Omega-3 Fatty Acids: What Are They and Why Are They Important?

The word “essential” means absolutely necessary, very important – and that’s what Omega-3 fatty acids are – crucial to our heart health, our blood pressure and the concentration of blood lipids, but they are also important to our brain, joints and eyes. If we discuss Pharmacology for a second – Omega-3s are “essential” because our body cannot synthetize them and we receive them through diet or supplementation.

So, what are Omega-3 fatty acids?

Well, chemically speaking, they are fatty acids rich with double bonds and they can be short – and long chain. Want to see what they look like? Here’s a picture of ALA – short for alpha-linolenic acid, an essential fatty acid derived from plants.

ALA numbering

By Edgar181 via Wikimedia Commons

Physiologically speaking, they are an integral component of our cell membranes and influence the function of the cell receptors in them. They help the body make hormones, that have a say in blood clotting, contraction and relaxation of artery walls, and inflammation. But, their role in our body does not end there! They also bind to receptors in our cells which regulate genetic function.

Several different omega-3s exist, but the three main are ALA (alpha-linolenic acid), EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). EPA and DHA are long-chain omega-3 fatty acids. Their reputation for reducing the risk of exposure to stroke and heart diseases is unmatched. ALA is an essential fatty acid that (primarily) our liver can convert to EPA and then to DHA, but this transformation is very limited and generates less than 15% of both long chain fatty acids. This is why we have to consume EPA and DHA through food.

What are the main sources of omega-3 fatty acids?

The process of converting ALA to DHA is not as efficient as it should be. Therefore, it is better to focus on dietary sources rather than relying on the body to perform the conversion.

ALA is present in plant oils, such as:

  • Flaxseed
  • Soybean
  • Canola oils

EPA and DHA are present in fish, fish oils and krill oils. Some fatty fish that contain these valuable acids are:

  • Trout.
  • Kippers.
  • Herring.
  • Sardines.
  • Whitebait.
  • Marlin.
  • Pilchards.
  • Sprats.
  • Salmon.

A few types of white fish are also renowned for the generous amount of omega-3 fatty acids they provide. In this case, the types of white fish we should consume to obtain all the omega-3 essential fats we need include:

  • Flounder
  • Plaice
  • Cod
  • Haddock
  • Coley
  • Dover sole.
  • Dab

EPA and DHA are not synthetized by the fish, though. They are synthetized by microalgae, which are eaten by these fish. They then accumulate in the fish’ tissues.

Some shellfish also contain omega-3s, such as:

  • Mussels
  • Oysters
  • Squid
  • Crab



Omega-3s and cardiovascular health – an uphill road.

When talking about cardiovascular disease, we talk about conditions involving the heart and the blood vessels. We call this system cardiovascular system. Conditions and diseases include heart diseases, strokes, high blood pressure and atherosclerosis (artery narrows due to the build-up of plaque).

So do omega-3s really help us fight this conditions?

Well, the results from different studies are mixed. Some studies state that there is an inconclusive evidence, that long chain fatty acids have a beneficial role in preventing cardiovascular diseases. Other studies claim that high doses of omega-3s may be beneficial in the prevention of some cardiovascular diseases, like myocardial infarction among people with a history of this disease.

There is no evidence that omega-3s help prevent heart attacks, arrhythmias and strokes.

Certain studies have shown positive effects on conditions involving circulatory effects, like for example – varicose veins. In this case, EPA and DHA may stimulate blood circulation and therefore improve the condition. Some evidence suggests that omega-3s moderately lower blood pressure and reduce blood triglyceride levels.

Omega-3s vs. inflammation 

EPA and DHA give a significant helping hand in fighting inflammation by lowering the effects of inflammation blood markers like C-reactive protein (CRP), interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α). The concentration of these substances is very high during an inflammation. The mechanism of action is quite complex, but the anti-oxidative effect of these fatty acids may explain their influence on the inflammation markers.

Eyeing these omega-3s…

There is now clear evidence that omega-3s are essential for normal eye development. Babies get their omega-3s (mainly DHA) through mother’s milk or formulae. DHA is essential for their eye-sight development.

It is also proven that omega-3s prevent age-related macular degeneration and associated sight loss.  Visual impairment is a global problem. According to the International Agency for the Prevention of Blindness (IAPB), 253 million people in the world are blind and vision-impaired.

Many studies have confirmed that nutrients, such as lutein, zeaxanthin, vitamin C, vitamin E, zinc and copper, as well as omega-3s – EPA and DHA are the most proven nutritional therapy for reducing the rate of advanced age-related macular degeneration.

 Ancient omega-3s for the modern brain!

