Shark Oil (Shark Liver Oil): A Comprehensive Reference
1. Identity, Source, and Nomenclature
Shark liver oil (SLO) is a lipid-rich extract obtained from the livers of sharks, primarily deep-sea species.
SLO is obtained from the livers of sharks, primarily Centrophorus squamosus, Cetorhinus maximus, and Squalus acanthias — commonly known as deep-sea shark, basking shark, and dogfish shark, respectively.
SLO is purified from sharks like Centrophorus squamosus, Cetorhinus maximus, Squalus acanthias, basking and dogfish sharks that live in cold, deep oceans.
Other species utilized include the Greenland shark (Somniosus microcephalus) and the bramble shark (Echinorhinus brucus). The genus name Squalus directly gave rise to the name of the oil's principal compound: squalene received its name as a result of its first isolation from the liver oil of sharks (Squalus spp.).
Chemically, squalene is designated as 2,6,10,15,19,23-hexamethyl-2,6,10,14,18,22-tetracosahexaene (molecular formula C₃₀H₅₀). Squalene, the second largest constituent of SLO, is a polyunsaturated triterpene containing six isoprene units and thus has a structural similarity with various naturally occurring polyprenyl compounds, including vitamin E. Later, squalene was found in a variety of vegetable oils, including olive, palm, wheat-germ, and rice bran oils. Chemically, squalene is a polyprenyl compound, having a structural similarity with β-carotene, coenzyme Q10, and vitamins A, E, and K.
The other principal class of bioactive compounds, the alkylglycerols (AKGs), are formally named 1-O-alkylglycerol ether lipids. Structurally, they are alkyl ethers of glycerol. The three most commonly cited individual alkylglycerols found in SLO are batyl alcohol (1-O-octadecylglycerol), chimyl alcohol (1-O-hexadecylglycerol), and selachyl alcohol (an unsaturated variant). After separation by chromatography on silicic acid, monounsaturated glycerol ethers have been separated from the saturated homologues, in particular from 1-O-octadecylglycerol (batyl alcohol) and 1-O-hexadecylglycerol (chimyl alcohol), via urea complexation.
The oil itself has distinctive sensory characteristics. The oil has a dark yellow to brown shade and a pungent aroma and taste. Commercially, SLO may be found in liquid or capsule form, or as an ingredient in skin creams and lip balms. It is a component of some moisturizing skin lotions and hemorrhoid medications.
2. Chemical Composition
The precise composition of SLO varies markedly across shark species. Characterization of the deep-sea shark Centrophorus squamosus revealed that the oil is composed of 60% unsaponifiable matter, containing 45% squalene, 4.5% cholesterol, and 10% of linear saturated and monounsaturated glycerol ethers with 14–18 carbon atoms. By contrast, the preparation used in a Japanese clinical vascular safety study was almost free of n-3 long-chain fatty acids and mainly composed (w/w) of squalene (38.8%) and alkylglycerols (43.6%), indicating that a daily dose of the SLO capsule contained squalene at 582 mg in weight.
Biochemical analysis of the bramble shark (Echinorhinus brucus) liver oil found a different fatty acid profile, including the presence of palmitic acid (15%), oleic acid (12%), stearic acid (8%), docosahexaenoic acid — DHA (18%), and eicosapentaenoic acid — EPA (16%). The oil was also found to be a good source of squalene (38.5%) and fat-soluble vitamins A, D, and K (vitamin A: 17.08 mg/100 g of oil, vitamin D: 15.04 mg/100 g of oil, and vitamin K: 11.45 mg/100 g of oil).
Several distinct alkylglycerol variants have also been identified in Greenland shark liver oil. Compounds such as 1-O-(2-methoxyhexadecyl)-glycerol, 1-O-(2-methoxy-4-hexadecenyl)-glycerol, and 1-O-(2-methoxy-4-octadecenyl)-glycerol have been isolated from Greenland SLO. SLO is considered to be the richest natural source of squalene.
