Evolution of parenteral lipid emulsions

Lipid emulsions can be used as a parenteral source of essential fatty acids (FA), fat-soluble vitamins and energy. The evolution of parenteral lipid emulsions may be divided into three generations of products and concepts. The first generation is represented by conventional lipid emulsions based on soybean and/or safflower oil, very rich in o-6 polyunsaturated fatty acids (PUFA). These pioneering lipid emulsions were developed by a group of scientists under the guidance of Dr. Arvid Wretlind who managed to demonstrate a good correlation between the outcomes in both experimental studies and clinical trials. The second generation of parenteral lipid emulsions was developed in response to indications of the potential disadvantageous effects of the high levels of PUFA present in the previous generation of lipid emulsions. Critical evaluation indicated that an excessive intake of o-6 PUFA in parenteral nutrition was associated with an unbalanced FA pattern in cell membranes, which may lead to a modification of the production of lipid mediators (prostaglandins and leukotrienes) and a promotion of immunosuppression and systemic inflammatory reactions (trauma, surgery and sepsis). At the experimental level we could show a decreased phagocytosis by liver and lung resident macrophages of rats treated with total parenteral nutrition containing o-6-PUFA-rich lipid emulsions. We also found a decreased bacterial killing function