Introduction
obesity, CRC, cancer, deaths, Colorectal cancer, weight loss, WL
OBESITY, CANCER, COLORECTAL CANCER, CARCINOGENESIS
Colorectal cancer (CRC) is the third most common cancer in the USA, with 151,030 new cases and 52,580 CRC-related deaths expected in 2022 [While there are several proposed mechanisms linking these modifiable risk factors with CRC, one potential mechanism is the bile acid (BA)-gut microbiome axis [The gut microbiota may also help explain how weight loss (WL), increased fiber, and decreased fat and animal protein consumption may decrease CRC risk in this subgroup. Aleman et al. demonstrated that a VLCD producing 10% WL reduced fecal BAs and DCA, and yielded a higher ratio of glycine-conjugated BAs, which correlated directly with gut microbial compositional changes [Based on these prior studies, we hypothesize that the largely plant-based and fiber-rich Mediterranean diet (MedDiet), which is associated with lower circulating DCA [To our knowledge, no studies have tested this hypothesis. To fill this gap, we will conduct a randomized controlled trial (RCT) enrolling AA/B, middle to older aged adults with obesity to examine the effects of a MedDiet alone (Med-A), WL through lifestyle intervention alone (WL-A), or a calorie-restricted MedDiet for WL (WL-Med) compared to typical diet controls (TDC), on BA metabolism, the gut microbiota, and intestinal epithelial markers associated with carcinogenesis.