49; 95% CI, 0.30–0.83; p < 0.01) and LOS (mean difference −2.22; 95% CI, −2.99 to −1.45; p < 0.01). There was no statistically significant reduction in noninfectious complications (OR = 0.81; 95% CI, 0.53–1.23; p = 0.32) or wound infections (OR = 0.69; 95% CI, 0.43–1.10; p = 0.12) (Fig. 3). This meta-analysis demonstrates no significant difference in effect of preoperative IN as compared with standard ONS on postoperative clinical outcomes. Given the high costs, poor palatability, and limited retail

availability of IN products, standard ONS can be a reasonable preoperative alternative. Standard ONS are inexpensive, widely available, and manufactured by multiple vendors in a variety of flavors to suite various tastes. Given the heterogeneity of the DAPT existing IN literature, the precise role of preoperative IN has not been clearly defined. Our results suggest that preoperative standard ONS is similar to IN. The literature for postoperative IN is much stronger. Postoperative IN has been demonstrated in many trials and several meta-analyses to reduce infectious complications, ventilator

days, and anastomotic leaks.4, 24, 25, 26, 27, 28 and 29 The theoretical grounding for IN is strong, particularly in concert with an early enteral feeding algorithm.30 Arginine, one of the key components of an IN strategy, is rapidly depleted in surgery and after major metabolic stresses.6 Supplementation can promote cell growth and differentiation and microvascular perfusion in these patients. Omega-3 fatty acids in several mTOR inhibitor Selleckchem CHIR 99021 perioperative randomized trials have been demonstrated to modulate proinflammatory and anti-inflammatory mediators in the heart, gut, liver, and in tumor tissue.31, 32, 33 and 34 Antioxidants are typically the other key ingredient

in IN products. Preoperative antioxidants have been shown to increase serum and tissue antioxidant levels, but the clinical benefit is unclear.35 Because these are combination products, it is challenging to sort out the effects of the various ingredients. The literature suggests the synergism of effects by combining distinct immune-modulating nutrients, especially arginine and fish oil. Several other investigators have performed meta-analyses examining various aspects of perioperative IN. Existing literature has often blurred the lines between preoperative, postoperative, and perioperative (pre- and post-) regimens.36 Many preoperative IN studies do not use isocaloric or isonitrogenous controls.37 Only one preoperative trial has ever demonstrated a statistically significant reduction in infectious complications when IN is compared with an isocaloric, isonitrogenous control oral supplement.11 This trial and two others without isonitrogenous controls also published by the same group in the same year are responsible for much of the signal of benefit detected in multiple previously published meta-analyses.