Category: Krill Oil 101

The basics, done properly: what astaxanthin is, why phospholipids matter, how krill oil compares to fish oil, how to store it, when to expect results, and how ours is actually made — from a boat, not a factory. Start here if you’re new to krill oil, or if you want the real mechanism behind the marketing. Plain-English fundamentals from Captains Krill Oil.

Does Krill Oil Expire? What “Rancid” Actually Means in an Omega-3 Bottle

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Yes, krill oil expires — but not the way milk expires, and not always the way the printed date on the bottle suggests. The date stamped on the box is a manufacturer’s best-guess about when the oil will still meet its label claims under reasonable storage. The thing you actually care about is something the date can’t tell you: whether the oil inside has gone rancid. Those are two different questions, and the gap between them is where most of the confusion lives.

Here’s the honest short version. Omega-3 oils — krill, fish, algae, all of them — are chemically fragile. The same thing that makes them good for you, all those reactive double bonds in the EPA and DHA, also makes them eager to react with oxygen. When they do, the oil oxidizes. Past a certain point we call that rancid. A rancid omega-3 isn’t just less effective; the oxidation products it carries may actively work against the reason you took it in the first place. So the real question isn’t “what’s the expiration date” — it’s “how do I know if this oil is fresh, and how do I keep it that way.” And the good news is you already own the two tools that answer it: your eyes and your nose.

What “rancid” actually means at the molecular level

Rancidity is just oxidation that’s gone far enough to notice. It happens in two stages, and the distinction matters because it’s the reason your nose works as well as it does.

In the first stage, oxygen attacks those fragile double bonds and forms compounds called peroxides. This is primary oxidation. Peroxides themselves are mostly tasteless and odorless. But they’re unstable, and they break down into the second wave: the aldehydes and ketones of secondary oxidation. These are the molecules you actually smell and taste — the “off,” fishy, paint-thinner note of an oil that’s turned (Global Organization for EPA and DHA Omega-3, “Oxidation in Omega-3 Oils: An Overview”). So when someone says an oil is “rancid,” they usually mean secondary oxidation has produced enough of those compounds to taste or smell. Your senses are tuned to exactly the stage that matters.

The market really does have a freshness problem

This isn’t us being dramatic. Independent testing has repeatedly found that a startling share of omega-3 supplements on shelves are already oxidized by the time you buy them, with results varying widely by formulation and delivery form (Jackowski et al., Journal of Nutritional Science, 2015; George Washington University School of Medicine, “Tests Find Many Popular Omega-3 Supplements Are Rancid”). The debate over exactly how bad it is, and how much it matters for health, is still live among researchers (NutraIngredients, “Fish oil oxidation: experts debate the science and health impacts,” December 2025).

Now here’s where I’ll part ways with a lot of the industry. The standard answer to “how fresh is it” is a lab score called TOTOX — total oxidation, built from those peroxide and anisidine measurements. And TOTOX is a real number. But I’ll be straight with you about why we don’t build our pitch around it. It’s an expensive test. Its accuracy and relevance to a sealed, finished softgel are more debatable than the marketing lets on — a single TOTOX figure on a spec sheet is a snapshot of one sample at one moment, not a guarantee of what’s in the capsule in your hand. And almost no brand prints it for you anyway. So you can chase a lab number that’s costly, contestable, and usually hidden — or you can do what fishermen have always done and use your senses. We think the senses win.

The honest caveat I owe you: the science on what oxidized omega-3 does to a human being is genuinely unsettled. The flavor and potency loss is not in dispute — a rancid oil tastes bad and delivers less intact EPA and DHA. Whether the byproducts cause measurable harm at the doses people swallow is the harder question, and nobody has run the long, clean human trial that would settle it. So I won’t tell you rancid fish oil will hurt you. I’ll tell you it’s a waste of money and possibly counterproductive, and that “fresh or don’t bother” is the only sane policy.

