Discussions about marine omega-3 supplements usually focus on two fatty acids: EPA and DHA.
Calanus oil contains EPA and DHA, but those two fatty acids tell only part of its story.
Oil derived from the North Atlantic copepod Calanus finmarchicus naturally contains several other unusual components, including stearidonic acid (SDA), astaxanthin and a substantial fraction of long-chain fatty alcohols that Zooca® refers to as marine policosanols.
These are three very different types of compounds.
SDA is an omega-3 fatty acid. Astaxanthin is a carotenoid pigment and antioxidant. Marine policosanols are long-chain fatty alcohols that form part of the wax ester molecules characteristic of Calanus oil.
Understanding these components helps explain why Calanus oil is chemically different from conventional fish oil and krill oil.
SDA, Astaxanthin and Policosanols: The Quick Answer
| Component | What It Is | Why It Is Notable in Calanus Oil |
|---|---|---|
| SDA | Stearidonic acid, an omega-3 fatty acid | Calanus oil contains unusually meaningful amounts of SDA compared with most conventional fish and krill oils. |
| Astaxanthin | A naturally occurring red-orange carotenoid | It contributes to the characteristic deep ruby-red color of Calanus oil and provides antioxidant activity within the oil. |
| Marine Policosanols | Long-chain fatty alcohols | They form one half of the wax ester molecules that dominate Calanus oil. Major examples include eicosenol and docosenol. |
SDA is an omega-3 fatty acid.
Astaxanthin is a naturally occurring carotenoid.
Marine policosanols are long-chain fatty alcohols that are structurally built into Calanus wax esters.
Why Is Calanus Oil Different From Conventional Omega-3 Oils?
Most fish-oil products are discussed primarily in terms of their EPA and DHA content.
This makes sense because many commercial fish oils are specifically purified and concentrated to provide large quantities of those two long-chain omega-3 fatty acids.
Calanus oil follows a different model.
Rather than being a highly concentrated EPA/DHA preparation, it is a relatively intact marine lipid extracted from Calanus finmarchicus.
Published analyses show that approximately 80–90% of the oil's lipids occur as wax esters. 1, 2
The oil contains a broad mixture of fatty acids, including EPA, DHA and SDA, along with long-chain monounsaturated fatty acids and their related fatty alcohols.
It also naturally contains astaxanthin.
Consequently, EPA and DHA are only two components within a considerably broader natural lipid matrix.
What Is SDA?
SDA stands for stearidonic acid.
It is an omega-3 polyunsaturated fatty acid with the scientific designation:
This means SDA contains:
- 18 carbon atoms
- 4 carbon-carbon double bonds
- an omega-3 configuration
SDA receives considerably less attention than EPA and DHA because it is not present in high concentrations in most commonly consumed foods.
Nevertheless, it occupies an important position in omega-3 metabolism.
How Is SDA Related to EPA?
Humans can metabolically convert shorter-chain omega-3 fatty acids into longer-chain forms.
One familiar starting point is alpha-linolenic acid, or ALA.
In simplified form, part of the pathway proceeds like this:
The conversion of ALA to SDA requires an enzyme known as delta-6 desaturase.
This step is considered an important metabolic bottleneck in the pathway.
Consuming SDA bypasses this initial desaturation step because SDA has already progressed one step farther along the pathway.
For this reason, human studies have consistently found that SDA raises blood and tissue EPA more efficiently than ALA. 3, 4
SDA is a separate omega-3 fatty acid that can serve as a metabolic precursor toward EPA.
What Does Human Research Show About SDA?
One of the classic human studies comparing SDA with other omega-3 fatty acids was published in The American Journal of Clinical Nutrition in 2003.
Researchers compared supplementation with SDA, ALA and EPA in healthy adults.3
SDA supplementation increased EPA concentrations in plasma phospholipids and red blood cells.
It was substantially more effective than ALA at increasing tissue EPA, although consuming EPA directly remained more efficient.
The same study found that SDA did not significantly increase DHA.
