Invited Commentary

Parenteral nutrition (PN) is one of the greatest inventions in modern medicine. With PN, certain patient populations who cannot tolerate or receive enteral nutrition (EN) are given a good chance to survive because progressive malnutrition can be avoided. Without PN, many advances in surgery and critical care, on which we physicians today rely, would never have been realized. Nevertheless, because of its nonphysiological properties, a number of PN-induced changes have been clinically and experi-mentally observed, and some of these changes can even be life-threatening.1,2 The best way to avoid a PN-associated adverse event is to deliver nutrients via the gut. The higher the ratio of EN to PN, the more restoration of gut immunity can be expected.3 However, we prescribe PN for patients because they cannot tol-erate EN. We need other alternatives to EN to preven