Ginger and Gut Microbiome (GINGER)

This is a pilot trial to evaluate the feasibility of conducting a large randomized trial and estimate the effects of ginger extract on the gut microbiome. The pilot study will recruit from multiple sites 95-100 subjects aged 50-75 years old who were diagnosed with colorectal adenoma within the last five years. There will be 47-50 subjects in the treatment group and 47-50 in the placebo group. The subjects will be randomized to receive either 2000 mg of ginger extract per day (1000 mg twice a day) or matching placebo. Subjects will provide three stool specimens for analysis of the intestinal microbiome over a 12-week period at the following intervals: Week 0 (Day 1), Week 6, and Week 12. Although the gut microbiome is stable within a period of 1-2 months, a control arm will be included to account for potential dietary and other changes that may affect the gut microbiome. Gut microbiome composition - the presence, abundance, and diversity of bacterial taxa - will be derived by sequencing microbial 16S ribosomal RNA genes. Primary Aims: Aim 1 is to estimate the impact of a 6-week daily intake of 2000 mg of ginger extract on the composition of the gut microbiome using a randomized placebo-controlled double-blinded design, i.e. examine the change of microbiome over time within and between the subjects. Aim 2 will examine the correlation between the ginger-related changes in microbiome profile with the levels of circulating biomarkers: urinary Prostaglandin E (PGE) metabolites. Hypothesis: In the ginger versus placebo arm, gut microbiome will shift towards a lower proportion of pro-inflammatory, bacteria associated with colorectal cancer (CRC) and higher proportion of anti-inflammatory, CRC-protective bacteria. Secondary Aim: 1. At the end of the study, we expect to show that ginger decreases the relative abundance of pro-inflammatory, CRC-predisposing taxa and increases the abundance of anti-inflammatory, CRC-protective taxa, i.e., demonstrate that ginger boosts changes in gut microbiome that are protective against CRC, as well as assess ginger-induced changes in immune response. 2. The similarities of bacterial profiles will be compared between three time points baseline and 6 Weeks and 12 Weeks to estimate whether 6-week is a sufficient time for washout.