Krill oil’s twist: astaxanthin is a real bodyguard — and your color gauge

Krill oil has a feature fish oil doesn’t, and it happens to be the reason the eyeball test works so well. Antarctic krill oil naturally contains astaxanthin, the red carotenoid that gives the oil its deep color and acts as a built-in antioxidant — a bodyguard standing between the omega-3s and the oxygen. This is real, and it’s one reason krill oil can be more oxidatively stable than an unprotected fish oil.

But “more stable” is not “immune.” Recent storage research on Antarctic krill oil shows that the astaxanthin, the tocopherol, and the intact phospholipids steadily decline as the oil ages, with oxidation products rising in their place (Springer, European Food Research and Technology, 2025; ScienceDirect, “Lipid oxidation mechanisms of Antarctic krill oil during storage,” 2025). Here’s why that’s useful to you: as the bodyguard gets spent, the color fades. A krill oil that has lost its deep red has likely burned through most of its protection. The pigment isn’t just marketing — it’s a gauge you can read with your own eyes.

So how long does it actually last — and what does the date mean?

For a properly made, properly packaged krill oil, an unopened shelf life of about two years is typical, and that’s roughly what the printed date reflects. Encouragingly, most of an oil’s oxidation tends to happen before you ever get it — during raw-material handling, processing, and encapsulation. Once the oil is sealed inside a softgel with its antioxidants intact and boxed away from light, a good product holds up well. The capsule shell is itself an oxygen barrier, which is part of why softgels generally outlast bottled liquid oil you reopen daily.

That last point is the practical key. The date assumes sensible storage. It does not survive a sunny windowsill, a car in July, or the cabinet above the stove. Heat and light tear through the astaxanthin and accelerate everything — an oil with eighteen months left on the date can be functionally rancid in a few hot weeks. The date is a proxy for freshness under good conditions; how you store it is what makes the proxy true or false.

How to tell if yours has turned — no lab required

You don’t need a test. You need the two senses you brought with you.

Start with color. Fresh krill oil is a deep, confident red — that’s the astaxanthin doing its job. An oil that’s faded toward pale orange or brown has likely spent most of its antioxidant protection. Color is the cheapest freshness test there is, and for krill oil specifically it’s a genuinely good one.

Then the nose. Break one capsule open. A fresh krill oil smells faintly of the sea — clean, mild, a little shellfish. A rancid one smells sharp, sour, paint-like, or aggressively fishy in the bad way. Taste confirms it: fresh is neutral to mildly marine, rancid is bitter and lingering. And if a supplement is giving you fishy burps or a touch of nausea — symptoms people often blame on omega-3s as a category — oxidation is a common culprit rather than the oil itself (InnovixLabs, “Oxidized & Rancid Fish Oil”). Deep red and clean as the sea? It’s good. Faded or sharp? Toss it — ours or anyone’s.

How to keep it fresh: cool, dark, dry, sealed — not the fridge

Keeping omega-3 fresh comes down to denying oxidation its inputs, and there’s one piece of common advice we flatly disagree with: don’t refrigerate it.

It sounds responsible, but the fridge works against you in two ways. First, it’s a humid environment, and moisture is no friend to a softgel. Second — and this is the one that actually ruins bottles — it’s easy to freeze a krill oil by mistake in a cold fridge or a freezer door. A frozen softgel can split, and once the shell fails and air reaches the oil, it oxidizes fast. You took the one thing protecting the oil, the sealed capsule, and broke it.

So skip the fridge. Keep it cool (stable room temperature, away from the stove and any heat source), dark (leave it in its opaque box or a cupboard, not on the counter), dry, and sealed (close it tightly; don’t decant a month’s supply into a daily pill organizer where each capsule sits exposed to air and light). And buy a quantity you’ll finish within a few months rather than the bulk jar that saves a few dollars and then slowly oxidizes on your shelf.

