Bacterial Intestinal Gut Modification Around Cancer Surgery (BIG MACS) Diet

Inclusion criteria

• Age 25-70 years
• Primary diagnosis of colon cancer, stages 1-3.
• Able and willing to provide informed consent.
• English-speaking.
• Willingness to return to the study site for specified study visits at D7 and D30.
• Able to comply with study measures.

Exclusion criteria

• Age ≤ 25 years or ≥70 years
• If surgery is being performed for any reason other than resection of colon cancer. Neoadjuvant therapy, or if surgery is not the initial approach for the patient's colon cancer treatment
• Significant anemia (hemoglobin 1.0 g/dL or more below normal range) or history of coagulopathy: any personal history of hereditary or acquired bleeding disorder, or thrombocytopenia with platelets under 100,000.
• Serum creatinine greater than 1.5 mg/dL.
• Serum total bilirubin greater than the upper limit of normal in the absence of Gilbert's syndrome or alkaline phosphatase or ALT or AST greater than 2.5 times the upper limit of normal. Elevated INR (1.5 or above).
• Alcohol intake more than one drink or greater than 20 grams per day for women or 30 grams per day for men.
• History of gastrointestinal surgery including stomach, small bowel or colon resection, pancreatic surgery, bile duct or gallbladder surgery, or splenectomy, or gastric bypass.
• History of intra-abdominal sepsis.
• Previous organ transplantation.
• Self-reported HIV-positive status, active tuberculosis, active malaria, chronic hepatitis B or C, cirrhosis, or inflammatory bowel disease.
• Currently pregnant or nursing.
• History of alcohol, drug, or opioid dependency (excluding nicotine) in the past five years.
• Active psychosocial or psychiatric problem that is likely to interfere with adherence to the protocol.
• Depression: A CES-D score more than 16 and a psychologist determining that the patient is not a good fit for surgery.
• Body mass index (BMI) <20 or > 40 kilograms per meter squared:

obesity is known to impact the microbiome and immune system and the occurrence of anastomotic leak, and extreme obesity may confound interpretation of these factors in association to leak. Inferences may be made by matching participants with less severe obesity (BMI <40).

• Presence of any type of non-MRI compatible implant, including cardiac pacemakers or defibrillators, neurostimulators, cochlear implants, or other metallic hardware
• Self-reported history of claustrophobia.
• Incarceration
• Inability to adhere to the study protocol, procedures, and diet
• Exclusions may also be made at the discretion of the attending physician.