Subsequent reviews have reached a similar conclusion: SDA is more readily converted toward EPA than ALA, but conversion from SDA all the way to DHA remains limited in humans.4, 5
How Much SDA Is Found in Calanus Oil?
One of the unusual features of Calanus oil is that SDA can represent a substantial portion of its omega-3 fatty-acid profile.
A 2020 human intervention study reported that 2 grams of the Calanus oil used in the study provided approximately:
SDA: 124 mg
EPA: 109 mg
DHA: 87 mg
In that formulation, the quantity of SDA was actually greater than either EPA or DHA individually.6
A more recent human clinical study used a Calanus oil providing approximately 168 mg of SDA per 2 grams of oil, along with 138 mg EPA and 128 mg DHA.7
These numbers also illustrate an important point:
Calanus oil is a natural marine ingredient, and its exact fatty-acid composition can vary among batches, harvests and study formulations.
Current finished-product labels and specifications should therefore be used when determining the precise amount present in a particular product.
What Is Astaxanthin?
Astaxanthin is a naturally occurring xanthophyll carotenoid.
Carotenoids are pigments produced by certain plants, algae and microorganisms and then transferred through food webs.
Astaxanthin is responsible for many of the red, pink and orange colors associated with marine life.
It contributes to the characteristic coloration of organisms including salmon, trout, shrimp, krill and other crustaceans.
It is also present naturally in Calanus finmarchicus and remains in the oil after extraction.
Chemically, astaxanthin has well-established antioxidant properties and has been the subject of extensive laboratory, animal and human research. 8
Why Is Calanus Oil Ruby Red?
One of the most visually distinctive characteristics of Calanus oil is its deep reddish color.
That color is largely associated with its naturally occurring astaxanthin.
Unlike a formulation in which astaxanthin is simply added to an oil after processing, the astaxanthin in Zooca® Calanus® Oil originates in the marine organism itself.
Zooca states that its extraction process preserves this naturally occurring astaxanthin as part of the finished marine lipid. 9
What Does Astaxanthin Do in a Marine Oil?
Polyunsaturated fatty acids contain multiple double bonds. These structures are nutritionally important, but they also make marine lipids susceptible to oxidation.
Astaxanthin can interact with reactive oxygen species and is widely recognized as an antioxidant carotenoid. 8, 10
Within the living marine organism, carotenoids such as astaxanthin form part of its natural biochemical defense system.
Zooca describes the naturally occurring astaxanthin in Calanus oil as contributing to the oxidative stability of the oil's marine lipid matrix.9
This is a different question from whether a particular dose of Calanus oil produces a specific antioxidant health effect in a person.
Astaxanthin has been studied independently in human clinical research, but results obtained using concentrated astaxanthin supplements should not automatically be assumed to occur from the smaller amount naturally present in any particular serving of Calanus oil.
The most straightforward conclusion is therefore that astaxanthin is a naturally occurring component of Calanus oil with established antioxidant chemistry and an important role in the oil's composition.
How Much Astaxanthin Is in Calanus Oil?
The amount can vary.
For example, the Calanus oil used in a 2020 human intervention study contained approximately:
1.8 mg astaxanthin per gram of Calanus oil
A more recent clinical formulation reported approximately 1.0 mg per gram. 6, 7
Zooca's current ingredient information describes Zooca® Calanus® Oil as containing approximately:
1.4 mg of naturally occurring astaxanthin per gram of oil
Again, these figures should not be treated as universal constants. Current product specifications or a certificate of analysis are the appropriate source for the amount in a particular batch.
What Are Policosanols?
The term policosanol generally refers to a mixture of long-chain aliphatic fatty alcohols.
Plant-derived policosanol preparations have historically been obtained from materials such as:
- sugarcane wax
- rice bran
- wheat germ
- beeswax
- other natural waxes
Calanus oil contains a different marine fatty-alcohol profile.
Zooca uses the term marine policosanols for the long-chain fatty alcohol component naturally present within its Calanus wax esters.
