Cod Liver Oil

COD LIVER OIL (Oleum Jecoris Aselli). In medicine, this name refers to the liquid fat obtained from fresh liver of cod Gadus morrhua L., as well as from Gadus callarias L., Gadus aeglefinus L., family Gadidae. C.L.O. was proposed by Percival in England in 1782 for the treatment of chronic rheumatism; it came into wide use only from 1822 on the recommendation of Dr. Schenk. From a medical point of view, two grades of C.L.O. are distinguished: 1) Ol. Jecoris Aselli album or Virginum—the best, highest grade, pale yellowish colored, transparent, liquid with a characteristic smell and taste, specific weight 0.920-0.932, difficult to dissolve in alcohol, easily in ether, chloroform and carbon disulfide; dissolves in 2.5 parts of acetic ether. When stored it does not become cloudy, belongs to semi-drying oils. 2) Ol. Jecoris Aselli flavum—yellow C.L.O. with a less mild taste and more pungent smell. Both grades are obtained from the liver of just caught and eviscerated fish, at which time the liver is freed from the gall bladder, thoroughly washed and sorted: full, fatty, almost white liver is used for obtaining medical fat. For this purpose, selected livers are placed in high tinned metal vats, heated at a temperature not exceeding 50°; the fat is thereby rendered and displaced by the pressure of the livers placed one on top of another. In this way the highest quality fat is obtained. In order that hydroxy acids do not form in the C.L.O. during its displacement and rendering from the livers, the entire process of obtaining the fat is carried out without access of air in a vacuum apparatus or in an atmosphere of carbon dioxide. To obtain the second grade of C.L.O., mechanical pressing is used with gradual somewhat stronger heating, however not above 85°, in order to obtain thereby a larger quantity of C.L.O. The processing of high grades of C.L.O. concludes with settling the obtained fat (whereby suspended and emulsified substances in it precipitate) and cooling at a temperature from -5° to -10°, from which solid masses (solid glycerides) precipitate from the C.L.O., removed by subsequent filtration of the fat. Settling, freezing out and filtering subsequently ensure the complete transparency of the best grade of C.L.O. even during long storage. C.L.O. is produced in the largest quantities by factories in Norway, from where it is transported through Bergen for almost all of Europe. C.L.O. is also obtained in Iceland, Scotland, Newfoundland, Labrador, Japan, in the USSR in Murmansk and the Far East. Lower grades of C.L.O.—dark colored and odorous—are usually used for technical purposes—for the manufacture of lubricants, leather processing, lubrication of machine belts, in rope factories, as lamp oil, etc. In trade, lower grades of C.L.O. are known under various names—brown C.L.O., peasant, barrel, etc. Some of these grades are obtained by pressing with strongly heated presses from cut and boiled in water residues of livers already used for obtaining medical C.L.O., and also are obtained from lean livers, as well as from livers that have lain and even partially rotted and spoiled. Some grades of C.L.O. are almost black in color, resembling whale oil. In exceptional cases, the use of brown C.L.O. for therapeutic purposes can still be seen. The properties and composition of high-grade C.L.O. depend partly on the place where the fat is obtained and mainly on the methods of obtaining and processing. In natural C.L.O. the iodine number varies from 135 to 180. According to Ph VI, the limits for iodine number are given as 150-175, for saponification number 184-196, and for acid number—not more than 2.81. Ph VI requires that there be no admixture of any foreign mineral and vegetable oils, as well as heavy metals in C.L.O. In official C.L.O. the most (approx. 70%) is triolein, somewhat less (25%) tripalmitin, a little tristearin and trimyristin, as well as very small amounts of glycerides of acetic, butyric, valerianic, capric, azellic and heptadecanoic acids. A small amount of acids is present in C.L.O. in the free state, determining its acidity. In C.L.O. from 0.3% to 0.6% cholesterol, a little coloring substance, so-called lipochrome (these substances give the Liebermann, Salkowski, etc. reactions); from 0.0002% to 0.0003% iodine and some amount of bromine, chlorine, phosphorus and sulfur in the form of organic compounds. Ammonia and amines—trimethylamine, butylamine, amylamine and hexylamine—are also components of C.L.O.; in higher grades there is very little of them; They determine the "fishy smell" of the fat (E. Schmidt). In red or yellow C.L.O. there are alkaloid-like bodies in an amount of about 0.04%: azellin, C₂₅H₃₂N₂O, amorphous, almost insoluble in water, flaky powder; morruin, C₁₉H₂₇N₃O, thick, yellow, difficult to dissolve in water oil; dihydrolutidine, C₇H₁₁N, easily soluble in water, boiling at 199°, strongly alkaline, poisonous liquid; morruinic acid, yellow mass, difficult to dissolve in water, easily in alcohol (E. Schmidt). In C.L.O. there are significant amounts of fat-soluble vitamins (vitasterins) A and D. Their presence is explained by the fact that cod as a predatory fish feeds on small fish and lower forms of marine animals, for which food serves marine algae, producing the said vitamins from sterols under the influence of intense insolation during the polar summer. Modern clinicians and researchers attribute the active therapeutic properties of C.L.O. to its richness in these vitasterins, especially in rickets, for which C.L.O. has long been used. The favorable therapeutic effect of C.L.O. in rickets, osteomalacia, anemias