Omega-3s (especially DHA) are very important for normal brain function. Studies have shown that DHA deficit in perinatal (right before and right after birth) brain are associated with many different brain abnormalities, such as neurocognitive deficits. It is also associated with mental health conditions, like anxiety, aggression and depression.

DHA is the most abundant fatty acid in our brain. As such, it supports many cell membrane properties, and for this reason, it is an important component of brain growth and myelination.

Time to oil the joints!

joint pain

Stiff joints?  Studies have found that fish oil supplements may help to relieve sore joints and morning stiffness. Researches show, that omega-3s affect certain immune system cells’ function (dendritic cells, T-cells) and influence the production of inflammatory cytokines and reactive oxygen species. These are anti-inflammatory and anti-oxidative functions, which help the body fight the disease.


I’m sure – this question is burning you inside  – are there any side effects?

Well, besides the fishy aftertaste, gastrointestinal disturbances (nausea, bloating, belching),

prolonged bleeding time (this is for people who take anticoagulant medication – they should consult their doctors about their diet and food supplementation), and exposure to environmental contaminants with certain fish species – there’s really nothing to worry about.  Little sarcasm is healthy. Scientists say so! It is recommended, though, that a (relatively) healthy person should eat at least two servings of fatty fish per week along with other foods rich in omega-3s.

Pregnant women should be careful and avoid marlins, swordfish, and sharks because of the high content of mercury and environmental contaminants in those fish. Some of the toxic substances in those fish are methyl-mercury, polychlorinated biphenyls and dioxins.  The last two substances are known endocrine disruptors – chemicals that interfere with the hormonal system of people and animals. They should be avoided especially by pregnant women and children!

What about omega-3 supplements? Are they worth the hassle?

Omega-3 fatty acid food supplements are usually in a form of a capsule or fish oil. Fish oil can be:

  • Cod liver oil.
  • Standard body fish oil.
  • Fish oil concentrate.

Cod liver oil is also rich in vitamins A and D. These vitamins are fat-soluble and not water-soluble like vitamins B and C. This means that while we excrete vitamins B and C with our urine, we do not excrete A and D the same way. We accumulate vitamins A and D in our body and their levels can become toxic.  This is why we should be careful when using Cod liver oil.

Doses of vitamin A are calculated as IU (International Units) per kg of weight, and chronic toxicity can occur when high doses of vitamin A are daily consumed. If we’re talking in numbers, acute toxicity is at 25 000 IU/kg and chronic toxicity occurs at 4000 IU/kg daily for 6-15 months.

The food supplement industry is one of the fastest growing industries in the world. In 2015 the expenditures grew up to 60 billion $ worldwide. Unlike medications, which go through strict safety and effectiveness requirements, food supplements are treated as a category of food and do not go through the same regulatory process as drugs do. Drugs are considered unsafe until proven safe and dietary supplements are considered safe until proven unsafe. Are you dizzy yet?


To put things in a nutshell: Safety of the food supplement is up to the manufacturer not the Food and Drug Administration of the country you live in. The Food and Drug Administration steps in when the supplement is proven to be unsafe.

There have been cases where herbal food supplements are tainted with germs, pesticides or toxic heavy metals. Some do not contain everything that’s listed on the label and others contain things that aren’t written on the tag (like fillers and substitutions). I will mention endocrine disruptors again – they are also present in some food supplements.

So how to buy the good stuff and how to protect ourselves?

We should NEVER buy:

  • Supplements that claim to treat an illness or cure a medical condition.
  • Advertised products through mass e-mails.
  • Products marketed mainly in a foreign language.

Bottom line: we should follow a healthy, balanced diet, carefully read labels of supplements, and avoid using doses that exceed the Recommended Daily Amounts (RDAs). When in doubt – ask for advice from a dietitian, pharmacist or medical doctor before choosing a dietary supplement.

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Bojana Najdovska

Master of pharmacy and nutritional consultant. Blogger. Black tea lover. Dog person. Worried about the Environment and exposure to endocrine disruptors.

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    1. Hello, there are mixed comments from experts about Omega 6 fatty acids. The reason is, that on one hand Omega 6 fatty acids lower harmful LDL cholesterol and boost protective HDL, as well as help keep blood sugar in check by improving the body’s sensitivity to insulin; but on the other hand, our body can convert the most common one, linolenic acid, into another fatty acid called arachidonic acid, and arachidonic acid is used for molecules that can promote inflammation, blood clotting, and the constriction of blood vessels. But the body also converts arachidonic acid into molecules that calm inflammation and fight blood clots. So, the best thing to do is eat more Omega 3 fatty acids (salmon, fish oil, flaxseed) to improve the Omega 3 : Omega 6 Ratio.

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