These compounds are not added afterward as a separate supplement.
They are structurally built into the wax ester molecules produced by Calanus finmarchicus.
Are Marine Policosanols the Same as Plant Policosanols?
They belong to the same general chemical family of long-chain fatty alcohols, but their compositions are not identical.
This is an important scientific distinction.
Traditional plant policosanol preparations often contain longer, predominantly saturated fatty alcohols such as:
- octacosanol (C28)
- triacontanol (C30)
- hexacosanol (C26)
The major fatty alcohols in Calanus oil are instead primarily C20 and C22 monounsaturated fatty alcohols.
The two particularly prominent examples are:
- Eicosenol — 20:1
- Docosenol — 22:1
A 2020 scientific review specifically cautioned that health effects reported for traditional plant-derived policosanol preparations cannot simply be extrapolated to the shorter-chain, monounsaturated fatty alcohols found in Calanus oil.2
“Marine policosanol” is a useful description for the substantial long-chain fatty alcohol fraction of Calanus oil, but it should not imply that Calanus fatty alcohols are chemically identical to every traditional plant policosanol preparation.
Why Does Calanus Oil Contain So Many Fatty Alcohols?
The answer lies in the unusual molecular structure of the oil.
A wax ester contains two major components:
This differs from a triglyceride, where three fatty acids are attached to glycerol.
Because approximately 80–90% of Calanus oil consists of wax esters, a substantial long-chain fatty-alcohol fraction is an unavoidable consequence of that molecular structure.
In other words, the fatty alcohols are not a minor contaminant.
They represent one of the basic structural building blocks of the dominant lipid class in Calanus oil.
What Are Eicosenol and Docosenol?
Eicosenol and docosenol are the two principal long-chain monounsaturated fatty alcohols described in Calanus oil.
| Fatty Alcohol | Carbon Length | Related Fatty Acid |
|---|---|---|
| Eicosenol | C20:1 | Related to the C20:1 fatty-acid family |
| Docosenol | C22:1 | Related to the C22:1 fatty-acid family |
Scientific analyses of Calanus oil identify eicosenol and docosenol as dominant components of its fatty-alcohol fraction. 1, 2
Their corresponding long-chain monounsaturated fatty acids include compounds such as gondoic and cetoleic acid.
Both the fatty alcohols and the corresponding fatty acids have attracted research interest because they are relatively uncommon in conventional discussions of omega-3 supplements.
What Happens to Fatty Alcohols After Digestion?
During digestion, wax esters can be hydrolyzed, breaking the bond between the fatty acid and fatty alcohol.
Research on dietary waxes indicates that released long-chain fatty alcohols can be absorbed and metabolized. 11
Classical biochemical research also demonstrates that fatty alcohols can be oxidized into their corresponding fatty acids.
A major review of dietary wax metabolism described a metabolic pathway involving conversion among fatty alcohols, fatty aldehydes and fatty acids.11
Researchers studying Calanus oil have therefore proposed that some of its long-chain fatty alcohols may eventually contribute to the pool of related long-chain monounsaturated fatty acids after absorption.
However, the quantitative importance of this process and its specific physiological effects in humans remain under investigation. 2
How Much of Calanus Oil Is Marine Policosanol?
The long-chain fatty-alcohol fraction is substantial.
Published human studies using Calanus oil have reported fatty-alcohol concentrations ranging from approximately 29% to 39% of the oil, depending upon the formulation studied. 6, 7, 12
Zooca's current ingredient information describes approximately 40% of Zooca® Calanus® Oil as marine policosanols—the long-chain alcohol component of the wax ester structure. 13
A triglyceride uses glycerol as its backbone.
A Calanus wax ester uses a long-chain fatty alcohol.
Therefore, a wax ester-rich oil naturally contains a substantial amount of these fatty alcohols.
How SDA, Astaxanthin and Policosanols Fit Together
SDA, astaxanthin and marine policosanols should not be viewed as three versions of the same nutrient.