A note on Captains

We get this question a lot, usually phrased as worry: is my krill oil still good? The reason we can answer it plainly is that we don’t hide behind a lab number we hope you won’t understand. We tell you to use your eyes and your nose, because on this particular product they genuinely tell you what you need to know: deep red and clean means the astaxanthin is still on the job; faded or sharp means it’s done. Our oil is mechanically extracted with no chemical solvents at any stage, and the astaxanthin in it is the krill’s own, not something dripped in afterward — which is exactly why the color is worth trusting. Store it cool, dark, and dry, keep it out of the fridge, finish it within a few months of opening, and if it ever smells like a tackle box, throw it out. Honest answer, not a pitch. — captainskrilloil.com

Same Molecule, Different Vehicle: Phospholipid vs. Triglyceride Omega-3s

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Here’s the honest version of this article up front: if you’re already taking a fish oil supplement and tolerating it fine and taking it every day, the form of omega-3 you’re getting probably doesn’t matter enough to switch. The intake is the point. The form is a detail.

But if you’ve tried fish oil and quit — because of the burps, the reflux, the lingering taste, or just the size of the capsule — the form might be exactly the reason you quit. And that makes it worth understanding.

This is an explainer on the three main molecular forms omega-3 supplements come in, what the absorption research actually shows, and when the difference matters enough to care about.

Three Forms, One Fatty Acid

EPA and DHA — the two omega-3 fatty acids your body actually uses — are the same molecules regardless of how they’re packaged. The difference between supplements is the vehicle those molecules ride in from your gut into your bloodstream. There are three common ones:

Ethyl esters (EE). The cheapest form. Created during the concentration process when omega-3s are chemically bonded to ethanol. This is what most bargain-shelf fish oil capsules contain. Your body has to strip the ethanol bond before it can absorb the EPA and DHA, which makes it the slowest and least efficient form. Ethyl esters also depend heavily on dietary fat for absorption — take them on an empty stomach and you lose a significant chunk of the dose.

Triglycerides (TG). The natural form found in fish tissue. Three fatty acid chains attached to a glycerol backbone. Your pancreatic lipase knows exactly what to do with this structure — it’s the same form you’d get from eating salmon. Better absorbed than ethyl esters, and the form used in most mid-to-premium fish oil products. Re-esterified triglycerides (rTG) are a concentrated version that tests at the top of the bioavailability charts alongside phospholipids.

Phospholipids (PL). The form found in krill. Instead of three fatty acid chains on a glycerol backbone, you get two fatty acid chains plus a phosphate head group — the same architecture your own cell membranes use. This structural similarity means phospholipid omega-3s integrate into micelles more readily in the gut and don’t require the same enzymatic processing as triglycerides or ethyl esters before absorption (Pham et al., 2024). About 60–70% of the omega-3s in krill oil are bound to phospholipids, with phosphatidylcholine being the dominant carrier.

What the Absorption Studies Actually Show

The bioavailability question has been studied enough times that a rough hierarchy has emerged. The 2025 consensus, drawn from studies published between 2018 and 2024, ranks the forms: rTG ≈ PL > TG > EE. Re-esterified triglycerides and phospholipids sit at the top, natural triglycerides in the middle, ethyl esters at the bottom (MVS Pharma, 2024 review).

A 2024 network meta-analysis — the most comprehensive comparison to date — pooled data across multiple dosage levels and molecular forms. At doses below 2,000 mg (which covers most consumer supplements), krill oil’s phospholipid form showed enhanced area-under-the-curve plasma levels compared to standard fish oil triglycerides (Clinical Nutrition ESPEN, 2024). The advantage was most pronounced at low doses — exactly the range where most people are actually supplementing.

A 2023 randomized, double-blind crossover study compared phospholipid-enhanced fish oil against krill oil directly. The absorption totals were similar, but the profiles differed: the phospholipid forms showed higher, earlier plasma peaks, meaning the omega-3s reached the bloodstream faster (PubMed, 2023).

I want to be careful here. “Better absorbed” is not the same thing as “better for your health.” A 2024 meta-analysis of 64 randomized controlled trials found no significant difference in triglyceride, LDL, HDL, or total cholesterol levels between krill oil and fish oil. The absorption advantage doesn’t always translate into measurably different clinical outcomes — at least not in the endpoints that have been studied so far.

