Fish Oil Facts - What are the Health Benefits Of Fish Oil (If Any)?

Healthy Living

A handful of fish oil supplements taken because of the health benefits of fish oil

Fish oil has been one of the most popular health supplements for decades- the world fish oil market is worth $1.7 billion dollars in 2018. The claimed health benefits of taking fish oil are due to Omega-3 fatty acids and include:

  • Relief from arthritis
  • Reduction in lupus symptoms
  • Help with depression and ADHD
  • A reduction of risk factors associated with heart disease
  • Improved eye health
  • Supporting foetal brain development
  • Help with asthma symptoms
  • Better skin and hair health

But is fish oil really the wonder supplement? It’s been thoroughly studied - some studies show health benefits while other recent studies cast doubts on some (particularly the claimed reduction in heart disease and stroke). There are also some side effects of fish oil to beware of. In this guide, we’ll take a thorough look at the pros and cons of taking a fish oil supplement to help you decide if it’s worth it for you.

What is Fish Oil?

Fish oil is the fat contained in fish tissue. Some fish - like herring, tuna, mackerel - are more oily than others. About 30% of fish oil is made up of omega-3, and the remaining 70% are fats. Omega-3 fatty acids have health benefits to humans, so the World Health Organisation (WHO) recommends eating 1-2 servings of fish each week to protect against some diseases. Some people prefer to take a daily fish oil supplement rather than eating fish.   


History of Fish Oil

In the 1960s, doctors discovered that eating more polyunsaturated fatty acids could lower blood cholesterol levels. Danish scientists also made the connection that Greenland’s indigenous people who ate a diet high in fish had lower mortality rates from coronary heart disease than other Danes.

Raw salmon - source of lean protein and heart health benefits

In 1979, a scientific paper concluded that eating fish oil reduced the risk of coronary disease. This caused an explosion in the popularity of omega-3 fish oil supplements worldwide from the early 1980s.


What Are the Health Benefits of Omega-3s?

Omega-3 fatty acids are what gives fish oil its health benefits. The two main omega-3 long-chain fatty acids are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).  DHA is needed for growth and development of the retina and brain and between 5 and 65, the body needs more EPA than DHA because it helps prevent mental health issues, heart problems, joint and bone conditions.   

Numerous research studies and trials have been conducted on fish oil supplements around the world to reveal the following health benefits:



Fish oil is best known for its anti-inflammatory effect in helping people living with arthritis.

Arthritis Australia reports that current research suggests omega-3 can help people with inflammatory arthritis including rheumatoid arthritis, ankylosing spondylitis and psoriatic arthritis.

Some omega-3 fats can reduce inflammation from arthritis and may help to relieve stiffness and joint pain. The effect is similar to non-steroid anti-inflammatory drugs (NSAIDs), and fish oil allows some people living with arthritis to reduce the drugs they need to take.


Heart Disease Risk Factors

Many Australians take fish oil supplements to reduce the risk factors associated with heart disease. It is claimed that fish oil can help with the following:

Cholesterol – fish oil can increase the good cholesterol (HDL) and lower the bad cholesterol (LDL).

Triglycerides – fish oil can lower the levels by 15-30%.

Plaque – by taking fish oil you could reduce the artery-hardening plaque forming on the walls of arteries

Blood pressure – fish oil is claimed to help lower blood pressure

Fatal arrhythmias – in some people an abnormal heart rhythm can cause a heart attack

However, it is important to note that the most recent research on fish oil has found that many of the claims for fish oil improving heart health are inconclusive. A 2013 study found that omega-3 fatty acid supplements did not necessarily reduce the risk of heart attack, stroke or death from heart disease in patients with multiple cardiovascular risk factors. You can read more about this later in the article under the heading “Research on Heart Disease and Fish Oil”.


A study on sufferers of the autoimmune disease lupus showed that after six months of taking a fish oil supplement they had improved quality of life and reduced fatigue.

Depression and Mental Disorders

People with depression may have low levels of the brain chemicals EPA and DHA. Some studies have shown that omega-3 fatty acids can improve the symptoms of mild to moderate depression. High levels of fish oil can prevent the onset of mental disorders and reduce the symptoms of bipolar disorder and schizophrenia.

