What Are Omega-3 Fatty Acids ?

Fish oil is a great source of omega-3 fatty acids.
Image by Monfocus c/o Pixabay.

The omega-3 fatty acids are an absolute for the body to function properly. They can only be ingested in food and are described as essential. They are not produced in the body. They are also described as polyunsaturated fatty acids and come from a variety of sources. 

Just what are omega-3 fatty acids exactly? How much do you need? And what do all those abbreviations — EPA, DHA, and ALA — really mean? Here’s a rundown of the essential omega-3 facts you need to know.


There are three types:-

There are three types of omega-3 fatty acid important in human nutrition:

  • alpha-linolenic acid (ALA)
  • eicosapentaenoic acid (EPA)
  • docosahexaenoic acid (DHA)

Chemical Structure Of the Omega-3 Fatty Acids

They have a cis-double bond system within a straight chain. That double bond is a key feature of these molecules.

The term omega-3 (a.k.a. “n-3”, “ω-3”) tells us the first double bond exists as the third carbon-carbon bond from the terminal methyl end (ω) of the carbon chain. At the other end is a carboxylic group -COOH.

The carbon number is each of the fatty acids is the following:- 

alpha-linolenic acid (18:3, ALA),

eicosapentaenoic acid (20:5, EPA),

docosahexaenoic acid (22:6, DHA).

The first number signifies the number of carbon atoms in the straight chain. The second number indicates the number of double bonds in the molecule. Being cis double bonds, there are two hydrogen atoms on the same side of the molecule unlike as in ‘trans’.

Health Benefits of Omega-3 Fatty Acids.

There are many health benefits of omega-3 fatty acids. Research shows strong evidence that the omega-3s EPA and DHA can boost heart health and lower triglycerides. And there are studies showing that omega-3 fatty acids may help with other conditions including rheumatoid arthritis, depression, and many more. Even so, the ability of omega-3 fatty acids to treat various metabolic conditions as well as reducing cardiac and sudden death, stroke, myocardial infarction is still quite controversial (Lorente-Cebrián et al., 2013).

One of the main sources of essential  omega-3 fatty acids is in fish. Other sources include  fish oils, milk, and cultivated marine algae.


Omega-3 fatty acid ingestion is associated with reducing various inflammatory conditions such as rheumatoid arthritis, arthrosis, inflammatory intestinal diseases and skin diseases such as psoriasis.

The omega-3 fatty acid called EPA is converted via the enzyme 5-lipoxygenase to a compound called 5-HPEPE which is converted to LTA5 and then to LTD5. These are anti-inflammatory compounds that act in the human body. A series of other anti-inflammatory compounds are produced from EPA such as the E-series Resolvins (RvE1) and the A3/I3-isoprostanes (IsoPs). There is some evidence that the omega-3 fatty acids are also converted to various cannabinoids which help fight inflammation.

DHA is converted to the D-series resolvins (RvD), a group of docosatrienes such as Protectin D1 and aspirin triggered RvD’s called (AT)-RvD’s.

Low grade inflammation is associated with an increased cardiovascular mortality rate. According to the study reported on the subject in the International Journal of Cardiology (2009 Feb 13th):-

“Inflammatory markers seem to be independent predictors of CV mortality in the elderly part of the general population”.

Heart Health Benefits

One study reported in Hypertension in 2007 was the INTERMAP study (Ueshima et al., 2007). This was an international cross-sectional epidemiological study of 4,680 men and women with ages from 40 to 59. They came from 17 population-based samples in the United Kingdom, China, Japan and the United States. The overall conclusion was that:-

“food omega-3 PUFA intake related inversely to blood pressure, including in nonhypertensive persons, with small estimated effect size, omega-3 PUFA may contribute to prevention and control of adverse blood pressure levels”.

Another study examined  1,822 men over 30 years. They found that (1) mortality from CHD was 38% lower, (2)  myocardial infarction was 67% lower in men who consumed an average of 35 g (1.2 ounces) of fish daily compared to men who did not eat as much. The effect was attributed in part to the consumption of fish oil in the fish although other dietary aspects could not be ruled out either.

Their is also a role for n-3 fatty acids in treating hypertriglyceridemia which is a high level of triacylglycerol in the blood. According to the American Journal of Clinical Nutrition (Jacobson, 2008):-

“Omega-3 fatty acids when used in doses of 3-4g/day eicosapentaenoic acid and docosahexaenoic acid have profound effects on triacylglycerol concentrations”.

The association of consuming omega-3 fatty acids is very strongly associated with reducing serious cardiovascular events.