A key distinction from conventional fish oil is the relative lack of omega-3 fatty acids. Shark liver oils are rich in alkylglycerols and squalene but contain relatively low amounts of n-3 polyunsaturated fatty acids. The alkylglycerol composition also varies by chain length and saturation. The composition of natural alkyl-Gro mix contains several alkyl-Gro varying by chain length and unsaturation. Six prominent constituents of the natural mix include 12:0, 14:0, 16:0, 18:0, 16:1 n-7, and 18:1 n-9 alkyl-Gro.
3. Traditional and Historical Use
Shark liver oil is an oil obtained from the livers of sharks. It has been used for centuries as a folk remedy to promote the healing of wounds and as a remedy for respiratory tract and digestive system problems.
The most thoroughly documented traditional use comes from Scandinavia. SLO is an ancient remedy among the fishermen on the west coast of Norway and Sweden. Shark liver oil has been used as a folk medicine by the inhabitants of fishing villages along the west coast of Norway and Sweden for hundreds of years. The fishermen cooked the livers to extract the oil, then stored it in cleaned and preserved shark stomachs. The oil was used to promote wound healing and as a general remedy for conditions related to the respiratory tract and the digestive system. It was also used to treat "glandular diseases," which we commonly refer to as swollen lymph nodes.
SLO has been traditionally used by Scandinavian fishermen for the treatment of a variety of ailments, including wounds, heart disease, and infertility. Traditional use also extended to dermatological conditions: SLO was initially employed by Scandinavian fishermen to treat skin conditions, respiratory ailments, and certain cancers.
In Japan, SLO was known by a different name entirely. Japanese seamen called it samedawa, or "cure all." SLO has long been used as a dietary supplement with health-promoting activities, particularly for cardiovascular health, in Japan.
The historical basis for SLO's use in cancer-related traditions was rooted in popular observation rather than science. In Scandinavian traditional medicine, shark liver oil was an essential part of cancer therapy. This traditional medical approach was based on early "folk" observations that sharks rarely suffer from tumors and successfully resist numerous infections. This observation was simplistic and incorrect, as the incidence of cancer in sharks is multifactorial and requires careful evaluation — sharks can indeed develop cancer.
The scientific transition from folk remedy to research subject began in the 1950s. The discovery of alkylglycerols dates back to the 1950s, when Swedish physician Astrid Brohult found that administering calf bone marrow helped in the recovery of white blood cells in children undergoing radiotherapy for leukemia. The isolated active ingredient was identified as alkylglycerols. In 1963, Astrid Brohult published a thesis on alkylglycerols and their use in radiation treatment. The alkylethers used were isolated from Greenland shark liver (Somniosus microcephalus) by molecular distillation followed by hydrolysis.
The biochemical discovery of alkylglycerols predated this clinical work. In 1922, Tsujimoto and Toyama found AKG in SLO, and Sir Robert Robinson, a Nobel laureate, first synthesized them in 1930. Squalene itself was isolated somewhat earlier: in 1916, Tsujimoto Mitsumaru, a Japanese chemist, successfully isolated squalene (C₃₀H₅₀) from shark liver oil (Squalus spp.) and found that the compound was a highly unsaturated isoprenoid hydrocarbon containing six double bonds.
4. Key Constituents and Mechanisms of Action
4.1 Alkylglycerols (AKGs)
Shark liver oil has been used for over 40 years as both a therapeutic and preventive agent. The active ingredients in shark liver oil have been found to be a group of ether-linked glycerols known as alkylglycerols.
Alkylglycerols are not unique to shark liver oil — they are endogenous lipids in mammals. Alkylglycerols are lipids naturally present in humans in immune organs such as bone marrow, liver, and spleen, as well as in breast milk. Colostrum from human milk contains a higher concentration of unsubstituted glycerol ethers compared to mature milk; human milk contains ten times higher concentrations than cow's milk and two times higher than sheep's milk. The highest concentration of alkylglycerols in neutral lipids is found in human bone marrow and in cervical cancer cells.
