Eicosapentaenoic acid - EPA

Jan 2014  Eicosapentaenoic acid (EPA)
Eicosapentaenoic acid is a long-chain polyunsaturated 20-carbon omega-3 fatty acid. In humans, eicosapentaenoic acid (EPA), is not an essential fat, as in the human body it can be synthesized from dietary alpha-linolenic acid or ALA 18:3(n−3).
However EPA (20:5, n−3) is essential for many biochemical and metabolic functions in the body. In the absence of sufficient dietary ALA or in an inability to synthesize eicosapentaenoic acid from ALA, dietary source of EPA becomes essential for the body to carry on its biochemical processes.

Structure of eicosapentaenoic acid (EPA)

EPA is an organic carboxylic acid characterized by the presence of carboxyl group. It has 20-carbon chain and five cis double bonds; the first double bond is located at the third carbon from the omega end.

Its trivial name is timnodonicacid. Its IUPAC name is (5Z,8Z,11Z,14Z,17Z)-5,8,11,14,17-icosapentaenoic acid.
Its molecular formula is C20H30O2.
The chemical structure of 20:5(n−3) is:

Eicosapentaenoic acid food sources and synthesis

EPA is found in abundance in fish oils and oily fish such as salmon, herring, mackerel, anchovies, and sardines. Although the fish oil contains EPA, the fish do not synthesize it. They obtain it from their dietary sources like plankton, algae, sea weed, krill and microalgae. Fish oil is the primary source of EPA and also DHA. Supplements of these fatty acids are available in the form of fish oil capsules.

EPA can be obtained from non-animal sources like marine algae for human consumption and in fact it is commercially produced from microalgae. It is not found in terrestrial plants. In plants like purslane (Portulaca oleracea) EPA is found in trace amounts. Consuming foods rich in ALA like canola oil and linseed can increase the ALA levels and lead to increased synthesis of EPA.

Human body can convert ALA to EPA when regular supply of alpha-linolenic essential fats are ensured. EPA is also a precursor to DHA. As the synthesis of ARA, a n-6 FA, competes for the same enzymes, in the presence of high levels of n-6 FA, the synthesis of 20:5(n−3)FA is affected. The metabolization of 20:5(n−3)FA from ALA is further reduced in the case of diabetes and inflammatory diseases.

Benefits of eicosapentaenoic acid

  • Eicosapentaenoic acid has anti-inflammatory, antithrombotic, triglyceride-lowering and immunomodulatory activities.
  • Several studies have indicated that fish oil helps in reducing the symptoms and inflammation in rheumatoid arthritis.
  • Eicosapentaenoic acid is used for high blood pressure in pregnancies.
  • Low blood levels of 20:5(n−3)FA have been associated with attention deficit-hyperactivity disorder (ADHD).
  • EPA is found to be effective in reducing the symptoms and incidence of Raynaud’s syndrome.
  • In people who are hyperglyceridemic, 20:5(n−3)FA is found to reduce the elevated triglycerides by inhibiting lipogenesis and stimulating oxidation.
  • The antiatherogenic functions of omega-3 fats give protection against cardiovascular diseases. There is also improved endothelial function and increased elasticity.
  • Levels of n-3 fats in plasma have a stabilizing effect on the atherosclerotic plaques.
  • In research studies eicosapentaenoic acid was found to inhibit proliferation of tumor cells in vitro.
  • The lipid lowering effects, reducing clotting and reducing platelet aggregation of 20:5(n−3)FA are important in preventive treatment of cardiovascular diseases.
  • There is epidemiological evidence to suggest that people consuming oily fish and marine products rich in 20:5(n−3)FA have reduced risk of cancer.
  • Phospholipid abnormalities of the erythrocyte membranes are described in schizophrenia. The use of fish oil in limited clinical trials has given encouraging results.
  • In case of ulcerative colitis, the administration of fish oil has given positive results in reducing the symptoms.
  • Elevated homocysteine levels are linked to old age diseases like Alzheimer’s disease, Parkinson’s disease, and osteoporosis. Eicosapentaenoic acid is found to lower homocysteine levels.
  • Age-related macular degeneration is prevented in persons comsuming fish oil.
  • Along with antidepressants eicosapentaenoic fat is effective in treating depression.

Precautions, interactions and contraindications

Fish oil supplements may be given to infants and pregnant women only on the advice of health care professional as unregulated use or dosage may have negative effects.
Fish oils have side effects like belching, nausea, heartburn and diarrhea. These negative effects may go if it is taken along with principal meal.
As eicosapentaenoic acid in the fish oils have blood thinning effects, those taking anticoagulant medications like aspirin, heparin, warfarin etc must not take fish oils without consulting their doctor as there is the risk of bleeding.
Eicosapentaenoic acid has potential for lowering blood pressure and taking medications for hypertension along with fish oil may cause blood pressure to go too low.
As the effects of diabetes drugs may get elevated, consult your doctor before taking fish oil.
In persons with aspirin sensitivity, fish oil supplements may affect their breathing.
Image source: http://en.wikipedia.org/wiki/File:EPAnumbering.png
Image author: Edgar181
Image license: public domain

Current topic in Nutrition, deficiency & diseases: Eicosapentaenoic acid (EPA)

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