They occupy entirely different roles within the chemistry of Calanus oil.
| Component | Chemical Category | Role in Calanus Oil |
|---|---|---|
| SDA | Omega-3 fatty acid | Part of the oil's broad fatty-acid spectrum and a metabolic precursor toward EPA. |
| Astaxanthin | Carotenoid | Naturally occurring pigment with antioxidant activity that contributes to the oil's ruby-red color and oxidative stability. |
| Marine Policosanols | Long-chain fatty alcohols | Structural components of the wax ester molecules that dominate Calanus oil. |
They coexist within the natural lipid system produced by Calanus finmarchicus.
This is why describing Calanus oil solely by the number of milligrams of EPA and DHA provides only a partial picture of its composition.
How Does This Compare With Fish Oil and Krill Oil?
Fish oil, krill oil and Calanus oil can all supply EPA and DHA, but their broader compositions differ.
| Characteristic | Fish Oil | Krill Oil | Calanus Oil |
|---|---|---|---|
| EPA | Yes | Yes | Yes |
| DHA | Yes | Yes | Yes |
| Significant SDA | Usually not a defining feature | Usually not a defining feature | Yes |
| Naturally Occurring Astaxanthin | Usually little or none unless added | Yes | Yes |
| Primary Lipid Structure | Generally triglycerides or processed derivatives | Substantial phospholipid fraction | Predominantly wax esters |
| Large Fatty-Alcohol Fraction | No | No | Yes |
This does not mean that one oil is automatically superior to every other oil.
It means that the oils are chemically different and should not be evaluated solely by treating EPA and DHA as their only meaningful components.
What Has Science Established—and What Is Still Being Studied?
Calanus oil research has expanded considerably, but it is useful to separate established facts from developing hypotheses.
Well Established
- Calanus oil contains significant amounts of the omega-3 fatty acid SDA.
- Human studies outside Calanus research demonstrate that SDA can increase tissue EPA more efficiently than ALA.
- Calanus oil naturally contains astaxanthin.
- Astaxanthin is a carotenoid with established antioxidant properties.
- Calanus oil contains a substantial long-chain fatty-alcohol fraction because those alcohols are integral components of its wax esters.
- Eicosenol and docosenol are prominent fatty alcohols in Calanus oil.
- Dietary wax esters can be hydrolyzed and their fatty-acid and fatty-alcohol components can be absorbed and metabolized.
Still Being Investigated
- The extent to which SDA contributes independently to the effects observed in Calanus-oil intervention studies.
- Whether the amount of naturally occurring astaxanthin in a particular serving of Calanus oil produces specific clinical effects beyond its role within the oil.
- The precise human metabolic effects of the C20–C22 marine fatty alcohols found in Calanus oil.
- How much conversion of those fatty alcohols to corresponding fatty acids contributes to the overall physiological response.
- Whether the various components of Calanus oil act differently together than they would when consumed individually.
What Does This Mean for Arctic Ruby Oil?
Arctic Ruby Oil uses Zooca® Calanus® Oil derived from Calanus finmarchicus.
Its marine oil therefore naturally contains much more than the familiar omega-3 fatty acids EPA and DHA.
The broader natural lipid system includes:
- SDA
- EPA
- DHA
- long-chain monounsaturated fatty acids
- marine policosanols / long-chain fatty alcohols
- naturally occurring astaxanthin
- numerous additional marine fatty acids
Most importantly, these are not simply a list of unrelated ingredients blended together afterward.
They originate within the natural lipid system of Calanus finmarchicus.
Wax esters provide the structure.
SDA, EPA, DHA and other fatty acids form part of the fatty-acid spectrum.
Marine policosanols form the long-chain fatty-alcohol side of the wax esters.
Astaxanthin is a naturally occurring carotenoid retained within the marine oil.
That combination is one of the principal reasons Calanus oil is chemically distinct from conventional fish oil and krill oil.
Frequently Asked Questions
What is SDA in Calanus oil?