The primary proposed mechanism for AKG immunostimulation involves modulation of immune cell signaling. The level of natural alkylglycerols rises within tumor cells, apparently in an effort to control cell growth. Recent studies indicate that the activation of protein kinase C, an essential step in cell proliferation, can be inhibited by alkylglycerols. This action suggests a competitive inhibition of 1,2-diacylglycerol by alkylglycerols.
AKGs also modulate platelet-activating factor (PAF) and diacylglycerol (DAG) metabolism. Alkylglycerols may control immune response possibly through modification of platelet activating factor (PAF) and diacylglycerol (DAG) production.
At the cellular level, AKGs exert effects on macrophage function. Further studies on the immunostimulatory action of alkylglycerols suggest a primary action on the macrophage. The process of macrophage activation has been demonstrated with both synthetic and natural alkylglycerols. While the exact mechanism has not been found, both an autocrine and paracrine system have been suggested. Literature reports show that alkylglycerols enhance Fc-receptor mediated phagocytosis, increase humoral immune response, and delay hypersensitivity reactions.
AKGs also contribute to the structural biology of immune cells. Alkylglycerols are precursors of phospholipids that contribute to the structure and function of membranes in certain immune cells such as white blood cells and macrophages.
Experimental research has identified a potentially significant neurological application. Several experimental studies have shown the ability of alkylglycerols to open the blood-brain barrier to facilitate the access of therapeutic drugs to the central nervous system.
The anti-tumor activity of specific AKG molecular species has been studied in animal models. 16:1 and 18:1 alkyl-Gro showed strong activity in reducing lung metastasis number, while saturated alkyl-Gro had weaker (16:0) or no (12:0, 14:0, 18:0) effect — indicating that anti-tumor potency is structure-dependent. Alkylglycerols and squalene have antitumour activity, that is possibly based on different mechanisms, i.e., induction of apoptosis of neoplastic cells, suppression of signal transduction, inhibition of angiogenesis, and promoting of transmembrane transport of cytotoxic agents.
4.2 Squalene
In vitro experimental evidence indicates that squalene is a unique antioxidant molecule exhibiting highly effective oxygen-scavenging activity. The presence of the double bond structure enabled the isoprenoid hydrocarbon to act as a strong antioxidant and natural antibiotic.
Squalene occupies a central metabolic role in humans. Squalene is an intermediate in the synthesis of cholesterol and bypasses HMG-CoA reductase in this pathway. Therefore, it has been studied for its effects on atherosclerosis and cardiovascular disease. Relevant to skin biology, squalene appears to play an antioxidant role by decreasing damage caused by oxidation from free radicals to the skin. As a main component of sebum, squalene's role is to protect skin surfaces from lipid peroxidation due to ultraviolet light exposure. Additionally, squalene is deeply absorbed into the skin, increasing skin flexibility and does not leave an oily residue, which has increased its attractiveness for cosmetic purposes.
At the pharmaceutical level, squalene's immunostimulatory properties have been exploited as a vaccine adjuvant. Squalene-based oil-in-water formulations are used as vaccine adjuvants that boost immune responses to antigens. Squalene is a natural linear triterpene found in high amounts in certain fish liver oils, especially from deep-sea sharks, and to a lesser extent in a wide variety of vegetable oils. Squalene-based vaccine adjuvants, such as MF59 (Novartis), AS03 (GlaxoSmithKline Biologicals), or AF03 (Sanofi) are included in seasonal vaccines against influenza viruses. Squalene enhances antigen presentation and induction of inflammatory response.
4.3 Omega-3 Polyunsaturated Fatty Acids (PUFAs)
PUFAs, mostly omega-3 fatty acids that are also components of SLO, may influence the body's immune function due to their anti-inflammatory effects. The atheroprotective effect of omega-3 intake has been associated with a reduction of VLDL synthesis and of small LDL particles. The omega-3 content of SLO is, however, variable by species and is generally lower than in conventional fish oil preparations.
5. Scientific Evidence by Area of Use
5.1 Oncology Support and Radioprotection
This is the area with the longest and most substantive human clinical history for SLO. Initial clinical use was for treating leukemias, and later to prevent radiation sickness from cancer x-ray therapy.
