Abstract
Objectives
To identify the impact of cayenne pepper on the diversity of the gut microbiome and inflammatory biomarkers in the stool of adults with overweight or obesity.
Methods
31 individuals participated. All participants had a BMI > 25. Most participants were female (64.5%) and averaged 28 ± 8 years of age. Participants consumed two 250 mL servings of tomato juice or tomato juice plus 1.9 grams (0.8 g per dose) of cayenne pepper each day for one week before crossing over to the other study arm. The study design allowed participants to continue eating a mixed, complex diet but sources of capsaicin, the pungent component of cayenne, were to be avoided. Stool samples were collected in the home at the end of each treatment period. DNA was extracted from the stools, 16S rRNA libraries were made, and libraries were sequenced using an Illumina MiSeq. Sequences were processed using mothur, and data were analyzed in R using the vegan package.
Results
The spice intervention did not increase the richness of gut microbiota nor alter the overall gut microbiota composition at the genus level. However, at the single taxa at the genus level, participants who consumed tomato juice without cayenne had higher abundances of Prevotella and Bacteroides in their stool. Cayenne treatment did not affect either lipocalin or calprotectin levels in the stool. Calprotectin and lipocalin concentrations were positively correlated with each other, but only when participants were consuming cayenne pepper. Neither lipocalin nor calprotectin levels in stool of participants were related to gut microbiota richness or composition.
Conclusions
There was no detectable impact of the spice treatment on gut microbiota composition or intestinal inflammation in adults with overweight or obesity at the time of treatment. Though these results were unanticipated, given prior results in animal models, these results suggest that research in free-living humans must continue as treatments that are only effective under tightly controlled conditions will be of little use to most individuals.
Funding Sources
Academy of Nutrition and Dietetics Foundation/McCormick Science Institute as well as by startup funds provided by MSU and the MSU Department of Food Science and Human Nutrition.