Shark Liver Oil
Scientific Name(s):Shark liver oil may be obtained from several species of sharks, including the deep sea shark ( Centrophorus squamosus ), the dogfish shark ( Squalus acanthias ), and the basking shark ( Cetorhinus maximus ).
Clinical Overview
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Uses of Shark Liver Oil
SLO has been used to prevent radiation sickness, to treat skin conditions, and as a cancer treatment. Alkylglycerols have been studied as an immune system stimulant.
Shark Liver Oil Dosing
Shark liver oil marketed under the name isolutrol has been studied in a clinical trial of acne at a topical concentration of 0.15 g/100 mL.
Contraindications
Contraindications have not yet been identified.
Pregnancy/Lactation
Information regarding safety and efficacy in pregnancy and lactation is lacking.
Shark Liver Oil Interactions
None well documented.
Shark Liver Oil Adverse Reactions
Few toxic effects have been reported; advise caution with SLO concerning SLO-induced pneumonia.
Toxicology
In Sweden, a SLO product ( Ecomer ) was prohibited by the National Board of Health and Welfare.
Shark liver oil (SLO) is commercially produced from several species of deep sea sharks' liver oil. The liver constitutes about 25% of the total shark body weight. SLO is a major natural source of squalene and alkyglycerols. 1
History
SLO has been used for over 40 years for its therapeutic benefits. Initially, it was employed by Scandinavian fishermen to treat skin conditions and certain cancers. The active components, alkylglycerols, have been studied in a number of areas, including use as an immune system stimulant. 2
Chemistry
SLO contains alkylglycerols, squalene, pristane, vitamins A and D, esters of fatty acids, glycerol ethers, triglycerides, cholesterol, and fatty acids. 1 Alkylglycerols are a group of ether-linked glycerols and have been found in a number of shark species. For example, 1-O-(2-hydroxyalkyl) glycerols have been isolated from Greenland SLO. 3 Dogfish shark contains 40% to 70% SLO, containing 30% to 40% 1-O-alkyl diacylglycerol ethers. 4 Purification and characterization of deep sea shark liver oil 1-O-alkylglycerols have been performed. The oil contained glycerol esters, 60% unsaponifiable matter, including squalene (45%) and cholesterol (4.5%). 5 Between ≈ 60% to 90% of liver weight in the Centrophorus species is oil, containing squalene that increases in concentration with the age of the shark. More than 50 fatty acids were identified, as well. 6
Analyses of shark liver components from the late 1960s through the early 1970s include the following: Oil composition of the basking shark including sterols and glyceryl esters, 7 , 8 separation of neutral lipids from shark liver, 9 and hydrocarbon and fatty acid research. 10 , 11
Shark Liver Oil Uses and Pharmacology
CancerAn early use of alkylglycerols from SLO was to treat leukemia and to prevent radiation sickness from cancer X-ray therapy. 2 Another report suggests alkylglycerols' radioprotective effects may operate by a mechanism that may incorporate the substance into a pool of platelet-activating factors, increasing their biosynthesis. 12 Another effect of alkylglycerols include the ability to stimulate the immune system. One mechanism involved may include activation of macrophages. 2
Animal dataThe natural alkylglycerol level rises within tumor cells, apparently an attempt in controlling cell growth. An essential step in cell proliferation involves activating protein kinase C, which can be inhibited by alkyglycerols. SLO demonstrates inhibitory actions against cutaneous angiogenesis in certain cancer cells in mice. 13
Clinical dataA Danish study reports less cases of irradiation damage in alkoxyglycerol-treated uterine cancer patients. 14 Alkoxyglycerol also may increase leukocyte and thrombocyte counts in specific dosages. 14 However, a conflicting report finds no documentation regarding inhibition of tumor growth in alkoxyglycerol-treated cancer patients, even though it is used in Denmark as a supplementary agent in cancer treatment. 14
SLO demonstrates inhibitory actions in human kidney cancer, and human urinary bladder cancer cells including sarcoma L-1 syngeneic. 15
Other usesSLO has been classified as a topical protectant. 1
Dietary SLO also has been studied for its effects on lipid and fatty acid composition in guinea pig hearts. 15 A glycerol monoether mixture from SLO was found to be an effective skin penetration enhancer when studied in mice. 16
Dosage
Shark liver oil marketed under the name isolutrol has been studied in a clinical trial of acne at a topical concentration of 0.15 g/100 mL. 17
Pregnancy/Lactation
Information regarding safety and efficacy in pregnancy and lactation is lacking.