SDA stands for stearidonic acid. It is an omega-3 fatty acid designated 18:4 n-3. SDA occurs naturally in Calanus oil and can be metabolically converted toward EPA in the human body.
Is SDA the same as EPA?
No. SDA and EPA are different omega-3 fatty acids. SDA is an 18-carbon omega-3, while EPA is a 20-carbon omega-3. SDA lies earlier in the metabolic pathway and can be converted toward EPA.
Can SDA turn into DHA?
Human research indicates that SDA increases EPA more efficiently than ALA, but conversion through the pathway to DHA is limited. SDA therefore should not be considered equivalent to consuming DHA directly.
Does Calanus oil naturally contain astaxanthin?
Yes. Astaxanthin occurs naturally in Calanus finmarchicus and is retained in Calanus oil. It contributes to the oil's characteristic deep red or ruby-red appearance.
Is astaxanthin added to Calanus oil?
In Zooca® Calanus® Oil, the astaxanthin originates naturally from the Calanus raw material rather than being added simply to create the oil's color.
What are marine policosanols?
Marine policosanols is the term Zooca uses for the long-chain fatty alcohol fraction naturally present in its Calanus wax esters. The predominant fatty alcohols include eicosenol and docosenol.
Are marine policosanols the same as sugarcane policosanols?
Not exactly. Both are mixtures of long-chain fatty alcohols, but their molecular profiles differ. Traditional plant policosanol preparations commonly contain longer saturated fatty alcohols such as octacosanol, while Calanus oil is dominated by shorter C20 and C22 monounsaturated fatty alcohols.
Why are there so many fatty alcohols in Calanus oil?
Because Calanus oil is dominated by wax esters. Each wax ester consists of one fatty acid joined to one long-chain fatty alcohol. A wax ester-rich oil therefore naturally contains a substantial fatty-alcohol fraction.
Are fatty alcohols the same as drinking alcohol?
No. Long-chain fatty alcohols such as eicosenol and docosenol are lipid molecules and are chemically very different from ethanol, the alcohol present in alcoholic beverages.
How much marine policosanol is in Calanus oil?
The amount varies with the oil and analytical method. Published study formulations have reported fatty-alcohol fractions of roughly 29–39% of the oil. Zooca's current ingredient information describes its Calanus oil as containing approximately 40% marine policosanols.
How much astaxanthin is in Zooca Calanus Oil?
Zooca currently describes its Calanus oil as containing approximately 1.4 mg of naturally occurring astaxanthin per gram of oil. Natural concentrations can vary, so current product specifications should be consulted for exact amounts.
Does Arctic Ruby Oil contain SDA, astaxanthin and marine policosanols?
Arctic Ruby Oil uses Zooca® Calanus® Oil, whose characteristic natural composition includes SDA, EPA, DHA, long-chain fatty alcohols described as marine policosanols, and naturally occurring astaxanthin.
The Bottom Line
Calanus oil is more than a source of EPA and DHA.
It is a naturally complex marine lipid derived from Calanus finmarchicus.
Three of its particularly interesting components are SDA, astaxanthin and long-chain fatty alcohols known commercially as marine policosanols.
SDA is an omega-3 fatty acid. It occurs earlier than EPA in the omega-3 metabolic pathway and is converted toward EPA more efficiently than ALA.
Astaxanthin is a naturally occurring carotenoid. It contributes to Calanus oil's deep ruby-red color and provides antioxidant activity within the marine lipid.
Marine policosanols are long-chain fatty alcohols. They are not simply added ingredients—they form one half of the wax ester molecules that dominate Calanus oil.
These compounds coexist alongside EPA, DHA and numerous other fatty acids within the natural lipid system of Calanus finmarchicus.
That broad composition helps explain why evaluating Calanus oil only by counting its milligrams of EPA and DHA does not provide a complete description of what the oil contains.
It is the combination of wax ester structure, a broad fatty-acid spectrum, long-chain fatty alcohols and naturally occurring astaxanthin that makes Calanus oil a distinct category of marine lipid.