That said, one newer trial pushes back on that conclusion slightly. A 2026 pilot RCT in BMC Complementary Medicine and Therapies randomized 47 patients with hypertriglyceridemia to phospholipid-bound omega-3s (825 mg/day EPA+DHA) or standard omega-3s (903 mg/day EPA+DHA) for 12 weeks. The phospholipid group’s mean triglycerides dropped 9.1 mg/dL; the standard group’s rose 15.2 mg/dL. More notably, 36.4% of the phospholipid group hit the ≤150 mg/dL target versus 13.6% in the standard group (PMC, 2026). It’s a small, pilot study — not proof. But the direction is interesting, and it’s the first head-to-head clinical outcomes trial between the two forms.

The Omega-3 Index Difference

The omega-3 index — the percentage of EPA and DHA in your red blood cell membranes — is arguably a better measure of whether the omega-3s you’re swallowing are actually making it into your cells. The target is 8% or higher. Most Americans sit at 4–5%.

A controlled crossover trial gave 24 healthy volunteers either krill oil or fish oil, each providing 600 mg of omega-3s, for four weeks with washout periods between. Krill oil raised the omega-3 index more than fish oil at the same dose. EPA levels in red blood cells were significantly higher after the krill oil phase. DHA rose compared to control in the krill oil group but didn’t reach significance in the fish oil group (Ramprasath et al., Lipids in Health and Disease, 2013).

An earlier comparative bioavailability study found the same pattern: the highest incorporation of EPA and DHA into plasma phospholipids came from krill oil, followed by re-esterified triglyceride fish oil, then ethyl ester fish oil (Schuchardt et al., 2011).

What this means practically: milligram for milligram, more of the EPA and DHA from phospholipid-bound omega-3s ends up in your cell membranes, where it does its work. A smaller dose of the phospholipid form can move the needle on your omega-3 index as much as a larger dose of triglyceride fish oil.

Why the Form Affects Whether You Actually Take It

This is the part that matters more than any bioavailability chart.

“Fish burps” are the single most cited reason people stop taking fish oil. The mechanism is straightforward: triglyceride oil doesn’t mix with water. It floats on top of your stomach contents. If you get any reflux — and a lot of people do — what comes up tastes like fish. The larger the capsule, the worse the problem, and standard fish oil capsules are not small.

Phospholipids behave differently in the stomach. They’re amphiphilic — one end dissolves in water, the other in fat — which means they emulsify in stomach fluid rather than pooling on top of it. This is the same reason egg yolks emulsify a vinaigrette: the phospholipids in the yolk bridge the oil and water. In practice, this means krill oil supplements are far less likely to repeat on you, and the capsules are typically smaller because the dose doesn’t need to be as large to deliver the same amount of usable EPA and DHA.

For most healthy adults, this is a comfort-of-use difference. Annoying but manageable. But for people with GI sensitivity, people on GLP-1 medications (where nausea and reflux are already daily features), or anyone who has quietly stopped taking fish oil because the experience was unpleasant — this is the difference between a supplement they take and a supplement that sits in the cabinet.

Consistency beats potency. A 500 mg dose you take every day will always outperform a 2,000 mg dose you take when you remember, which will always outperform a 3,000 mg dose you bought once, tried twice, and abandoned.

Astaxanthin: The Bonus You Didn’t Ask About

Krill oil is red. That color comes from astaxanthin, a carotenoid antioxidant that krill accumulate from the microalgae they eat. It’s not added during manufacturing — it’s part of the animal.

Astaxanthin does two practical things in the context of an omega-3 supplement. First, it protects the omega-3 fatty acids themselves from oxidation. Omega-3s are polyunsaturated, which means they have multiple double bonds in their carbon chain — and each one is a site where oxygen can attack the molecule and turn it rancid. Fish oil manufacturers add synthetic antioxidants (usually tocopherols) to slow this down. Krill oil comes with its own antioxidant already built in (Marine Drugs, 2021).

Second, astaxanthin has its own modest evidence base as an anti-inflammatory and antioxidant in human tissue — separate from whatever it does for the oil in the capsule. I wouldn’t buy a supplement for astaxanthin alone, but getting it included in your omega-3 isn’t nothing.

