Quick summary
For most of European history, herring was valuable for a brutally simple reason: it fed people at scale. Long before the language of "functional foods", "bioactives" and "nutraceuticals", herring was one of the fish that helped build coastal trade, urban wealth, and everyday diets across the North Sea and Baltic worlds. Herring played a fundamental social and economic role in Europe, helped support cities such as Great Yarmouth, Amsterdam, and Copenhagen, and became known as the "silver of the sea".Today, old good herring is attracting fresh attention for a very different reason: its oil is unusually rich in cetoleic acid, an omega-11 long-chain monounsaturated fatty acid that is now being studied for superior effects on lipid metabolism, omega-3 biology, and cardiometabolic health.
Why herring has mattered in Western Europe for so long
Herring’s importance in Europe goes back well beyond the modern fishing industry. Ancient-DNA research highlighted by the University of Oslo suggests that long-distance herring trade was already established around 800 CE, several centuries earlier than many historians had assumed. By the medieval period, herring had become deeply tied to northern European commerce. Hanseatic trade networks moved herring caught off southern Sweden through Germany and as far south as the Alps. This was not just a fish on the menu. It was a strategic resource in edible form.
That old importance has not disappeared. Herring remains one of the most valuable commercial species in Europe. According to EUMOFA’s 2025 market report, EU exports of herring reached 224,949 tonnes in 2024, worth EUR 236 million.
Traditional herring products still matter
One reason herring lasted so long in European food culture is that it was endlessly adaptable. FAO’s herring processing guide notes that although some herring is sold whole or boned, most of the catch is processed before sale, with smoked, salted, marinated, and canned products forming the main outlets. That history still shows up in familiar products across Western and Northern Europe, from kippers and red herring to rollmops, Bismarck herring, pickled herring, and other marinated fillets.
Some of those traditions are formalized today. The EU commercial-names register for Clupea harengus lists Glückstädter Matjes as a protected geographical indication and Hollandse maatjesharing / Hollandse Nieuwe / Holländischer Matjes as a traditional speciality guaranteed.
There is another historical thread that feels oddly modern now. FAO notes that herring not suitable for human-food processing was historically cooked and pressed for oil, and that extracted herring oil was refined and widely used in margarine manufacture. For decades, the oil side of herring was mainly an industrial utility story. Nowadays, the new cetoleic-acid research suggests it may also be a high-value nutraceutical success.
What is cetoleic acid, and why is herring oil different?
Cetoleic acid is a 22-carbon long-chain monounsaturated fatty acid, usually written as C22:1 n-11 and commonly described as part of the omega-11 family. A 2026 review in Lipids in Health and Disease magazine notes that marine oils from herring are rich in long-chain monounsaturated fatty acids, especially cetoleic acid, and that in mammals cetoleic acid is essentially diet-derived, because mammal bodies do not meaningfully synthesize it themseves.
That review also points out something especially important for positioning herring in the supplement market: while anchovy and sardine oils are richer in EPA and DHA, capelin, herring, and mackerel oils tend to contain more long-chain MUFAs, and in herring oil cetoleic acid can reach as much as 22% of total fatty acids, depending in part on season. That gives herring oil a profile that is not simply “another fish oil, but slightly different.” It may represent a distinct marine-oil category with a different metabolic logic and effects. .
What current research is actually saying
One of the most cited turning points came in 2019, when researchers reported that cetoleic acid improved the efficiency of the n-3 fatty-acid metabolic pathway in Atlantic salmon and in human HepG2 liver cells. In simple terms, the study suggested cetoleic acid could help support conversion along the omega-3 pathway rather than just coexist beside omega-3s in the oil. That is the kind of finding that makes researchers pay attention, because it hints that the value of a marine oil may depend not only on how much EPA and DHA it contains, but on how it influences metabolism around them.
Human evidence is still early, but it is no longer nonexistent. In a 2024 paper in Prostaglandins, Leukotrienes and Essential Fatty Acids, researchers reported two placebo-controlled pilot studies using a cetoleic-rich oil. In one trial with 55 healthy volunteers, the omega-3 index increased about as much as would normally be expected from an oil with higher EPA and DHA levels. In another study with 28 female volunteers, the oil reduced skin erythema, a marker associated with inflammation. These were pilot studies, not final answers, but they moved cetoleic acid from theory into real human intervention data.