The foundational human research was conducted by Swedish physician Astrid Brohult and her husband over several decades. In patients with uterine cancer, a decrease in white cells and thrombocytes, which usually occurs during radiation treatment, is less pronounced if AKG are administered during this treatment. In a prospective, controlled study of 250 patients with cervical cancer, Astrid Brohult administered alkylglycerol esters to every second patient prior to radiation treatment.
In 1970, Brohult and her husband Sven Brohult, PhD, first reported the positive effects of shark-derived alkylglycerols on cancer patients, and in 1986 found higher survival rates in cervical cancer patients who took alkylglycerols while receiving radiation treatment.
Specific outcomes in the radiation studies include mitigation of fistula formation: patients supplementing with shark liver oil experienced significantly less bone marrow suppression during radiation treatment than those who did not. In one controlled study, cervical cancer patients given alkylglycerols prior to radiation therapy showed a 47% reduction in fistulas — a serious radiation injury — compared to controls.
In patients with uterine cancer, it was shown that the decrease in white cells and thrombocytes which usually occurs during radiation treatment is less pronounced if alkylglycerols are administered during this treatment. In experiments on irradiated rats, it was shown that alkylglycerols or their esters inhibit, to a certain extent, the decrease of both megakaryocytes and nucleated cells in the bone marrow in connection with irradiation.
Evidence assessment: The Brohult studies are the primary human clinical evidence base. They represent controlled but non-randomized prospective trials from one research group, conducted primarily in the 1960s–1980s. Claims about the anticancer and immunostimulant properties of shark liver oil supplements are mainly based on in vitro or animal studies. Some authors nevertheless conclude that the alkylglycerols from shark liver oil may be useful as an adjunct to conventional cancer treatments and as a prophylactic. Shark liver oil is promoted as a dietary supplement, and additional claims have been made that it can treat maladies such as cancer, HIV, radiation sickness, and the common cold. To date, none of these claims has been medically validated, and shark liver oil alone is not a medication prescribed or utilized by American physicians.
5.2 Immune Modulation
Shark liver oil is a source of alkylglycerols which have been studied as anti-cancer agents in several clinical trials. Moreover, alkylglycerols have been investigated for their ability to boost the immune system.
A small open-label study in elderly surgical patients provides one of the more specific human datasets on immunological outcomes. An open spontaneous study was performed on 40 very old surgical patients preoperatively treated with alkylglycerols (500 mg twice a day for 4 weeks), in order to reduce the risks of operation, counteracting postoperative inflammatory and anergic conditions, thus achieving quick and plain recovery.
A systematic scoping review of SLO and immunological outcomes identified a modest but consistent signal. A total of 16 articles met inclusion criteria, including human studies and in vivo animal models with various baseline health conditions. SLO has a broad yet selective immunomodulatory effect that shows an adaptive response depending on context, such as inflammatory conditions, cancer, or infection. The inconsistencies in results highlighted the biological complexity and the context-dependent role of SLO in the immune system. Despite this, alkylglycerols (AKG) emerge as a key bioactive component, with some studies suggesting potential dose-dependent effects and exploring the structure-activity relationship of different AKG forms in modulating the immune response.
Animal data also support an immunostimulatory role for squalene. Effects of squalene on cellular and non-specific immune responses and antitumor activity in mice were investigated. Cellular and non-specific immunological assay parameters adopted in the study were delayed-type hypersensitivity reaction and rosette-forming cells for cellular immunity, and activities of natural killer cells and phagocytes for non-specific immunity. Squalene resulted in marked increases of cellular and non-specific immune functions and enhancement of host resistance to tumor challenge in a dose-dependent manner.
Evidence assessment: Evidence for immune modulation in humans remains preliminary. Most supporting mechanistic data comes from in vitro and animal experiments, and the human studies that do exist are small, often uncontrolled, and conducted in specific clinical subpopulations.
