Fish oil is a dietary source of omega-3 fatty acids derived from fish tissues. Fish oil contains three omega-3s called docosahexaenoic acid (DHA), alpha-linolenic acid (ALA) and eicosapentaenoic acid (EPA).

Pros and Cons of Fish Oil

The sources of fish oil include species like herring, tuna, anchovies, and mackerel. Around 30% of fish oil is made up of omega-3s, while the remaining 70% is made up of other fats. Other essential vitamins, like vitamins A and D, are also present in the fish oils.

Fish oils are an important part of our diet, especially in these modern times as people are unaware of these fatty acids. Human bodies can synthesis most of the fatty acids through its own metabolic processes but these fatty acids can only be obtained from diets like fishes, nuts and vegetables.

So, it is essential that we know about the effects on the physiology of the body. Furthermore, modern diets are high in omega-6 in comparison to omega-3. Omega-6 is another type of fatty acids that causes inflammation by the production of eicosanoids.

Advantages of Fish Oil

1. Omega-3s can Decrease the Risk of Heart Diseases

Cardiovascular diseases like heart attacks and strokes are seen in drastically fewer numbers in communities with high fish containing diets like the Eskimos in Greenland.

Researchers have observed that the consumption of fish is directly related to heart health. A study was done in 1989 by taking groups of people where one group had a diet with high omega-6 (plant-based diet) while the other group had food with high omega-3(fish oil derived). The group with the omega 3 diet showed a 29% reduction in fatal cardiac arrhythmias. Thus, the benefits of fish oil in coronary heart disease can not be overlooked.

2. They Can Fight Depression and Anxiety

Anxiety and depression is another major problem in our modern society. Their symptoms include sadness, lethargy, hopelessness, and nervousness.

EPA, one of the types of omega-3s has been tested as an anti-depressant drug. It has shown that together with other drugs like fluoxetine (selective serotonin reuptake inhibitors (SSRI) anti-depressants) has shown therapeutic effect in major depressive disorder.

Generally, people who consume omega-3s infrequent basis show low depression or anxiety. And people with depression who start taking them show reduce in the level of their depression.

3. They Can Aid in Managing High Blood Pressure

Fish oil has shown a decrease in decrease hypertension in patients by a mean value of 5 mmHg according to research. Daily doses of 0.7 g EPA+DHA has shown a reduction of blood pressure of patients with systolic hypertension.

4. Acts as Anti-inflammatory Agents

Fish oil (mainly EPA) also reduces inflammation of the cells of the body. They suppress the production of a type of acid known as Arachidonic acids. Arachidonic acids, in turn, cannot produce eicosanoids which causes inflammation in the body.

5. They can Reduce the Risk of Plaque Formation

Plaques are solid masses formed in the blood vessels that lead to heart diseases like atherosclerosis. They can lead to blockage of the arteries that supply blood to different parts of the body.

Fish oil has shown increased vasodilatation and platelet activation, especially in cigarette smokers, which can lead to decreased risk of formation of plaques in the walls of the blood vessels.

Disadvantages of Fish Oil

1. It gives off a fishy taste

It comes with no surprise that the fish oils give off a fishy smell which might be quite annoying for some people, especially for vegetarians who take fish oil supplements as a substitute to eating meat.

2. Diarrhea may occur

If the fish oil is taken in high doses, diarrhea may occur due to stomach upset. Typically it takes more than 3 gm dose of fish oil per day to show the symptoms which should reside once the dosage is limited to the recommended dose.

It is the most common side effect along with other gastrointestinal symptoms like flatulence. Alternatives like flaxseed oil, which is a vegetative alternative also show laxative effects and leads to an increase in the peristaltic bowel movements.

3. Occurrence of Acid Reflux

Acid reflux may occur due to its high concentration of fat. The major symptom includes heartburn while other minor symptoms like belching and stomach discomfort may also be present.

Reducing the dose of fish oil after the occurrence of the acid reflux and taking meal along with fish oil helps reduce the effects of the fish oil.

4. May lead to Hypotension

Fish oil can decrease the systolic blood pressure which is useful for patients with hypertensive diseases. But at the same time, people with pre-existing hypotension may have to refer to a doctor before using fish oil on a regular basis.

5. May Increase Blood Sugar Level

Increase in blood sugar level with the use of fish oil supplements is seen, especially in patients with diabetic condition. But this is said to be present only in high doses of fish oil’s acid ingestion.
A research study showed that in a group of diabetes type 2 patients, ingesting 8 gm of omega 3 fatty acid for 8 weeks leads to an increase in fasting plasma glucose level by 22% and the increase in meal stimulated glucose level by 35%. Omega-3 fatty acids of the fish oil increases the level of glucose in the blood

Other researchers on the other have been showing that that fish oil has no effect in the blood glucose level in other conflicting researches.

6. May Increase Bleeding

Fish oil prevents blood clot formation which leads to bleeding. Bleeding, in this case, is not severe and only is found in the form of nose bleeding and/or nose bleeding.

It is, for this reason, doctors usually don’t prescribe fish oils prior to surgery, patients with hemophilia and other congenital disease related to bleeding and while taking drugs decreases the viscosity of blood.
May cause vitamin A toxicity

The content of vitamin A may be high in some of the fish oil supplements and they can be toxic if consumed high volume. Certain side effects like dizziness, nausea and skin irritation.

Long term, it may cause liver damage and even lead to liver failure. But this is an unlikely event unless taken huge doses of fish oil.


Fish oil is an essential fatty acid that is required for the body to improve its immune status and fight inflammation. The benefits of fish oil are clearly seen in the difference of health between people with a diet containing fish and people with a diet without fish and fish oil.

However, the cons of the fish oil cannot be overlooked. Though it shows side effects in the human body, taking fish oils in the recommended doses shows very less side effects.

The recommended dose of fish oil is a range around 250-500 milligrams of combined EPA and DHA per day.

The pros of taking fish oil in this range outweigh the cons of fish oil.



My full name is Ruben Napit and I am doing dentistry in Kathmandu University. I am from bhaktapur. I completed my school and college education from little Angel's school. I have interests in aviation, painting, music and football.