ADHD Symptoms

There is some research that recommends fish oil for reducing the symptoms of ADHD and improving children’s mental skills. It is also thought that fish oil may improve hyperactivity, inattention, impulsiveness and aggression in children.    

Foetal Growth and Brain Development

Our brains are rich in the omega-3 fatty acid DHA, so a link has been made between fish oil and brain development. It is thought that fish oil supplements taken by pregnant women may assist with foetal growth and brain development. The fish oil may also help with infant hand and eye coordination.

Another study has shown that children are 24-29% less likely to suffer from asthma in their early life if their mother took fish oil while pregnant.

New Research Findings on Health Benefits of Fish Oil

Research has continued into the effectiveness of fish oil supplements. Findings in the last few years have placed doubt on some fish oil health claims.

Research on Heart Disease and Fish Oil

Fish oil capsules are marketed as reducing the risk of coronary heart disease, but this was questioned after a report released last year by the American Heart Association (AHA). It states there is evidence to show that fish oil supplements ‘may slightly reduce your risk of dying of heart failure or after a recent heart attack. However, they do not prevent heart disease’.

After 15 years of trials, the AHA has confirmed there is no evidence that fish oil improves the heart health of people who are prone to cardiovascular disease including people with diabetes, atrial fibrillation or stroke. This new information is in direct contrast to the Association’s statement in 2002.

It brings into question the Deloitte Access Economics Report in 2012 that estimated the Australian economy could save $4.2 billion in costs related to cardiovascular disease if patients took fish oil supplements. It's important to look at all information available, including from overseas sources, to make sure you are informed.

New Research on Fish Oil and Stroke

Fish oil supplements were also thought to reduce your risk of stroke. However, the results of 38 studies revealed that you need to eat oily fish rather than take fish oil capsules to reduce your risk of stroke. Eating fish at least twice per week reduces the chance of thrombotic stroke but doesn’t change the risk of hemorrhagic stroke.

Thrombotic stroke occurs when a blood clot forms in the brain’s artery-blocking blood to part of the brain. A hemorrhagic stroke occurs after a rupture in a weakened blood vessel in the brain.  


What Are the Side Effects of Fish Oil Supplements?

Some people will experience side effects from taking fish oil capsules while others won’t notice any. Fish oil has a blood thinning effect that is responsible for most side effects. The most common side effects are:

Nose Bleeds

A common complaint of fish oil supplement takers is nosebleeds. If the nosebleeds occur regularly or they are difficult to stop, see your doctor.

Bleeding Gums

Brushing your teeth can cause gums to bleed more often when taking a fish oil supplement.


Taking fish oil supplements may increase the number of bruises which indicates there is bleeding under the skin.   


Fish oil supplements can repeat on you causing an unpleasant fishy burp or aftertaste.   

Hemorrhagic Stroke

In rare instances, blood vessels may burst and rupture causing bleeding in the brain. Symptoms include slurred speech, dizziness, confusion, loss of consciousness. Immediate medical attention is required - phone an ambulance if you notice these symptoms in someone.  

Further reading: Find out more about fish oil side effects and interactions here.

Other Potential Risks When Taking Fish Oil

Many people are of the opinion that a daily fish oil supplement can’t hurt if they don’t eat the recommended intake of fish each week. But is it risk-free?  

Mercury Poisoning

People are aware of the risk of high levels of mercury from eating more than recommended doses of older, larger predatory fish such as shark. However, people often wonder if mercury is evident in fish oil supplements.  

During the manufacturing process of fish oil supplements, it is possible to separate out most harmful elements like mercury and retain the nutrients. Fish with low mercury levels such as sardines, salmon, whitefish and anchovies are best for supplements. While it is almost impossible to produce a fish oil with no mercury, these two factors can ensure the levels are negligible.

a school of tuna - rich sourch of omega 3 fatty acids but with the risk of heavy metals

Chemicals in Fish Oil

Banned in the late 1970s after a link to cancer was made, the toxic Polychlorinated biphenyl (PCB) chemicals had already entered the food chain. PCBs and dioxins are in fish exposed to waterways containing soil runoff. These chemicals are in some overseas fish supplements.  