There is also a wider long-chain MUFA story around marine oils. A first-in-human trial published in 2020 found that saury oil, another fish oil rich in omega-11 long-chain monounsaturated fatty acids, was well tolerated and improved several lipid-related markers, including LDL particle counts, HDL particle size, and triglyceride-related measures. Saury is not herring, and pretending all fish oils are interchangeable is how bad health writing happens. Still, the result supports the broader idea that LC-MUFA-rich marine oils may have meaningful biological effects beyond the classic EPA-DHA narrative.
The strongest evidence so far is still preclinical
The most substantial evidence base remains in animal work, and that needs to be stated plainly because the supplement world loves skipping that sentence. A 2024 systematic review and meta-analysis in the British Journal of Nutrition found that cetoleic-acid-rich fish oils and concentrates significantly lowered circulating total cholesterol in rodent studies, with a mean difference of −0.65 mmol/L versus comparators. The authors concluded these ingredients should be further investigated as functional dietary components or supplements for cardiovascular-risk reduction. That is promising, but still preclinical.
Newer herring-specific studies add weight to that pattern. A 2024 British Journal of Nutrition paper reported that herring oil, but not anchovy oil, lowered cholesterol in a diabetic rat model. In 2025, a Frontiers in Nutrition study found that a herring oil rich in cetoleic acid lowered plasma lipids, including triglycerides and LDL, in rats and appeared to affect fatty-acid oxidation pathways. Then in 2026, another British Journal of Nutrition paper reported that herring oils containing cetoleic acid lowered serum cholesterol in obese Zucker rats. Taken together, those studies suggest herring oil is doing something metabolically distinctive, not merely acting like a weaker EPA-DHA product.
At the same time, not every result points in the same direction. A 2025 study on dietary herring oil found cetoleic acid was absorbed and accumulated in blood cells, liver, white adipose tissue, and muscle in a diabetic rat model, but did not increase EPA and DHA levels in those tissues in that experiment
Why cetoleic acid could change how marine oils are judged
For years, marine oil quality has mostly been discussed in terms of EPA and DHA concentration. That made sense, but it may turn out to be incomplete. Cetoleic-rich herring oil raises a more interesting question: what if the best marine oil is not simply the one with the highest omega-3 number on the label, but the one that most effectively improves blood markers, lipid metabolism, inflammatory balance, or the body’s handling of other fatty acids? Current studies do not prove that herring oil has already won that argument, but they do make it a serious contender in the next phase of supplement research.
That is why calling cetoleic-rich herring oil a future benchmark candidate is fair, while calling it the benchmark today would be premature. The 2026 review is explicit that knowledge of cetoleic acid’s health effects and mechanisms is still incomplete, but it also notes that by late 2025 multiple registered clinical trials were already investigating cetoleic acid or cetoleic-rich marine oils for health effects including skin function, general health, atherosclerosis, and LDL cholesterol. ClinicalTrials.gov also lists an adult study specifically examining the effect of herring oil concentrate on LDL cholesterol concentration. In other words, the field is no longer just speculating. It is building a pipeline.
Why herring is uniquely positioned
Herring has an advantage that many “future ingredients” do not: it already has history, scale, and consumer familiarity. Europe already knows how to catch it, process it, preserve it, and sell it. It already exists in mainstream food formats, protected traditional products, and industrial oil streams. So the emerging value of cetoleic acid does not require inventing a fish from scratch or persuading consumers to trust something they have never heard of. It requires revaluing a fish that Europe already knows, while adding a stronger biochemical explanation for why its oil may matter.
That makes herring unusually compelling from a content and market perspective. It carries historical weight, culinary legitimacy, and fresh scientific interest at the same time. Few ingredients get to say all three without sounding like marketing delirium. Herring can, provided the claims stay disciplined and the science is allowed to mature before people start pretending one pilot study has rewritten nutrition.
Conclusion
Herring first became important because it was useful: plentiful, tradable, preservable, and nourishing. Now it may be becoming important again for a more precise reason: its oil contains cetoleic acid, a marine fatty acid that appears increasingly relevant to lipid metabolism and the next generation of marine-oil research. The evidence is not complete, and the strongest data still come from preclinical work. But the direction is clear enough to matter. If larger human trials confirm what the current pilot studies and mechanistic research suggest, cetoleic-rich herring oil could become one of the most serious candidates for a new benchmark in marine oil supplements. That would give herring a rare double distinction: a fish that helped build Europe, and a fish that may still help reshape its nutrition industry.
