The overall objective of this proposal is to explore the association between the administration of the prebiotics GOS (trade name: Bimuno Travelaid; generic name:B galacto-oligosaccharides) with pain, anxiety, and cognitive function in the perioperative period. The investigators' central hypothesis is subjects who consume GOS in the perioperative period will demonstrate lower levels of salivary cortisol before, during, and after their operative procedures. In addition, the investigators expect subjects who consume GOS to have lower perceived levels of anxiety during the perioperative period. Finally, the investigators hypothesize that subjects who consume perioperative GOS will perform better on tests of cognition in the postoperative period. Such a finding would be beneficial in that administration of GOS in the perioperative period offers a safe and inexpensive adjunct to current medical management of perioperative anxiety.