Bovine lactoferrin (bLF) and human lactoferrin (hLF) have high (77%) amino acid homology, with bLF exhibiting even higher in vitro antimicrobial activity than hLF.5 Bovine lactoferrin has been granted GRAS (generally recognized as safe) status by the US Food and Drug Administration [12] and on this basis is added to infant formula by many manufacturers with no reported adverse effects. Despite many promising in vitro and animal experimental data, clinical information on bLF is scarce, with no studies investigating the effects of bLF supplementation in patients with prolonged mechanical ventilation.