Fish oil, commonly referred to as omega-3, is among the most sought-after dietary supplements. It is widely promoted for its potential benefits, such as enhancing heart health, improving mood, alleviating inflammation, and supporting overall well-being.
The question arises: How much of this is supported by scientific research, and when might it be appropriate to consider fish oil supplements?
A Long History
Fish oil has been utilized for centuries.
Modern-day interest in fish oil surged during the 1970s when researchers studying Inuit diets uncovered the heart-protective benefits of omega-3 fatty acids.
By the 1980s, fish oil capsules began to appear on the market as a convenient method for obtaining these beneficial fats.
What’s in Fish Oil?
Fish oil is derived from oily fish, including salmon, sardines, tuna, herring, and mackerel. It is high in omega-3 polyunsaturated fatty acids (PUFAs), primarily eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
These omega-3s are vital for cellular function. Each cell in our body is encased by a thin, flexible membrane that serves as a protective barrier. This membrane keeps the cell’s contents safe, regulates the exchange of substances, and promotes communication between cells.
While omega-3s don’t construct the membrane, they integrate into its structure, helping to maintain its fluidity and flexibility. This is particularly important in tissues that require rapid and precise signaling, such as the brain and eyes.
Since our bodies cannot synthesize sufficient amounts of omega-3s on their own, we must obtain them from dietary sources or supplements.
How Are Fish Oil Supplements Made?
Following the catch, fish tissues are cooked and pressed to extract the oil. This crude oil undergoes purification and refining processes to eliminate contaminants, including heavy metals like copper, iron, and mercury.
During manufacturing, the oil may also be concentrated to enhance its EPA and DHA content.
Once purified, the oil is either encapsulated in soft gels or bottled as a liquid. Some supplements undergo additional treatment to eliminate odors or the characteristic “fishy” aftertaste.
Fish Oil and Heart Health
Omega-3 fatty acids are best known for their heart health benefits, with a particular focus on lowering triglyceride levels. Elevated triglycerides can increase the risk of heart disease.
A 2023 study analyzed 90 clinical trials involving over 72,000 participants and found a consistent relationship between dosage and effect. While higher doses often yielded greater improvements in heart health factors, it’s significant to note that “more is not always better.”
To achieve meaningful reductions in triglyceride levels (by 15 to 30%), a daily intake of over 2 grams of combined EPA and DHA is necessary. This is particularly crucial for individuals with preexisting heart conditions, elevated triglycerides, or obesity.
However, it’s essential to examine the label carefully. A typical “1,000 mg” fish oil capsule refers to the total weight of the oil, not necessarily the active omega-3 content. Most standard capsules contain approximately 300 mg of combined EPA and DHA, with the remainder being other fats.
At lower doses, changes in blood fat levels tend to be minimal. Notably, the same analysis indicated that low-dose fish oil may even slightly increase LDL or “bad” cholesterol while producing minimal effects on triglyceride levels.
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A 2018 trial evaluated a high-strength purified EPA product, administering 4 grams per day to individuals already on statins. Over five years, this regimen resulted in one major cardiovascular event (heart attack, stroke, or urgent procedure) being prevented for every 21 individuals treated. It’s worth noting that this was a prescription-only pharmaceutical-grade EPA, not a standard fish oil capsule.
In Australia, fish oil products can be found in pharmacies, health food stores, and supermarkets. Some concentrated formulas are designated as “practitioner-only” and are accessible through health professionals.
The same purified EPA used in the 2018 trial is now available in Australia as Vazkepa, a prescription medication. It was incorporated into the Pharmaceutical Benefits Scheme (PBS) in October 2024, increasing accessibility for high-risk patients.
For otherwise healthy individuals, the evidence supporting the use of standard fish oil supplements for preventing heart attacks or strokes is significantly weaker.
What About Arthritis and Joint Pain?
Fish oil exhibits mild anti-inflammatory properties.
In individuals with inflammatory arthritis, such as rheumatoid arthritis, omega-3s can alleviate joint tenderness and reduce morning stiffness.
To achieve these benefits, however, higher, consistent doses, typically around 2.7 grams of EPA and DHA per day, are necessary. This is roughly equivalent to consuming about nine standard 1,000 mg fish oil capsules daily for a minimum of eight to twelve weeks.
Can Fish Oil Improve Mood?
Some research indicates that omega-3s, particularly those rich in EPA, may modestly alleviate symptoms of clinical depression when used alongside antidepressants.
A 2019 review encompassing 26 trials with over 2,000 participants found a small overall benefit, especially for EPA-rich supplements at daily doses of up to approximately 1 gram. DHA-only formulations did not demonstrate clear benefits.
However, fish oil is not universally beneficial for mood enhancement. For individuals without a diagnosed depression, omega-3 supplements have not shown reliable effects in uplifting mood or preventing depressive symptoms.
How Much Can You Take?
For most individuals, fish oil is considered safe.
Common adverse effects include a fishy aftertaste, mild nausea, and diarrhea. Consuming capsules with food or opting for odorless or “de-fishified” products can mitigate these issues.
Prescription-strength products like Vazkepa (high-dose EPA) are generally well tolerated but may pose a slight increase in the risk of irregular heartbeat (atrial fibrillation) and bleeding.
The generally recommended safe upper limit for combined EPA and DHA from supplements is up to 3 grams per day for most adults.
For higher doses aimed at specific medical conditions, it is advisable to consult a healthcare professional.
So, Should You Take It?
The Heart Foundation suggests Australians consume two to three servings of oily fish weekly to achieve an intake of 250–500 mg of EPA and DHA per day.
If you don’t consume fish, a fish oil supplement (or algal oil for those who are vegetarian or vegan) can help fulfill your omega-3 requirements.
Individuals with heart disease (especially high triglycerides) or inflammatory arthritis may find additional benefits from fish oil. However, it’s important to consider dosage and product type, so consulting a health professional is recommended.
For most, the simplest, safest, and most nutritious way to obtain omega-3s remains through two or three servings of oily fish each week.
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