; Witteman, J. C. M.; Hofman, A.; Breteler, M. M. B. (1997). "Dietary fat intake and the risk of incident dementia in the Rotterdam study". Annals of Neurology. 42 (5): 776–782. doi:10.1002/ana.410420514. hdl: 1765/58975 . PMID   9392577. S2CID   24435633.
  5. 1 2 Barberger-Gateau, P.; Letenneur, L.; Deschamps, V.; Pérès, K.; Dartigues, J. F.; Renaud, S. (2002). "Fish, meat, and risk of dementia: Cohort study". BMJ (Clinical Research Ed.). 325 (7370): 932–933. doi:10.1136/bmj.325.7370.932. PMC   130057 . PMID   12399342.
  6. ↑ Wilkinson, Emma (9 March 2009). "Oily fish dementia boosts queried". BBC News. Retrieved 27 July 2009.
  7. ↑ Leaf, A.; Kang, J. X.; Xiao, Y.-F.; Billman, G. E. (2003). "Clinical prevention of sudden cardiac death by n-3 polyunsaturated fatty acids and mechanism of prevention of arrhythmias by n-3 fish oils". Circulation. 107 (21): 2646–52. doi: 10.1161/01.CIR.0000069566.78305.33 . PMID   12782616.
  8. ↑ Arita, M.; Bianchini F; Aliberti J; Sher A; Chiang N; Hong S; Yang R; Petasis NA; Serhan CN (2005). "Stereochemical assignment, antiinflammatory properties, and receptor for the Omega-3 lipid mediator Resolvin E1". Journal of Experimental Medicine . 201 (5): 713–22. doi:10.1084/jem.20042031. PMC   2212834 . PMID   15753205. Open Access logo PLoS transparent.svg
  9. ↑ "Oily fish advice: your questions answered". Food Standards Agency. 23 June 2004. Archived from the original on 3 December 2013. Retrieved 17 February 2014.
  10. ↑ SACN (2004) Advice on fish consumption: benefits and risks, 20 May 2014, Committee on Toxicity. ISBN   011243083X.
  11. ↑ Francois, C.A.; Connor, S. L.; Bolewicz, L. C.; Connor, W. E. (1 January 2003). "Supplementing lactating women with flaxseed oil does not increase docosahexaenoic acid in their milk". American Journal of Clinical Nutrition. 77 (1): 226–233. doi: 10.1093/ajcn/77.1.226 . PMID   12499346 . Retrieved 21 November 2022.

Further reading

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.