What is the best thing to combine omega-3 fatty acids with?

Omega-3 fatty acids are among the best-understood fatty components of the diet. The impetus for research into them came from a 1971 scientific paper on the blood lipid profile of residents of western Greenland. In addition to analysing blood samples, the researchers also examined the fatty acid composition of the local population’s diet, ultimately drawing attention to long-chain omega-3 fatty acids, which are characteristic of seafood. It is now understood not only how they work, but also which substances they co-occur with and interact with.

1. The structure of omega-3 fatty acids
2. Sources of omega-3 fatty acids
3. Combining omega-3 fatty acids
4. FAQ – Frequently Asked Questions

The structure of omega-3 fatty acids

Omega-3 fatty acids are a group of polyunsaturated fatty acids whose molecules contain several double bonds, which influence their structure and properties. The name ‘omega-3’ derives from their chemical structure: the first such bond is located at the third carbon atom, counting from one end of the molecule.

The most important of these are alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA is an essential fatty acid, as the human body cannot produce it itself and must obtain it from the diet. EPA and DHA have longer molecules and are referred to as long-chain omega-3 fatty acids. The body can convert some ALA into EPA and then into DHA, but this process is not very efficient.

EPA and DHA are components of the fats that make up cell membranes. DHA is found in particularly high concentrations in the tissues of the nervous system and the retina of the eye, whilst EPA and DHA can also be used to produce various lipid compounds involved in regulating bodily processes.

Sources of omega-3 fatty acids

The richest natural sources of EPA and DHA are oily sea fish, including salmon, herring, mackerel and sardines. Leaner fish and some other seafood contain smaller amounts of these acids. Interestingly, microalgae are the primary source of long-chain omega-3s in the marine environment. Fish accumulate EPA and DHA by eating organisms lower down the food chain; therefore, microalgae oil can be a direct source of DHA. ALA is found primarily in plant-based products. It is abundant in linseed and linseed oil, chia seeds, walnuts, as well as rapeseed and soya oil.

Fish oil, krill oil or microalgae oil are most commonly used in supplements. Cod liver oil also provides vitamins A and D, so it should not be regarded solely as a source of omega-3. When choosing a supplement, the amount of EPA and DHA stated on the label is more important than the sheer volume of oil in the capsule. A capsule containing 1,000 mg of fish oil does not necessarily contain 1,000 mg of EPA and DHA, as part of its content consists of other fatty acids.

Links to omega-3

Combining omega-3 fatty acids

Omega-3 fatty acids are best taken with a meal, particularly one that contains some fat. This applies especially to supplements containing EPA and DHA in the form of ethyl esters, the absorption of which may be greater when taken with a meal than on an empty stomach. The supplement can therefore be taken with lunch or dinner containing olive oil, vegetable oil, avocado, nuts, eggs, fish or another source of fat.

It is not necessary to combine omega-3 fatty acids with a specific vitamin or other dietary component in order to achieve their basic effects. Omega-3 supplements are often combined with vitamin D; however, each of these components performs different functions and should be used in accordance with individual requirements. Products containing fish oils may also contain vitamin E, which primarily acts as an antioxidant and helps to limit the oxidation of the fatty acids in the supplement.

Omega-3 can also be combined with other fat-soluble ingredients, such as astaxanthin. This is a carotenoid found naturally in microalgae and marine organisms, amongst others. Another interesting ingredient is choline, which plays a role in the body’s lipid metabolism and in the formation of phosphatidylcholine – an important component of cell membranes and one of the elements involved in the transport of DHA.

"Omega-3 fatty acids do not require a complex combination of supplements. The simplest rule is to take the supplement with a meal containing fat. Vitamin D, astaxanthin or choline may be present alongside omega-3, but they are not essential for EPA and DHA to fulfil their basic functions." Anna Zięba – Dietitian

FAQ – Frequently Asked Questions

What is the best way to take omega-3s?

The simplest way is to take them with a meal containing fat, such as lunch or dinner. This could be a meal containing olive oil, eggs, fish, avocado, nuts or another source of fat.

Can omega-3 be taken on an empty stomach?

Yes, but this isn’t always the best option. For some forms of EPA and DHA, particularly ethyl esters, taking the supplement with a meal can improve their absorption.

Do you need to combine omega-3 with vitamin D?

No. There is no need to combine omega-3 with vitamin D. Both can be taken together, but they perform different functions in the body. The need for vitamin D supplementation should be decided on a case-by-case basis.

Why is vitamin E included in omega-3 supplements?

Vitamin E is an antioxidant. In preparations containing oils, it may help to limit the oxidation of polyunsaturated fatty acids. However, its presence in the formulation does not mean that everyone taking omega-3 needs to take an additional vitamin E supplement.

Can omega-3 be taken alongside astaxanthin?

Yes. Astaxanthin is a fat-soluble carotenoid and can be taken alongside omega-3. However, it is not an essential component for the action of EPA and DHA.

Can omega-3 be taken alongside choline?

Yes. Choline plays a role in lipid metabolism and in the formation of phosphatidylcholine, an important component of cell membranes. However, this does not mean that omega-3 must always be supplemented alongside choline.

Is the amount of fish oil more important than the levels of EPA and DHA?

When choosing a supplement, look first and foremost at the amount of EPA and DHA in the daily dose. The statement ‘1,000 mg of fish oil’ does not automatically mean 1,000 mg of EPA and DHA.

Can microalgae oil replace fish oil?

Microalgae oil can be a source of long-chain omega-3 fatty acids and is a particularly useful option for people who do not eat fish. It is worth checking the label to see exactly how much DHA – and, in some products, EPA – a single serving provides.

When is the best time to take omega-3 – in the morning or in the evening?

The time of day is less important than taking the supplement regularly and with a suitable meal. You can therefore choose breakfast, lunch or dinner – depending on when it is easiest for you to remember to take your supplement.

Sources:

• Saini, R. K., & Keum, Y. S. (2018). Omega-3 and omega-6 polyunsaturated fatty acids: Dietary sources, metabolism, and significance - A review. Life sciences, 203, 255–267. https://doi.org/10.1016/j.lfs.2018.04.049
• Baker, E. J., Miles, E. A., Burdge, G. C., Yaqoob, P., & Calder, P. C. (2016). Metabolism and functional effects of plant-derived omega-3 fatty acids in humans. Progress in lipid research, 64, 30–56. https://doi.org/10.1016/j.plipres.2016.07.002
• Alijani, S., Hahn, A., Harris, W. S., & Schuchardt, J. P. (2025). Bioavailability of EPA and DHA in humans - A comprehensive review. Progress in lipid research, 97, 101318. https://doi.org/10.1016/j.plipres.2024.101318