Dietary intervention with UNICLA-A2 milk products containing beta casein A2 protein, and higher levels of omega-3 fatty acids and selenium may contribute to maintain the intestinal integrity, reduce inflammatory processes, normalize the immune system, protect against oxidative damage and equilibrate the gut microbiota in high-risk colorectal cancer patients who have undergone polypectomy

Colorectal cancer (CRC) is one of the most frequent cancers in the world and has a significant impact in terms of mortality and health costs. It is estimated that CRC causes around 900,000 deaths annually, mainly due to diagnoses made in advanced stages. Colorectal adenomas (CRA) are precancerous lesions that develop into colorectal cancer following a well-known process into the adenoma-carcinoma sequence. Prevention programs include screening for CRA and removing precancerous lesions by polypectomy, but the high recurrence rates after polypectomy makes it necessary to research on potential chemopreventive agents that may reduce this risk. Dietary recommendations or chemoprevention with different nutritional substances (diets rich in fiber, or poor in red meat, etc) or pharmacological substances including vitamin D, calcium, fatty acids, salicylic acetyl acid, nonsteroidal anti-inflammatory agents (NSAIDs), etc) have been studied. In this way, it seems reasonable to evaluate the effect caused by the administration of certain nutrients that affect lipid and protein metabolism involved in cellular homeostasis, in the preservation of the colonic mucosa or the development of lesions may have in populations at risk.

UNICLA A2 dairy products have a different nutrient profile than conventional ones. UNICLA A2 products have higher content in unsaturated fats, that is to say, increased content of healthy fatty acids such as oleic, linolenic, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and conjugated linoleic acid (CLA). Previous studies have suggested a contribution of ω-3 polyunsaturated fatty acids (PUFAs) to reduce pro-inflammatory markers and, have shown they have antimicrobial and negative properties in relation to biofilm formation. These types of biofilm structures are characteristic of proximal CRC. For these reason, ω-3 PUFAs it is thought that they could modify the altered intestinal microbiota in patients at high risk of CRC towards a less pathogenic environment, correcting the gut dysbiosis. Moreover, they have higher selenium levels (Se), an element with essential biological functions which has been suggested improving effects in combination with other anticancer agents in CRC and taking part in the modulation of several processes, such as the immune response, apoptotic cell death, DNA repair, response to oxidative stress, carcinogenic metabolism, tumorigenesis and angiogenesis. Finally, they contain type A2 beta casein, which differs from A1 beta casein by a single amino acid at position 67 of a 107 amino acid chain. This fact is very important because beta casein contains a chain of amino acids called "beta casomorphin" (BCM7) with negative health effects reported. The proline 67 in beta casein A2 has a strong bond with BCM7 that does not allow it to separate and flow freely in milk to be absorbed. However, the mild bond due to histidine 67 in beta casein A1 allows BCM7 to reach the intestinal wall and be absorbed, being associated with intestinal discomfort, gastrointestinal transit time and stool consistency disturbances, abdominal pain and, increased levels of some inflammatory markers.

For these reasons, in this proposal the investigators aim to determine whether the change from conventional dairy products to UNICLA-A2 products but maintaining the habitual consumption habits in "real life" conditions, without forcing or inducing greater consumption, will have positive effects on maintaining the intestinal integrity by reducing the inflammatory profile, and leading the gut microbiota to a less pathogenic environment in patients at high-risk of CRC development.

Inclusion Criteria:

1. Participants diagnosed with high-risk polyps in the colorectal cancer screening programme or in the relative's colon cancer prevention program or patients who are in follow-up due to prior detection of polyps with any of the following characteristics:

   • At least 10 adenomas
   • At least 5 proximal serrated polyps (PSP)
   • At least 2 serrated polyps with diameters ≥10 mm
   • Serrated Polyposis Syndrome (SPS)
   • Early invasive CRC (stage pT1) endoscopically resected (surgery not required)
   • A sessile or flat lesion ≥ 20 mm with fragmented resection
   • Patients with previous resection of polyps in which the resection margin was not assessable and are considered susceptible to repeat colonoscopy
   • Patients with intramucosal carcinoma in situ or invasion of the lamina propria (pTis)

2. Regular consumer of milk and dairy products.

3. Informed consent form signed.

Exclusion Criteria:

1. History of allergic reaction attributed to compounds of similar chemical composition to the study agents.
2. Incomplete colonoscopy or with poor quality criteria, Boston <6.
3. Concomitant acetylsalicylic acid (ASA), NSAIDs, misoprostol, corticosteroids or statins needed on a regular or predictable basis during the time of the study.
4. Previous gastrointestinal surgery (colon or small intestine or gastric) that affects the absorption of nutrients.
5. History of familial adenomatous polyposis.