5.3 Cardiovascular Effects
Squalene's role in cholesterol biochemistry has driven interest in SLO for cardiovascular health. As an intermediate in the biosynthesis of phytosterol and cholesterol, evidence of squalene having beneficial effects against cardiovascular disease revealed that the mechanism was similar to that of statins, which was associated with the inhibitory activity on HMG-CoA reductase in the liver, and downregulates the conversion from acetyl CoA to cholesterol.
Animal studies from the Farvin group showed that supplementation of squalene extracted from shark liver oil to isoprenaline-MI induced rats for 45 days demonstrated a significant decrease in total cholesterol and triglycerides in comparison to the control group. Meanwhile, the HDL-C in the MI-supplemented squalene group showed significant increments when compared to the MI-control group. Prior treatment with squalene in isoprenaline-MI induced rats also significantly increased the antioxidant enzymes (GST and GPx) and antiperoxidative enzyme (CAT and SOD) levels.
Evidence in humans is contradictory. On one hand, some studies attribute squalene with anti-atherosclerotic effects. On the other, animal studies using dietary squalene supplementation showed paradoxical elevations in cholesterol. Squalene effects on cholesterol were assessed in hamsters given diets with 0.05%, 0.1%, or 0.5% squalene or 0.05% squalene-containing SLO for 4 weeks. Total cholesterol concentrations increased by 32% in the 0.05% squalene group, 23% in the 0.1% squalene group, 35% in the 0.5% squalene group, and 19% in the SLO group when compared with the control group. Statistical significance (P < 0.05) was reached in the 0.05% and 0.5% squalene groups only. A similar effect on triglycerides was also noted. High-density lipoprotein levels increased in the 0.1% squalene, 0.5% squalene, and 0.05% SLO groups compared with the control group.
Research has also shown that the direction of squalene's effect on cholesterol may depend on whether it is administered orally. Results of previous studies have reported that exogenous squalene rather inhibits HMG-CoA reductase, a key enzyme for cholesterol synthesis, and orally administered SLO, or a dietary source of squalene, did not increase serum level of cholesterol.
Evidence assessment: Evidence on SLO's cardiovascular effects in humans is conflicting. The preponderance of cardiovascular data comes from animal models. Contradictory cholesterol results across species and study designs preclude firm conclusions for human application.
5.4 Inflammation and Erythrocyte Membrane Composition
A 2021 human pilot study published in Nutrients examined the short-term biochemical effects of SLO supplementation. Shark liver oil supplementation has been widely used recently in the prevention and treatment of human diseases. The researchers analyzed the impact of short-term SLO supplementation on certain biochemical parameters and erythrocyte fatty acid composition in a group of young healthy women. Their results showed that 6 weeks of SLO supplementation led to a significant decrease in C-reactive protein levels in sera and intracellular cholesterol levels in peripheral blood mononuclear cells.
The study also found changes in membrane lipid composition: SLO supplementation caused a significant increase in the content of the polyunsaturated omega-3 fatty acids: docosahexaenoic acid, docosapentaenoic acid, and α-linolenic acid. In the group of omega-6 fatty acids, a significant elevation of arachidonic and dihomo-gamma-linoleic acid content was observed. The omega-3 index increased significantly from 3.6% (before) to 4.2% (after supplementation).
Evidence assessment: These findings are promising but limited by the study's small sample size, the exclusive enrollment of young healthy women, the lack of a placebo arm, and the short supplementation period.
5.5 Dermatological and Topical Applications
SLO has been classified as a topical protectant. Squalene appears to play an antioxidant role by decreasing damage caused by oxidation from free radicals to the skin. Squalene is a biocompatible oil with anti-oxidant, anti-inflammatory, and immunomodulatory properties. Squalane, its fully saturated version, has moisturizing, antioxidant, and UV-protective properties. In cosmetics, fully saturated squalane (C₃₀H₆₂), generated through squalene hydrogenation, is a valued ingredient due to its emollient, moisturizing, and antioxidant properties. Squalane easily penetrates human skin, hence serving as a liquid vehicle that facilitates the absorption of other bioactive molecules.
