Invited Review: Development of Fat Emulsions

The studies on the possibility of preparing IV fat emulsions began in the 1920's; since then, a very large number of emulsions with various fats and emulsifiers have been investigated. However, none of the early fat emulsions could be used safely in man. By the trial and error technique, a method was finally found to prepare soybean oil and egg yolk phospholipids to make a fat emulsion that had a low incidence of adverse reactions. A newly devised biological test system based on nutritional concepts was of crucial importance. It meant that any energy supplying nutrient should be tested in animals in relation to the energy requirement of the species used and not identical to the human dose/kg body weight as in the "classical" toxicity and tolerance tests. With the development of well-tolerated IV fat emulsions it has been possible to devise a TPN regimen that is adequate from a nutritional point of view as well as an adequate alternative to the ordinary oral food. This regimen, which can be administered by the peripheral route, means that the original aims for developing IV fat emulsions were finally achieved.