Interactions
None well documented.
Adverse Reactions
It has been stated that SLO has no side effects in dosages of 100 mg three times daily. 2 However, a report on SLO-induced pneumonia in pigs is described, 18 as well as a case report concerning shark oil pneumonia. 19
Toxicology
In Sweden, a SLO product ( Ecomer ) was prohibited by the National Board of Health and Welfare. 20
Bibliography
1. Budavari S, et al, eds. The Merck Index, 11th ed. Rahway NJ:Merck and Co., 1989.2. Pugliese P, et al. Some biological actions of alkylglycerols from shark liver oil. J Altern Complement Med 1998;4(1):87-99. Review.
3. Hallgren B, et al. 1-O-(2–hydroxyalkyl) glycerols isolated from Greenland shark liver oil. Acta Chem Scand B 1974;28(9):1074-76.
4. Kang S, et al. Digestion of the 1-O-alkyl diacylglycerol ethers of Atlantic dogfish liver oils by Atlantic salmon Salmo salar. Lipids 1997;32(1):19-30.
5. Bordier C, et al. Purification and characterization of deep sea shark Centrophorus squamosus liver oil 1-O-alkylglycerol ether lipids. Lipids 1996;31(5):521-28.
6. Peyronel D, et al. Fatty acid and squalene compositions of Mediterranean Centrophorus SPP egg and liver oil in relation to age. Lipids 1984;19(9):643-48.
7. Lombardi R, et al. Analysis of ointments, oils, and waxes. X. Study of the composition of oil of basking-shark, Cetorhinus maximus Gunner. Ann Pharm Fr 1971;29(7):429-36. French.
8. Nevenzel J. Basking shark liver oil sterols and glyceryl ethers. UCLA-12-686. UCLA Rep 1968;Jun 30:16-18.
9. Casey A. Separation of neutral lipids of shark liver by “dry-column” chromatography. J Lipid Res 1969;10(4):456-59.
10. Gelpi E, et al. Gas chromatographic-mass spectrometric analysis of isoprenoid hydrocarbons and fatty acids in shark liver oil products. J Am Oil Chem Soc 1968;45(3):144-47.
11. Blumer M. Hydrocarbons in digestive tract and liver of a basking shark. Science 1967;156(773):390-91.
12. Hichami A, et al. Modulation of platelet-activating-factor production by incorporation of naturally occurring 1-O-alkylglycerls in phospholipids of human leukemic monocyte-like THP-1 cells. Eur J Biochem 1997;250(2):242-48.
13. Skopinska-Rozewska E, et al. Inhibitory effect of shark liver oil on cutaneous angiogenesis induced in Balb/c mice by syngeneic sarcoma L-1, human urinary bladder and human kidney tumour cells. Oncol Rep 1999;6(6):1341-44.
14. Hasle H, et al. Shark liver oil (alkoxyglycerol) and cancer treatment. Ugeskr Laeger 1991;153(5):343-46. Danish.
15. Murphy M, et al. Diets enriched in menhaden fish oil, seal oil, or shark liver oil have distinct effects on the lipid and fatty-acid composition of guinea pig heart. Mol Cell Biochem 1997;177(1–2):257–69.
16. Loftsson T, et al. Unsaturated glycerol monoethers as novel skin penetration enhancers. Pharmazie 1997; 52(6):463–65.
17. Dunlop KJ, Barnetson RS. A comparative study of isolutrol versus benzoyl peroxide in the treatment of acne. Australas J Dermatol . 1995;36:13-15.
18. Seo J, et al. Shark liver oil-induced lipoid pneumonia in pigs: Correlation of thin-section CT and histopathologic findings. Radiology 1999;212(1):88–96.
19. Asnis D, et al. Shark oil pneumonia. An overlooked entity. Chest 1993;103(3):976-77.
20. The National Board of Health and Welfare prohibits Ecomer. Shark liver oil is suspected of adverse effects. Lakartidningen 1990;87(7):473. Swedish.
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