Where the Form Doesn’t Matter

If you eat fatty fish twice a week — real fatty fish, not tilapia — you probably don’t need to think about any of this. Salmon, sardines, mackerel, and anchovies deliver omega-3s in their natural triglyceride form, packaged with the fats and proteins your digestive system evolved to handle. No supplement form will beat that.

If you’re taking a high-quality re-esterified triglyceride fish oil and tolerating it well, your absorption is already near the top of the hierarchy. Switching to krill oil would give you a slightly different absorption profile and smaller capsules, but the practical difference in outcomes is unlikely to be meaningful. Don’t fix what isn’t broken.

If cost is the primary constraint, a standard triglyceride fish oil taken consistently with a meal containing some fat will get the job done. It won’t absorb as efficiently as rTG or phospholipid forms, but the gap narrows when you take it with food, and the most important variable is still whether you take it at all.

Where It Does Matter

The form starts to matter when tolerability is the bottleneck — when you’ve tried fish oil and the experience was bad enough that you stopped. It matters when the dose needs to be small because appetite is low, stomach space is limited, or nausea is already part of the picture. It matters when you want to move the omega-3 index with the minimum effective dose rather than swallowing four large capsules a day.

It matters, in other words, for exactly the people who are most likely to be under-supplemented: the ones who tried and quit.

Captains Krill Oil™ is one option in this space. We make an honest, small-batch phospholipid omega-3 product — always have. But the more important thing than which brand you pick is that you’re getting EPA and DHA from somewhere, in a form you’ll actually take, at a dose that moves your number. The molecule is the point. The vehicle is just how it gets there.

If you want to know where you stand, the omega-3 index test costs about $50 and gives you a real number. Target is 8% or higher. That number matters more than which bottle is on your shelf.

Is Krill Oil Extracted With Hexane? What’s Actually in the Bottle

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If you’ve fallen down a late-night supplement rabbit hole and ended up on the question of how krill oil is made — congratulations, you’re asking the question almost no krill oil website wants to answer directly. The labels say things like “pure,” “premium,” “Antarctic-sourced,” and a great many of them say nothing at all about how the oil got out of the krill and into the capsule. The implication is that you don’t need to know. You do, a little. Because the way krill oil is extracted determines what residues might tag along, how much of the good stuff (phospholipids, astaxanthin, omega-3s) survives the process, and how rancid the oil is by the time you swallow it. The short, honest answer is: most premium krill oil sold in 2026 is not extracted with hexane. The longer answer involves a small zoo of extraction methods, a 2024 European safety re-evaluation, and a label term — “solvent-free” — that means something more specific than it sounds. Here’s the whole picture, from the boat down.

How krill oil is actually extracted (and why it matters)

Krill are tiny. About the size of a paperclip, and roughly 80% water by weight. To turn a trawler-load of fresh Antarctic krill into a teaspoon of dark-red oil, you have to separate the lipids (the oil) from everything else — protein, water, chitin shells, minerals. That separation is the extraction step, and the industry uses several different approaches. The traditional method, going back decades, is a two-step solvent extraction with acetone followed by ethanol. Acetone pulls out the neutral lipids (the triglycerides), and ethanol pulls out the polar lipids (the phospholipids — the part of krill oil that gives it its bioavailability edge). Both solvents are then evaporated off, and what’s left is krill oil. It works, but it’s laborious, and acetone in particular is unpopular with cleaner-label brands. Most modern premium krill oil is extracted using ethanol alone, sometimes combined with low-temperature fractionation to separate the phospholipid-enriched fraction from the neutral oil. Aker BioMarine’s Flexitech process — which produces Superba 2 and Superba Boost, two of the most-sold krill oil ingredients on the planet — uses only ethanol and relies on low temperature and efficient fractionation methods, with no high-temperature molecular distillation and no other solvents. Rimfrost, the other major krill oil producer, holds a family of patents on a solvent-free process that cooks fresh krill at around 90°C, then separates the oil mechanically with a decanter and screw press — no chemical solvents at any stage. A 2019 head-to-head comparison published in Food Science & Nutrition tested extraction efficiency across the main methods and found this order, from least to most efficient at pulling lipids from krill meal: n-hexane (69.5%) < supercritical CO₂ (71.2%) < subcritical n-butane (82.6%) < ethanol (93.6%) < subcritical dimethyl ether (93.8%). Hexane, in other words, is actually the worst solvent for getting oil out of krill. It’s near the bottom of every modern industrial extraction process for this particular raw material. There’s a reason no major krill oil brand markets itself on hexane extraction: nobody uses it as a primary solvent for krill, because it doesn’t work as well as ethanol. That doesn’t mean hexane is never anywhere near the supply chain. It’s still common in vegetable oil extraction, in some fish oil refining processes, and as a processing aid in concentrated omega-3 products. But for krill oil specifically, hexane is mostly a research-paper benchmark, not a production tool.

