omega-3 supplements levels in fish, shellfish and marine algae fall as seawater warms, according to a global meta-analysis published in Global Change Biology on 19 August 2026. Researchers led from Adelaide University pooled 489 controlled experiments drawn from 143 published papers and covering 132 marine species, then measured how warming and ocean acidification changed the fatty acid composition of those organisms. Across the dataset the proportion of omega-3 fatty acids declined by up to 34 per cent under warming, while saturated fats rose by up to 22 per cent. The largest falls were in primary producers such as algae, which sit at the base of the marine food web. Writing in The Conversation on 24 August, three of the authors said that under the most extreme scenario tested, more than 10C above baseline, omega-3 content fell by 50 per cent in fish, 51 per cent in invertebrates and 34 per cent in algae. Acidification had only a minor overall effect.
A laboratory result, not a measurement of the wild food chain
The authors are explicit about the limits. Every study in the pool was a controlled experiment rather than an observation of wild populations, so the analysis cannot capture how multiple stressors interact in real oceans. Most experiments ran for less than a month, which says little about whether species adapt over generations. The paper also flags data gaps on absolute fatty acid concentrations, on acidification, and on tropical fish. The work was funded by the Australian Research Council under grants DP230101932 and FT200100870. For scale, the 50 per cent figure comes from warming far beyond the roughly 0.6C rise in ocean temperature the authors record since 1980.
What this means for your supplement routine
Nothing in the paper describes a change to seafood or to fish oil products on sale today. It models what happens to marine organisms held in tanks at temperatures well above current conditions. It did not test any commercial product, measure any human outcome, or compare wild-caught with farmed sources. EPA and DHA contribute to the normal function of the heart, which is the wording authorised on the GB Nutrition and Health Claims Register at that register's conditions of use, and this analysis does not alter that position. For anyone buying regularly across the full Perqen catalogue, the question this month is still what things cost rather than what the oceans will look like in 2100.
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This article reports published news and research and is for information only. Food supplements are not a substitute for a varied diet or medical care, and no product mentioned is intended to diagnose, treat, cure or prevent any disease. Speak to your GP or pharmacist before changing what you take, especially if you are pregnant, breastfeeding, or taking prescribed medicines.