A topical SLO product marketed under the name isolutrol has been studied for acne. SLO marketed under the name isolutrol has been studied in a clinical trial of acne at a topical concentration of 0.15 g per 100 mL.
Evidence assessment: The skin-moisturizing and barrier-protective effects of squalane (the saturated, stable derivative of squalene) are well-established in cosmetic science. Evidence for the clinical treatment of dermatological diseases using oral SLO remains sparse.
5.6 Hematopoiesis and Blood Cell Support
Oral SLO or alkylglycerol mix from shark liver sources has several in vivo biological activities including stimulation of hematopoiesis and immunological defenses, or anti-tumor and anti-metastasis activities in vivo. The hematopoiesis-stimulating effect underpins the radioprotective observations — by supporting bone marrow function, AKGs may reduce the severity of radiation-induced leukopenia and thrombocytopenia.
5.7 Squalene as Pharmaceutical Adjuvant
Beyond dietary supplementation, squalene extracted from SLO has been used as the active lipid component in approved vaccine adjuvant systems. Squalene is currently used for numerous vaccine and drug delivery emulsions due to its stability-enhancing properties and biocompatibility. Squalene-based vaccine adjuvants, such as MF59 (Novartis), AS03 (GlaxoSmithKline Biologicals), or AF03 (Sanofi), are included in seasonal vaccines against influenza viruses. All three are approved for use in both seasonal and pandemic influenza vaccines. Studies in mice and non-human primates showed that, besides their role as antigen carriers, squalene-based adjuvants enhance both innate and adaptive immune responses.
MF59 enhances immune responses to antigen by targeting three different cell types, including monocytes, macrophages, and granulocytes. MF59 has a range of effects on these cells, including increased antigen uptake, release of chemoattractants, and induction of cell differentiation.
Regarding the safety of squalene in vaccine adjuvants and its relationship to the proposed Gulf War syndrome, the Persian Gulf War syndrome was believed to be linked to antibodies developed to squalene contained in vaccinations. However, clinical data have suggested that antibodies against squalene have been detected in healthy individuals, and the presence of these antibodies is not increased by vaccines containing squalene. Antisqualene antibodies are not increased by immunization with vaccines containing the MF59 adjuvant. These data extend the safety profile of the MF59 emulsion adjuvant.
6. Dosage Forms and Doses Reported in Studies
No regulatory body has established an official recommended daily intake for SLO as a dietary supplement. Doses used in clinical and research contexts include:
- In the surgical immunity study, patients were preoperatively treated with alkylglycerols at 500 mg twice a day for 4 weeks.
- Shark liver is a major natural source of alkylglycerols, which have no known side effects in dosages of 100 mg three times a day.
- Shark liver oil is possibly safe when used short-term. Doses of 1.5 grams daily have been used safely for up to 8 weeks.
- In a Japanese vascular safety study, a daily dose of the SLO capsule contained squalene at 582 mg in weight.
- One assessment suggested introducing the nutraceutical product in dosages of 500 mg twice a day to very old people before surgical treatment for modulation of leukocytes and soluble immune reactivity.
- In the Brohult cervical cancer studies, patients in the high-dosage subgroup received an average of 95 grams and the low-dosage subgroup received an average of 65 grams of alkylglycerols total over the course of the radiation treatment period.
Based on the lack of clinical trials in humans, hard evidence for shark liver oil effectiveness for any condition whatsoever is currently in short supply. Likewise, there are no formally established dosages for shark liver oil.
7. Safety Considerations and Interactions
7.1 General Safety Profile
Few toxic effects have been reported. SLO supplements may have an unpleasant taste and/or odor. No adverse reactions or effects on mortality were noted in rats receiving short- and long-term doses of a supercritical fluid extract of SLO at doses 100 to 200 times that of normal human consumption.
