[Use of unconventional lipid substrates in parental nutrition]

In addition to the classic soybean oil fat emulsion, developed more than 40 years ago and still widely used, emulsions with other lipid substrates are available today for parenteral nutrition; these substrates implement the benefits offered by soybean oil when mixed with it in given proportions. Soybean oil triglycerides are rich in linoleic acid, a long chain omega-6 polyunsaturated fatty acid, which is essential and is an indispensable component of parenteral nutrition. However, very high doses of omega-6 polyunsaturated fatty acids should be avoided, particularly in some critical illnesses. Medium chain triglycerides, long well known to nutritionists and dietitians for their easy intestinal absorption, have become available in parenteral nutrition emulsions in a mixture with soybean oil. Medium chain triglycerides are completely and readily used for energy production and do not interfere significantly in the production of inflammatory mediators, in the composition of cell membranes and in body organ and system functions. Omega-3 polyunsaturated fatty acids, essential fatty acids derived from fish oil, permeate cell structure and affect cell activity with different mechanisms, playing also an important role in the modulation of inflammatory processes. Omega-3 emulsions in parenteral nutrition are currently added as a supplement to other fat emulsions. Knowledge of these "non-conventional" fat emulsions is being continuously improved by investigative work and clinical experience.