The 2024 EFSA re-evaluation: what changed, and what didn’t

The reason hexane is on anyone’s radar right now is a quietly important regulatory moment. In 2024, the European Food Safety Authority published a technical report on the need to re-evaluate the safety of technical hexane as an extraction solvent in food. The headline finding was not “hexane is unsafe.” It was “we don’t actually have enough data to confidently say it’s safe at modern exposure levels, especially for infants and young children.” A few specifics worth knowing. Technical hexane is not a single chemical — it’s a mixture of n-hexane and related compounds whose impurities are poorly specified in current regulatory frameworks. Human absorption of n-hexane is well documented. And the exposure assessment models in use since the 1990s may have underestimated how much residual hexane actually shows up in food and food ingredients today. EFSA’s official position is that current safety assessments remain valid and products using hexane continue to be considered safe under existing regulations — but the agency is collecting fresh data and the re-evaluation is ongoing. The toxicology that drove the original concern is real, but it’s almost entirely occupational. n-Hexane is a recognized peripheral neurotoxin first identified in 1964, and the cases that ended up in the medical literature came from shoe factories, printing plants, and furniture workshops with poor ventilation, where workers inhaled large quantities of vaporized solvent every day for years. The neurotoxic effects are caused by a metabolite (2,5-hexanedione) that accumulates with chronic high-dose exposure. The doses involved in residual food contamination are several orders of magnitude lower. There is no clinical evidence that consumer-level exposure to hexane residues in food causes neuropathy. But it’s also true that nobody has run the long-term study at modern exposure levels in infants and small children, and that’s the gap EFSA is now asking about. The practical takeaway: if you’re buying a premium krill oil from a major brand in 2026, hexane probably isn’t in the supply chain in any meaningful way. If you’re buying the cheapest no-name omega-3 you can find on a marketplace site, you might not know.

What “solvent-free” actually means on a label

“Solvent-free” is one of those phrases that means a specific thing in a regulatory document and a fuzzier thing on a supplement bottle. There are two ways the term gets used. The first is mechanical extraction without chemical solvents at any stage. This is the Rimfrost-style approach — cook the krill, separate the oil physically using temperature, gravity, and pressure. No ethanol, no acetone, no hexane, no CO₂. The yield is lower and the equipment cost is higher, but the oil that comes out has no solvent residues to speak of because no solvent was ever introduced. This is the most defensible version of “solvent-free.” The second, more common, version is solvent extraction followed by complete solvent removal. Ethanol-extracted krill oil, once the ethanol has been distilled off and the residual measured below regulatory limits, is sometimes marketed as “ethanol-free” or “free from harmful solvents.” That’s technically accurate — the finished oil contains only trace solvent — but it’s not the same thing as having never used a solvent. The distinction matters more to clean-label purists than to anyone tracking actual health outcomes, but if the label phrase matters to you, it’s worth asking the brand to clarify which definition they’re using. A third version is the catch-all marketing phrase “no chemical processing,” which can mean anything from “we use only ethanol, which is a chemical” to “we cook and press.” When you see that phrase, the European food consumer information body EUFIC notes that you usually have to look at the manufacturer’s technical documentation to know what’s actually going on, because the label doesn’t tell you.

