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Lipid emulsion is an integral component of total parenteral nutrition (TPN). Not only are these emulsions a valuable calorie source but they also provide a supply of essential fatty acids. Children have large energy requirement to grow up, so energy supply with lipid emulsions is especially important in children. But, it is supposed that lipid emulsions suppress the immune function and there has been controversy about the effect of lipid emulsion on immune system. The reluctancy to administer lipid emulsion as well as no lipid emulsion administration for long period has been observed in our hospital because it has been suggested that lipid emulsions possess immunosuppressive properties. This review analyzes the effect of lipid emulsion on immune system. For this purpose, we reviewd 25 relevant studies. Studies on the effect of lipid emulsion on polymorphonuclear (PMN) cell, lymphocyte, monocyte or macrophage have been evaluated. The studies that show lipid emulsions cause an impairment of PMN cell and lymphocyte function were most in vitro studies. And many of these studies have been performed under highly artificial condition in which the dose of lipid emulsion has been inappropriate to clinical practice. In vivo studies show that lipid emulsions no effect on PMN function or enhance the function of PMN on the contrary. The studies that investigate the effect of lipid emulsion on lymphocyte showed conflicting results. Ota et al were unable to detect significant immunologic changes following lipid emulsion infusion. Conversely it has been observed that following a course of preoperative lipid-based TPN in patient with cancer of gastrointestinal tract lymphocyte function was impaired. But, these studies performed in gastrointestinal cancer patient who have already depressed lymphocyte function and chose lipid-based regimen in which lipid emulsion provided more than a half of calorie. In the studies that show lipid emulsion have no immunosuppressive effects, lipid was administered in a rate or dose less than maximum recommended rate or dose. From the studies reviewed, it can be deduced that lipid emulsion do not supress immune system when administered in the recommended dosage.
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