Patients with peritoneal disease commonly present with symptoms of abdominal distension and subacute intestinal obstruction. This results in poor oral intake leading to these patients often presenting in a malnourished state.

CRS and HIPEC can potential provide improve survival for these patients, however can be a hazardous procedure, involving multi-organ resections. The risk is especially high in poorly nourished patients.

The study investigators hypothesize that perioperative immunonutrition can reduce wound infections and length of hospital stay, and improve perioperative outcomes. To the investigators' knowledge, it has not been evaluated in patients undergoing CRS and HIPEC.

Inclusion Criteria:

1. All patients planned for CRS and HIPEC, with sufficient time (5 to 7 days) prior to surgery for start of nutritional supplements are eligible
2. All patients must be able to provide informed consent
3. There are no restrictions to use of contraception

Exclusion Criteria:

1. Patients who are not able to provide informed consent will be excluded.
2. Patients with a diagnosis of diabetes mellitus will be excluded.
3. Patients not fit for surgery or those who undergo surgery under emergency situations will be excluded.
4. Patients who have intestinal obstruction and not able to consume the nutritional supplements orally will be excluded.

The investigators and the clinical team which manages the patient, will be blinded.