Rheumatoid Arthritis

Fish oil supplements containing both EPA and DHA can reduce stiffness and joint pain. They also appear to improve the effectiveness of anti-inflammatory drugs.

Reduction Of Symptoms Of ADHD in Children using Omega-3 Fatty Acids.

Some children can suffer from ADHD (Attention deficit hyperactivity disorder). This shows itself as a behavioural disorder that involves high levels of hyperactivity coupled to an inability to concentrate for long and being impulsive (Giacobini et al., 2018).

A few studies have indicated that children with ADHD have low levels of omega-3 fatty acids in their blood compared to children of similar age without diagnosed ADHD (Stevens et al., 1995). Supplementation is claimed to improve their memory, ability to think especially through problems and overall learning capacity.

Its worth noting that omega-3 supplements are not to be used as a primary treatment because research has not proved any of these benefits conclusively.


People that eat plenty of fish as well as foods high in omega-3s have lower levels of depression. Fish oil can also improve the effects of antidepressants. There is also a case for them reduce the impact of depression from bipolar disorder.

Regulatory Aspects On Omega-3 Fatty Acids

EFSA (European Food Safety Authority) concluded back in 2012 that daily supplementation with 5g of long-chain omega-3 fatty acids was of not a safety issue for adults.

Food Intake Guidelines

The American Heart Association’s 2006 Diet and Lifestyle Recommendation (Lichtenstein et al., 2006) for reducing the cardiovascular disease risk is to consume fish, especially oily fish, at least twice a week. The 2015–2020 Dietary Guidelines for Americans and the Scientific Report of the 2015 US Dietary Guidelines Advisory Committee recommend at least 2 servings per week of seafood to provide an average of 250 mg eicosapentaenoic acid plus docosahexaenoic acid per day in place of other animal sources of protein (USDHHS & USDA, 2015a & b). This report offers advice on incorporating seafood into a healthy US-style eating pattern and also a healthy Mediterranean-style eating pattern.

Availability in Supplements

Omega-3 Fish Oils are commonly available as pure samples of fish derived essential fatty acids. Most supplements either come in liquid form or is softgel capsules. Most are suitable for pescatarians.


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Giacobini, M., Medin, E., Ahnemark, E., Russo, L. J., & Carlqvist, P. (2018). Prevalence, patient characteristics, and pharmacological treatment of children, adolescents, and adults diagnosed with ADHD in Sweden. Journal of Attention Disorders22(1), pp. 3-13. (Article)

Jacobson, T. A. (2008). Role of n− 3 fatty acids in the treatment of hypertriglyceridemia and cardiovascular disease. The American Journal of Clinical Nutrition87(6), 1981S-1990S. (Article)

Lichtenstein AH, Appel LJ, Brands M, Carnethon M, Daniels S, Franch HA, Franklin B, Kris-Etherton P, Harris WS, Howard B, Karanja N, Lefevre M, Rudel L, Sacks F, Van Horn L, Winston M, Wylie-Rosett J. (2006) Diet and lifestyle recommendations revision 2006: a scientific statement from the American Heart Association Nutrition Committee [published corrections appear in Circulation. 2006;114:e27 and Circulation. 114:e629]. Circulation2006; 114:82–96. doi: 10.1161/CIRCULATIONAHA.106.176158 (Article)

Lorente-Cebrián, S., Costa, A. G., Navas-Carretero, S., Zabala, M., Martínez, J. A., & Moreno-Aliaga, M. J. (2013). Role of omega-3 fatty acids in obesity, metabolic syndrome, and cardiovascular diseases: a review of the evidence. Journal of physiology and Biochemistry69(3), pp. 633-651.

Stevens, L. J., Zentall, S. S., Deck, J. L., Abate, M. L., Watkins, B. A., Lipp, S. R., & Burgess, J. R. (1995). Essential fatty acid metabolism in boys with attention-deficit hyperactivity disorder. The American Journal of Clinical Nutrition, 62(4), pp. 761-768. (Article)

Ueshima, H., Stamler, J., Elliott, P., Chan, Q., Brown, I. J., Carnethon, M. R., … & Steffen, L. M. (2007). Food omega-3 fatty acid intake of individuals (total, linolenic acid, long-chain) and their blood pressure: INTERMAP study. Hypertension50(2), pp. 313-319.

US Department of Health and Human Services and US Department of Agriculture (2015a). 2015–2020 Dietary Guidelines for Americans. 8th ed. Washington, DCUS Government Printing Office2015.

US Department of Agriculture and US Department of Health and Human Services (2015b). Scientific Report of the 2015 US Dietary Guidelines Advisory CommitteeWashington, DCUS Government Printing Office2015.

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