The Australian Therapeutic Goods Administration classifies fish oil as a nutritional substance and regulates them at a federal level. They set standards for heavy metals, mercury and chemicals in supplements so don’t buy supplements over the internet unless you are confident of the manufacturing quality.

Bleeding Disorders

Fish oil stops platelets sticking together and thins the blood. People with Hemophilia or Von Willebrand’s disease whose blood doesn’t clot well shouldn’t take fish oil supplements.


Many people with seafood allergies safely take fish oil supplements, but people with an allergy to fish are recommended to get their omega-3 fatty acid through ground flax seeds.  

Mixing Medications and Fish Oil

Many people believe that because you buy a natural supplement over the counter, there is no risk. While this is true for most supplements, the risks occur when supplements and prescribed medications are mixed. Before taking any supplement, you should consult your doctor, especially if you are taking medications.

Because fish oil thins the blood people taking blood-thinning medications such as Warfarin® are at risk of excessive bleeding after a cut or injury. People taking a daily low dose of aspirin to prevent heart attack may be at risk of too much blood thinning.

After consuming fish oil, platelets in the blood decrease in clotting activity. So people taking an anticoagulant or
antiplatelet medications such as Heparin®, Clopidogrel®, Dipyridamole® and Enoxaparin® need to consult their doctor before taking fish oil supplements.

Mixing Herbal Supplements and Fish Oil

Some herbal supplements also have the effect of thinning the blood. Gingko, garlic, oregano and willow are all known to thin the blood when taken in large doses.

Age of Fish Oil Capsules

Fish oil capsules oxidise where oxygen in the air decomposes the oil causing it to become rancid. Storing capsules in a cool, dry and dark place can increase their life but be sure to check the use by date and if it smells rancid, discard the container.    


How Much Fish Oil Do you Need Per Day?  

When buying fish oil, it is important to look at how much omega-3 fatty acids the fish oil tablets provide.

The average Australian National Health and Medical Research Council (NHMRC) recommends men have a daily intake of 610mg and women 430mg of DHA + EPA. The minimum requirement is 160mg for men and 90mg for women. To be effective in relieving arthritis pain, a much higher 3000mg of DHA + EPA is recommended.


What About the Other Sources of Fish Oil?

It’s not just fish oil that has health benefits. Cod liver oil was used before fish oil to treat night blindness and rickets from the late 1930s. Krill oil is the latest entrant to the fish oil market and is claiming to have different health benefits to fish oil.

Should you Take Fish Oil or Krill Oil?

Fish oil has been the most popular supplement for many years, but in recent years, krill oil manufacturers have made claims that it has more health benefits than fish oil.

The main difference between the two is that krill oil contains phospholipids, the same chemical structure as the fats in human cell membranes whereas fish oil includes triglycerides. One research study reported that some krill oil supplements don’t contain the same amount of phospholipids as natural krill oil.

One study reported higher absorption rates of omega-3 fatty acids in respondents who had taken krill oil compared to fish oil or a placebo. However, the jury is still out on switching from fish oil to the more expensive krill oil supplements due to a lack of research.  

So, is Fish Oil Good for You?

Humans need omega-3 fatty acids for good general health. A fish oil supplement contains omega-3s, but the research indicates that actually eating the recommended amount of fish and other seafood as part of a balanced diet is better for your health rather than just taking a supplement. Seafood is also a good source of lean protein and other essential nutrients. Don’t forget other sources of omega-3 fats like flaxseed, walnuts, chia seeds and canola oil.

The list of health benefits derived from fish oil is still impressive. When taken as a ‘treatment’ for symptoms of a disorder, consumers can gauge for themselves if fish oil is effective or not. When it comes to taking supplements as a prevention of disease, it’s more difficult to determine the effectiveness. Only you and your doctor can decide if fish oil is a worthwhile supplement. As with all things health-related, it’s always best seek professional advice from your own GP before taking any supplements.

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