This section is from the book "Practical Dietetics With Special Reference To Diet In Disease", by William Gilman Thompson. Also available from Amazon: Practical Dietetics with Special Reference to Diet in Disease.
Many substitutes for cod-liver oil have been proposed, but it is doubtful whether any of them can be made to yield all the benefits to be derived from the genuine substance.
Efforts have long been made to determine whether the alkaloidal or other substances obtainable from cod-liver oil do not possess all the nutritive and stimulating properties of the oil itself in equal or even greater degree. Some of them are doubtless capable of producing active symptoms, but if the oil itself is a true food, there can be no advantage in attempting to concentrate it beyond the minor consideration of avoiding its nauseous, fishy taste. M. Chapoteau describes a crystalline substance which he terms morrhuol, and which exists in the oil in the proportion of 1.5 to 6 per cent, the lesser quantity being found in the purest oil. It is claimed that three to five drops of this substance possess all the properties of a drachm of cod-liver oil. It may be given in capsules or disguised with olive oil, fat, or cream. Much interest is at present manifested in testing the clinical worth of preparations of this class, but although their use has been favourably reported by some observers within the past year or two, further evidence is required before their general substitution for the oil itself can be indorsed.
Von Mehring and Hauser recommend "lipanin," made by adding to olive oil 6 per cent of oleic acid. This is devoid of disagreeable taste and odour, and may be given in doses of from one to four teaspoonfuls three times a day.
Cod-liver oil is not a specific for any disease, and there are many clinicians who prefer to prescribe other forms of fat when possible. Fothergill wrote that "out of five persons taking cod-liver oil probably only two require fat in that particular form, while three take it because it is the only fat put up in such a form as can be readily purchased".
Nevertheless, there are often seen cases of phthisis in which a decided gain in weight follows the administration of a disproportionately small quantity of the oil. It is a most useful food in many conditions of debility, and is indispensable in the treatment of rickets and general tuberculosis.
It is found clinically to be of great service in a variety of forms of chronic inflammation and in cases in which there is old purulent discharge from any part of the body, as from the middle ear, or from a chronic abscess, like empyema, and in chronic bone diseases, such as caries.
Among other chronic diseases for which cod-liver oil is recommended may be mentioned chronic rheumatism and gout, arthritis deformans, a variety of skin affections, and advanced syphilis. It is of service also in pulmonary emphysema and in cases of chronic bronchitis with tenacious purulent expectoration, and by many it is believed to be of some specific value in loosening cough. It should be observed that oil when absorbed passes through the lymphatic system and is carried with tolerable directness into the pulmonary circulation, where fats in general are believed to be oxidised. It is suggested that this fact may possibly have some bearing on the influence attributed to cod-liver oil as an expectorant, although it seems more probable that the effect is derived from the improvement produced upon the general nutrition. Brunton attributes it to a stimulating action upon the epithelium of the bronchi. In cases of atonic dyspepsia, particularly among elderly people, cod-liver oil often relieves the "sinking " feeling at the epigastrium and the faint-ness of which they complain.
Ringer recommends cod-liver oil for vertigo in the aged which originates from feeble heart action, and for chronic endocarditis in children. It is also serviceable in relieving constipation in young infants, and it may be sometimes given with advantage in lieu of castor oil. Its loosening effect is more decided in children than in adults, and it is less likely to produce subsequent constipation than castor oil, besides being less disagreeable to take.
For marasmus the use of cod-liver oil is particularly indicated, and in infants when chronic diarrhoea obtains, some benefit may be derived from the topical application of the oil to the skin. To tuberculous children of the emaciated marasmic type in whom the skin is dry and wrinkled 15 or 20 drops of the oil may be given at night without fear of increasing the diarrhoea.