7.2 Hepatotoxicity
A clinically notable adverse event has been documented in the literature. A case of acute toxic hepatitis was reported in a 31-year-old female who became symptomatic with malaise and abdominal discomfort 1 week after starting shark liver oil supplementation, which soon progressed to jaundice and pruritus. Upon admission, she had been taking shark liver oil capsules twice daily for 2 weeks. No family history, environmental, or infectious risk factors for hepatotoxicity were identified. Immediate improvement in symptoms was seen upon discontinuation of the supplement, with liver enzymes normalizing within 8 weeks.
7.3 Pulmonary Risk
There have been reports of SLO-induced pneumonia in humans and pigs. This risk appears to be associated with aspiration of the oil rather than oral ingestion.
7.4 Regulatory Actions
In Sweden, a SLO product (Ecomer) was prohibited for use by the National Board of Health and Welfare because of suspected adverse effects.
7.5 Environmental Contaminants
As an apex marine predator, sharks bioaccumulate environmental pollutants. As a marine product, shark liver oil may contain contaminants like mercury and PCBs (polychlorinated biphenyls). PCBs can have harmful effects in humans and may increase the risk of some types of cancer. However, though sharks are prone to heavy metal contamination — more specifically to mercury contamination — research suggests that it mostly accumulates in muscle tissue and fins, and when it comes to mercury-exposed fish, their oils tend to have negligible amounts of the metal, suggesting it may be removed during the manufacturing process.
Due to overfishing and increased pollution in the ocean — such as heavy metals and persistent organic pollutants — that can contaminate the triterpene product, shark-derived squalene is an unfavorable source for medical applications.
7.6 Vitamin A Toxicity Risk
Some SLO preparations, particularly from certain species, contain significant quantities of fat-soluble vitamins including vitamin A. In the bramble shark, for instance, oil was found to be a good source of fat-soluble vitamins A, D, and K (vitamin A: 17.08 mg/100 g of oil). Symptoms of vitamin A toxicity include dizziness, nausea, and, in severe cases, liver damage.
7.7 Lipid Profile Effects
Long-term use at high doses has been linked to changes in lipid profiles. Because squalene is a biochemical precursor to cholesterol synthesis, there is a risk of elevating total cholesterol and LDL cholesterol levels, which necessitates regular blood monitoring for frequent users.
7.8 Drug Interactions
SLO has a high omega-3 content, which is known to lower blood pressure. Similarly, given the blood-thinning effect of omega-3 PUFAs, its intake may increase the risk of bleeding when combined with blood-thinning drugs like aspirin and warfarin. Shark liver oil may also interact with certain medications, including blood thinners and immunosuppressants.
7.9 Oxidative Instability
Due to its omega-3 PUFA content, SLO is highly prone to oxidation, meaning that it may easily become rancid. Oxidized omega-3 supplements may lose their efficacy and lead to detrimental health effects. Factors that may cause SLO supplement to lose its freshness include exposure to light, heat, and oxygen.
7.10 Pregnancy and Seafood Allergy
Contraindications have not been formally identified. Information regarding safety and efficacy in pregnancy and lactation is lacking. People with seafood allergies may also react to shark liver oil.
8. Body Systems and Areas of Associated Use
- Immune system: Macrophage activation, enhancement of Fc-receptor mediated phagocytosis, humoral immune response modulation, haematopoiesis support.
- Oncology (adjunctive): Radioprotection during radiation therapy; mitigation of leukopenia and thrombocytopenia; anti-tumor and anti-metastatic activity in experimental models.
- Cardiovascular system: Potential anti-atherosclerotic effects via HMG-CoA reductase modulation; contradictory evidence on cholesterol and triglyceride levels.
- Skin and integument: Topical antioxidant protection, sebum component, moisturization, lipid peroxidation protection; component of dermatological and cosmetic preparations.
- Central nervous system (experimental): Blood-brain barrier permeabilization in experimental models for drug delivery.
- Respiratory and gastrointestinal systems: Traditional folk use for respiratory tract and digestive ailments.
- Lymphatic system: Historical use for lymphadenopathy.
- Pharmacology: Squalene is a key adjuvant component in licensed influenza vaccines (MF59, AS03, AF03).
References
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