The goal of this prospective randomized double-blinded bi-national study is to test the prophylactic effect of polyacetylenes from carrots on the population of patients who had a resection of high-risk adenomas of the large bowel.

The main question it aims to answer is: Will carrot juice rich in polyacetylenes inhibit neoplastic transformation and growth in high-risk humans?

Participants will have to drink 100 ml of juice daily after the adenoma resection for 1 year and keep a simple diary/calendar.

Researchers will compare the group with ingestion of Falcarinol (FaOH) / Falcarindiol (FaDOH) rich carrot juice versus the group consuming placebo juice, to see if the polyacetylenes significantly reduces neoplastic transformation and growth in high-risk patients.

The study is a prospective double-blinded randomized controlled trial carried out in four centers: one Danish (Department of Surgery, Odense University Hospital - OUH) and five Swedish (Ersta Hospital - EH, Stockholm; Karolinska University Hospital - KUH, Stockholm; Uppsala University Hospital - UUH, Uppsala; Sahlgrenska University Hospital - SUH, Goteborg, Capio St. Gorans Hospital - CSH, Stockholm).

The investigators will organize two parallel arms of 400 patients: an intervention arm (consumption of 100 ml active carrot juice daily) and a control arm (consumption of 100 ml placebo juice daily) in a 1:1 randomized allocation ratio for 1 year. The project is structured in 2 working packages (WP):

1. The clinical trial (including cultivation and quality control of carrots and juice production; quantification of FaOH and FaDOH in the carrot and the placebo juice and the randomized trial)
2. The assessment of patient compliance and ways to improve it (Umeå Institute of Design, Umeå University - UMU).

The investigators hypothesize that the difference between the active arm (carrot juice) and the control arm (placebo juice) measured by number and growth rate (size) of recurrent adenomas will mediate a 20% reduction or larger in both size and number.

Outcomes will be investigated through standard colonoscopy report, questionnaires, calendars and diaries.

The randomization is stratified by inclusion center, each having its own block of 50/50 distribution between active and placebo arm.

The patients will collect 8 L of juice, the diary, calendar and a questionnaire every 2 months. At this meeting the patients will also have a follow-up discussion with the project nurse.

All patients will undergo colonoscopy after one year from the resection and in addition, for the piecemeal resections there will also be a local follow up colonoscopy after 6 months. Information about recurrence, the number of polyps, polyp size and characterization will be registered in the database. Full compliance is defined as consumption of > 75% of the juice delivered. Consumption data for all patients will be kept for compliance analysis.

Data will be analyzed using exact methods for binomial data. The combined endpoint will be the total number of recurrent adenomas multiplied with mean size of recurrent adenomas in the relevant treatment group.

Participation is voluntary with no economic compensation, and the patients are informed orally and in writing according to the information accepted by the ethics committee.

Inclusion Criteria:

1. Any type of resection for adenomas larger than 20 mm in size (endoscopically evaluated) or endoscopically resected T1 cancers.
2. Acceptance of the treatment and follow-up program.
3. Capability to understand and follow the instructions.

Exclusion Criteria:

1. Patients allocated to "high-risk" group because of many small polyps (>4).
2. Pregnancy.
3. Known relevant allergies.
4. Chronic consumption of COX (cyclooxygenase) inhibitors (Aspirin, Celecoxib, Ibuprofen, Diclofenac, Ketoprofen, Ketorolac, Indometacin, Naproxen, Piroxicam) or immunosuppressive agents (Methotrexate, Azathioprine or glucocorticoids).
5. Patients with different neoplastic disease under treatment (Chemo-/Radio-/Imunotherapy).
6. Severe comorbidity NYHA III-IV.
7. Lynch syndrome.