Scientific References
- Pedersen AM, Vang B, Olsen RL. “Oil from Calanus finmarchicus—Composition and Possible Use: A Review.” Journal of Aquatic Food Product Technology. 2014;23(6):633–646. DOI: 10.1080/10498850.2012.741662
- Schots PC, Pedersen AM, Eilertsen KE, Olsen RL, Larsen TS. “Possible Health Effects of a Wax Ester Rich Marine Oil.” Frontiers in Pharmacology. 2020;11:961. DOI: 10.3389/fphar.2020.00961
- James MJ, Ursin VM, Cleland LG. “Metabolism of Stearidonic Acid in Human Subjects: Comparison With the Metabolism of Other n-3 Fatty Acids.” American Journal of Clinical Nutrition. 2003;77(5):1140–1145. DOI: 10.1093/ajcn/77.5.1140
-
Whelan J.
“Dietary Stearidonic Acid Is a Long Chain (n-3)
Polyunsaturated Fatty Acid With Potential Health Benefits.”
Journal of Nutrition. 2009.
View on PubMed - Baker EJ, Miles EA, Burdge GC, Yaqoob P, Calder PC. “Metabolism and Functional Effects of Plant-Derived Omega-3 Fatty Acids in Humans.” Progress in Lipid Research. 2016;64:30–56. DOI: 10.1016/j.plipres.2016.07.002
- Wasserfurth P, Nebl J, Schuchardt JP, Müller M, Boßlau TK, Krüger K, Hahn A. “Effects of Exercise Combined with a Healthy Diet or Calanus finmarchicus Oil Supplementation on Body Composition and Metabolic Markers—A Pilot Study.” Nutrients. 2020;12(7):2139. DOI: 10.3390/nu12072139
-
“Calanus Oil and Lifestyle Interventions Improve Glucose
Homeostasis in Obese Subjects with Insulin Resistance.”
Marine Drugs. 2025.
Includes detailed compositional analysis of the Calanus oil
formulations used in the human intervention.
View Full Study - Ambati RR, Phang SM, Ravi S, Aswathanarayana RG. “Astaxanthin: Sources, Extraction, Stability, Biological Activities and Its Commercial Applications—A Review.” Marine Drugs. 2014;12(1):128–152. DOI: 10.3390/md12010128
-
Zooca® / Calanus AS.
“Astaxanthin and Natural Protection.”
Current technical information concerning naturally occurring
astaxanthin in Zooca® Calanus® Oil.
View Zooca Astaxanthin Information - Brotosudarmo THP, Limantara L, Setiyono E, Heriyanto. “Structures of Astaxanthin and Their Consequences for Therapeutic Application.” International Journal of Food Science. 2020;2020:2156582. DOI: 10.1155/2020/2156582
- Hargrove JL, Greenspan P, Hartle DK. “Nutritional Significance and Metabolism of Very Long Chain Fatty Alcohols and Acids From Dietary Waxes.” Experimental Biology and Medicine. 2004;229(3):215–226. DOI: 10.1177/153537020422900301
- Research examining Calanus oil supplementation and exercise has reported Calanus oil formulations containing approximately 39% fatty alcohols, further demonstrating the substantial fatty-alcohol fraction associated with the oil's wax ester structure. See published Calanus oil human exercise-intervention literature.
-
Zooca® / Calanus AS.
“Marine Policosanols – The Unique Bioactive.”
Current technical information describing the long-chain fatty
alcohol fraction of Zooca® Calanus® Oil.
View Zooca Marine Policosanol Information
Additional Source Information
Zooca® / Calanus AS of Norway supplies the Calanus oil used in Arctic Ruby Oil and publishes current technical information concerning the wax ester structure, fatty-acid spectrum, marine policosanols and naturally occurring astaxanthin in Zooca® Calanus® Oil.
Because Calanus oil is derived from a biological marine resource, exact concentrations can vary. Current ingredient specifications, finished-product labels and certificates of analysis should be used whenever an exact concentration for a particular batch is required.