on the basis of exhaustion, after severe illnesses, in bone tuberculosis, in night blindness was until recently explained by its nutritional value as a fat that is easily absorbed, assimilated and easily burned. This view found its justification in the old (1875) research of Buchheim and in the assertions (1883) of Schmiedeberg that C.L.O. for nutrition has only the same significance as any other digestible fat, why C.L.O. should be considered only as a nutritional agent. Poulsson in 1920 calls C.L.O. a "nutrient agent", denies that C.L.O. belongs to medicinal substances in the usual understanding of such. The works of Bier and his colleagues regarding the therapeutic effect of small doses of iodine and the much developed question of the anti-xerophthalmic vitamin A and the anti-rachitic vitasterin D give full right to consider C.L.O., besides its nutritional value, a very valuable and specific medicinal agent, possessing scientifically established specific therapeutic action, depending on the presence of vitasterins A and D (see Vitamins) and iodine (see). Under the influence of vitamins, the body's ability to assimilate calcium as well as phosphorus is significantly enhanced. C.L.O. is prescribed to patients during their recovery period after acute and chronic diseases, in anemias on the basis of general exhaustion after severe diseases, in scrofula, rickets, osteomalacia, xerophthalmia, night blindness, bone tuberculosis, etc. C.L.O. is taken internally per se by teaspoon or tablespoon two to three times a day in the intervals between meals, but not on an empty stomach, in order not to cause disorders of the gastrointestinal tract. C.L.O. should not be given immediately after meals, as is very common. Pieces of food are enveloped in fat and this hinders their processing in the stomach by digestive juice (Poulsson). Treatment with C.L.O. is usually carried out in cold weather, in order to avoid rancidity or oxidation of this agent and thus cause intestinal disorders. The yellow (red) C.L.O. is less well tolerated by the intestine, since it contains more free acids (4-6%), and in addition there are also alkaloid-like substances. Catarrhal diseases of the stomach and intestines are a contraindication to the use of C.L.O. The assertions that yellow or red C.L.O. has a more active effect due to its higher iodine content are not justified. 42 f Some patients do not tolerate C.L.O. (idiosyncrasy); others take it very reluctantly because of taste sensations and smell. In such cases, patients are advised to rinse their mouth with water before taking C.L.O., and to moisten the spoon with water beforehand, after which to pour the fat into it; one can add fruit juices to C.L.O. for flavor and taste, or add sugar and a little essential peppermint or lemon oil; very often the taste and smell of C.L.O. is successfully masked if the patient after taking C.L.O. eats a piece of black bread or drinks coffee. Wine or beer should not be given to mask the taste of C.L.O. Children usually quickly get used to C.L.O. and drink it willingly. For severely exhausted children, C.L.O. can be given 20.0-30.0 daily, gradually reaching this amount from 4.0-5.0. Parenteral use of C.L.O. (Nikolayshvili) requires further study. C.L.O. is quite often prescribed in the form of a regular emulsion for internal use.

In addition, a large number of emulsions are prepared from C.L.O. according to special recipes, with the aim of providing the C.L.O. in a form that ensures a pleasant taste and odor, or to introduce into the emulsions with C.L.O. medicinal substances insoluble in C.L.O. but soluble in water—calcium, phosphorus, iodine, iron, pepsins, pancreatin. In Hager's manual, a large list of such recipes is given, which apparently is based on the idea of the extraordinary healing properties of C.L.O. due to its property of forming an easily emulsified, rapidly absorbed mass. It should be taken into account that in the form of emulsions, C.L.O. is significantly more susceptible to oxidation and spoilage; to prevent bacterial spoilage in emulsions intended for long-term storage, antiseptics are added. When creating pharmaceutical forms from C.L.O., it must be kept in mind the presence of vitamin sterols in the fat and their relationship to the added medicinal components. This is a large and complex issue, still only beginning to be developed. The annual demand of the USSR for official C.L.O. is not less than 1,200 tons. As a substitute for C.L.O. for therapeutic use, dolphin oil is permitted, which is obtained on our Crimean coast. Clinical observations on the therapeutic effect of dolphin oil (Levit and Mikhailina) establish that the use of this oil in rickets gives a positive result. For a final decision on the therapeutic properties of dolphin oil, research on its chemical and physical properties is being conducted. As a substitute for C.L.O., seal oil is also proposed; among artificially obtained substances, it is necessary to mention irradiated or activated ergosterol (vigantol); Poulsen (1931) points out that vigantol does not contain vitamin A, whereas in C.L.O. it is present and, together with vitamin D, often has a synergistic effect. In addition, it is noted (Avellar) that vitamin A of fish oil and vitamin D of irradiated ergosterol are not identical. The term 'fish oil' in a broader sense refers to the fat found and obtained from every well-fed fish, and not only to cod liver oil. These fats (except for the mentioned fats of marine animals) have not been studied and one cannot, without studying their vitamin value, consider them in general replaceable by medical fish oil.