The Best Fish Oil Brands Available in the UK

Fish oil is one of the most researched supplements, particularly for its omega-3 fatty acids EPA and DHA. On a ketogenic diet, where fatty fish may not always be daily staples, a quality fish oil can help maintain adequate intake of these essential fats. The UK market offers several reputable brands, but not all products are equal in purity or potency.

What to look for in a fish oil supplement

Concentration matters. A 1,000 mg capsule might contain only 300 mg of combined EPA and DHA—the active components. Higher concentrations mean fewer capsules for the same dose. Look for at least 500 mg combined EPA and DHA per 1,000 mg of oil.

Molecular form also affects absorption. Triglyceride (TG) and re-esterified triglyceride (rTG) forms are better utilised by the body than ethyl ester (EE) forms, though the latter are cheaper. omega-3 testing methods can verify label claims.

Top UK fish oil brands

1. Nordic Naturals Ultimate Omega – rTG form, 650 mg EPA/DHA per softgel. Sold at Holland & Barrett for £34.50 per 60-count bottle. 2. Seven Seas Pure Gold High Strength – TG form, 504 mg EPA/DHA per capsule. Available at Boots for £15 (120 capsules). 3. Myprotein Omega-3 – Ethyl ester form but third-party tested. 330 mg EPA/DHA per softgel. Priced at £9.99 for 180 capsules. 4. Solgar Omega-3 950 mg – TG form, 504 mg EPA/DHA. Sold at Amazon UK for £28.99 (120 capsules).

What this means in practice

For someone eating keto in the UK, fish oil can offset the lack of fatty fish like mackerel or salmon during colder months when fresh seafood is less appealing. At Tesco, a 200 g portion of fresh salmon costs around £3.50, while a month’s supply of Nordic Naturals works out to roughly £1.15 per day for an equivalent EPA/DHA dose.

Storing fish oil in the fridge prevents oxidation, especially important in British kitchens where central heating can fluctuate. Those who dislike capsules can opt for liquid forms like Bare Biology’s Lion Heart, though these cost nearer £40 per bottle.

Frequently asked questions

Is cod liver oil the same as fish oil? No. Cod liver oil contains vitamins A and D in addition to omega-3s. While beneficial, these vitamins can accumulate to excess if taken alongside other supplements.

Can fish oil support ketosis? Omega-3s don’t directly induce ketosis but may help manage inflammation associated with the keto adaptation timeline. A 2013 study in the British Journal of Nutrition found anti-inflammatory effects from omega-3s during low-carb diets.

How much fish oil should I take daily? Most studies use 1,000–2,000 mg combined EPA/DHA daily. The NHS suggests up to 5 g total omega-3s per day from supplements, but consult your GP if on blood-thinning medications.

The bottom line

Quality fish oil supplements provide concentrated EPA and DHA without the mercury risk of frequent seafood consumption. Nordic Naturals and Seven Seas lead for purity, while budget options like Myprotein suit those prioritising cost. If you’d rather not do the macro maths yourself, the Keto Dieting app does it for you on Google Play and the App Store.

Educational only — not medical advice. This article is for general information. Speak to your GP before changing your diet, especially if you have type 1 or type 2 diabetes, kidney or liver disease, are pregnant or breastfeeding, or take medication for blood pressure, cholesterol, or blood glucose.

References

Bueno NB, de Melo IS, de Oliveira SL, da Rocha Ataide T (2013). Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. British Journal of Nutrition. https://doi.org/10.1017/S0007114513000548