Effect of ginger supplementation on the fecal microbiome in subjects with prior colorectal adenoma

Abstract

Ginger has been associated with a decreased incidence of colorectal cancer (CRC) through reduction in inflammatory pathways and inhibition of tumor growth. Recent pre-clinical models have implicated changes in the gut microbiome as a possible mediator of the ginger effect on CRC. We hypothesized that, in adults previously diagnosed with a colorectal adenoma, ginger supplementation would alter the fecal microbiome in the direction consistent with its CRC-inhibitory effect. Sixty-eight adults were randomized to take either ginger or placebo daily for 6 weeks, with a 6-week washout and longitudinal stool collection throughout. We performed 16S rRNA sequencing and evaluated changes in overall microbial diversity and the relative abundances of pre-specified CRC-associated taxa using mixed-effects logistic regression. Ginger supplementation showed no significant effect on microbial community structure through alpha or beta diversity. Of 10 pre-specified CRC-associated taxa, there were significant decreases in the relative abundances of the genera Akkermansia (p < 0.001), Bacteroides (p = 0.018), and Ruminococcus (p = 0.013) after 6-week treatment with ginger compared to placebo. Ginger supplementation led to decreased abundances of Akkermansia and Bacteroides, which suggests that ginger may have an inhibitory effect on CRC-associated taxa. Overall, ginger supplementation appears to have a limited effect on gut microbiome in patients with colorectal adenomas.

Figure 1

Study flowchart. Subject population sizes and exclusion criteria for screening, enrollment, and study completion.

Figure 2

Diagram of interventions and sample collections. Overall study design for ginger treatment and subsequent stool and urine sample collections.

Figure 3

Microbiome structure in ginger supplementation. Alpha and beta Diversity analysis of microbiome composition between serial stool samples in subjects being treated with either ginger (orange) or placebo (grey).

Figure 4

Change in taxonomic mean relative abundance with ginger supplementation. Mean relative abundance and 95% confidence intervals of three CRC-associated taxa which demonstrated significant shifts between ginger (orange) and placebo (grey) during the 6-week intervention.