Parenteral Lipid Tolerance and Adverse Effects: Fat Chance for Trouble?

Lipid emulsions (LEs) are indispensable sources of fuel calories and (essential) fatty acids (FAs) in modern parenteral nutrition formulations. The use of LE, however, also remains associated with the development of adverse effects. Intolerance for LE mostly becomes apparent upon the development of patient complaints or disturbed blood function tests, mainly of the liver. These issues may be associated with the composition, stability, or the infusion rate of the emulsion. Also, altered balances of (anti)oxidants or the presence or absence of protective or toxic bioactive agents such as phytosterols and tocopherol in LE may lead to complications, especially in already vulnerable patients with an inflammatory condition. While the oldest available LEs are based on pure soybean oil (SO-LE), rich in the proinflammatory ω-6 polyunsaturated fatty acid linoleic acid, more recent next-generation LEs where alternative FA sources such as olive and fish oil (partially) replace soybean oil to lower the content of linoleic acid seem safe and effective. Especially LEs containing fish oil (FO-LE) have less proinflammatory characteristics that promise to convey beneficial effects on immune system and organ functions, although much of the available evidence awaits more robust clinical validation.