What residue levels actually look like

For perspective on how small “residue” gets in finished oil: EU regulations cap residual n-hexane in fats and oils at 1 mg/kg (1 ppm). For specific ingredients like degreased flours and protein products it’s higher, but for the oils most likely to end up in a supplement, the limit is parts-per-million. Modern analytical methods can detect hexane down to the parts-per-billion range, and well-run ethanol-extraction facilities typically report residual ethanol in finished krill oil well below the regulatory ceiling. Ethanol itself, for what it’s worth, is the same molecule as the alcohol in beer and wine. Residual ethanol in a finished krill oil capsule is measured in micrograms per dose — orders of magnitude below anything you’d get from a sip of a beverage. The honest concern with ethanol extraction isn’t toxicity; it’s whether the temperatures used to remove it damaged the omega-3s or the astaxanthin on the way through. That’s a process-quality question, not a solvent-residue question.

The questions actually worth asking

If you care enough about how your krill oil was made to read this far, here are the questions that separate a transparent supplier from a cagey one: What solvent, if any, is used in primary extraction? “Ethanol only” and “solvent-free mechanical” are both legitimate honest answers. “Proprietary” is a flag. The answer should be one sentence and shouldn’t require legal review. What’s the residual solvent specification, and is it tested per batch? A real supplier can tell you the spec (e.g., “ethanol < 50 ppm per batch, certificate of analysis available on request”). A reseller usually can’t. What temperatures does the oil see during processing? Krill phospholipids and astaxanthin are heat-sensitive. Low-temperature processing (under 60°C for most steps) preserves more of what makes krill oil worth taking in the first place. What’s the TOTOX value (total oxidation) of the finished oil? Industry voluntary spec is under 26; the best krill oils come in well below 10. This tells you how rancid the oil is when it gets to you — which, for any omega-3 supplement, matters more than almost anything else. A supplier that can answer those four questions in plain English is operating in good faith. A supplier that can’t is hoping you won’t ask.

A note on Captains Krill Oil

This whole article was triggered by a question we get every few weeks: “Is your krill oil extracted with hexane?” The answer is no. The honest, longer answer is that the entire premium krill oil industry has moved away from hexane over the last fifteen years, mostly because it’s a worse solvent for this particular raw material — not because of any high-minded clean-label crusade. Captains Krill Oil is mechanically extracted — cooked and pressed, no chemicals at any stage — with full COA documentation per batch. If you want the spec sheet, ask and we’ll send it. If you’d rather buy from somebody who uses a different process, that’s a choice too. The point is that you should be able to find out, in plain English, before you swallow it. That, more than any single extraction method, is what separates a supplement worth taking from one that isn’t.
Sources: EFSA technical report on hexane re-evaluation (2024) · Sun et al., Food Science & Nutrition (2019), ethanol-hexane vs. subcritical extraction comparison · Aker BioMarine Flexitech patent coverage · Rimfrost solvent-free extraction patent · EFSA P12-10 re-evaluation rationale (2025) · PubMed: n-hexane toxic neuropathy case series · Medscape: n-hexane-related peripheral neuropathy review · EUFIC: is hexane in food a cause for concern? · SGS Fresenius: hexane in food, risk assessment, analysis

Q: What is astaxanthin?

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A: Astaxanthin comes from a unique microalgae (Haematococcus pluvialis) which contains this valuable antioxidant and carotenoid. It’s an amazing substance that is believed to give salmon the stamina to swim upstream to spawn. It is also responsible for their color, and that of flamingos and krill.

A study in the Journal of Medicinal Food, found astaxanthin to be a more powerful antioxidant than any other carotenoid and even vitamin E. The krill eat this microalgae, retaining the natural astaxanthin.

Q: What are some dietary sources of Omega-3’s?

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A: There are many sources of omega-3′s from both plant and animal sources. These include: krill and krill oil, salmon and other fish, grass-fed beef, omega-3 eggs, walnuts, chia seeds, flaxseeds, pumpkin seeds, kale and squash. Krill oil has been shown to be one of the most beneficial omega-3′s considering the omega-3′s are bound to phospholipids, the same structure as human cells.