Episode 259 – 8 Things Worth Knowing About Omega-3s

Omega-3s are essential fatty acids, which means we need to get them through food or supplements. They play a role in several areas of health, but the details matter. The type of omega-3, the source, the dose, and the quality of the supplement can all change the outcome. This is not a full deep dive into every possible detail. Instead, it covers eight useful things worth knowing about omega-3s.

1. There are Different Types of Omega-3

The main types of omega-3 are ALA, EPA and DHA. ALA comes from plant-based sources. EPA and DHA come from marine sources, such as fish and algae.

Most of the health benefits are more strongly linked with EPA and DHA. The body can convert ALA into EPA and DHA, but it does this poorly. The conversion rate is usually under 10%. Because of this, fish and algae sources are often seen as better options when the goal is to increase EPA and DHA intake.

2. Omega-3 Comes From Both Animal and Plant Foods

Fatty fish are the main animal-based source of omega-3. Salmon, mackerel, sardines and herring are good examples. Other animal-based foods, such as oysters, mussels, liver and organ meats, can also contain smaller amounts. Plant-based sources include flaxseed, flaxseed oil, walnuts, chia seeds, hemp seeds and canola oil.

As a rough guide, 100g of salmon contains around 2g of omega-3 on average. Some plant-based sources, such as flaxseeds, can also contain around 1–2g per 100g. However, plant sources mostly provide ALA, so the conversion issue still matters.

3. Algae Can be a Useful Omega-3 Option

Algae is one of the original sources of omega-3 in the food chain. Fish accumulate omega-3 by eating algae or through the food chain, as smaller fish are eaten by larger fish. This matters because algae contains EPA and DHA directly. Its bioavailability is similar to fish, which makes it a useful option for people who do not eat fish. For people following a vegan diet, algae oil can help bypass fish-based foods or supplements while still providing EPA and DHA.

4. Omega-3 Status Can be Tested

Omega-3 status can be measured using an omega-3 index test. This looks at the percentage of fatty acids in red blood cells that are omega-3. The common categories are:

Low: less than 4%
Medium: 4–8%
High: greater than 8%

It is worth being a little cautious with these ranges because they can make it seem like higher is always better. There would likely be a point where more is not automatically better. Many people test low, including elite athletes. The omega-3 index can still be useful because red blood cells reflect dietary intake over roughly the past three to four months. This gives a more meaningful average picture than a single short-term measure.

5. Omega-3 Can Help Lower Triglycerides

Omega-3s have strong evidence for lowering triglycerides, particularly at higher doses. Higher levels of circulating EPA and DHA are linked with lower triglyceride levels and a reduced risk of cardiovascular events. However, the effect appears to depend on the dose. In people with moderate hypertriglyceridaemia, 3.4g of combined EPA and DHA lowered triglycerides significantly. A smaller dose of 0.85g did not make a statistically significant difference.

Another example involved people who had already had a cardiovascular event and were taking statins. A high dose of EPA reduced secondary cardiovascular events. This is a more specific situation, but it shows that omega-3s can have clear uses in certain contexts.

6. Omega-3 May Help With Inflammation and Joint Pain

Omega-3s may help reduce pain because of their role in lowering inflammation. A 2025 meta-analysis looked at 41 randomised controlled trials and included 3,800 participants across several conditions. Omega-3 fatty acids showed a moderate but statistically significant reduction in pain intensity at one and two months.

This was seen in conditions such as rheumatoid arthritis, migraines and mixed chronic pain. However, the effect was not as clear for osteoarthritis. The doses in this area were usually around 1-3g per day.

7. Omega-3 May Support Mental Health and Cognition

Omega-3 is linked with better mental health and improved cognitive function. That does not mean omega-3 is a magic fix. Mental health has many moving parts, and omega-3 is only one factor. Still, it can be a useful bonus when the rest of the diet and lifestyle are also taken into account.

8. Supplements Can Help, but Quality Matters

Fish oil and algae oil are the main supplement options. For general supplementation, it makes sense to look for a combined EPA and DHA intake of around 500–1000mg. This may come from around 1-3g of fish oil, depending on the product. Triple-strength fish oil can make this easier because it usually provides more EPA and DHA per capsule. Some products do this by reducing the amount of marine triglycerides, while others use a larger capsule.

One issue with omega-3 supplements is oxidation. Some independent testing has found that a portion of omega-3 supplements are already oxidised by the time people buy them. This appears to have improved over the last decade, but it still matters. To reduce the risk, choose reputable brands, avoid using products past their expiry date, and store them in a cool environment. Smaller containers may also help if you are unlikely to finish a large tub quickly. Some products that contain vitamin E may also last longer.

How to Get Enough Omega-3 Through Food

For people who eat fish, two to three serves of fatty fish per week can usually cover baseline omega-3 intake. For example, if 100g of salmon provides around 2g of omega-3, then a 150–200g serve can provide a solid amount. Having fatty fish a few times per week can create an intake similar to supplementing.

People following plant-based diets can still get omega-3 from foods like flaxseeds, chia seeds, walnuts, hemp seeds and canola oil. However, these mostly provide ALA, which the body does not convert well into EPA and DHA. In that case, algae oil supplementation can make sense.

Final Thoughts

Omega-3 can be an easy win for many people. It may support heart health, inflammation, joint pain, mental health and cognition. Food can cover the basics for people who eat fatty fish regularly. However, supplementation can be a practical option, especially when fatty fish feels too expensive or is not part of someone’s usual diet. The main goal is to address omega-3 intake in a way that feels realistic, consistent and suitable for the individual.