Abstract
Glucosamine and chondroitin (G&C), typically taken for joint pain, are among the most frequently used specialty supplements by US adults. More recently, G&C have been associated with lower incidence of colorectal cancer in human observational studies and reduced severity of experimentally-induced ulcerative colitis in rodents. However, little is known about their effects on colon-related physiology. G&C are poorly absorbed and therefore metabolized by gut microbiota. G&C have been associated with changes in microbial structure, which may alter host response. We conducted a randomized, double-blind, placebo-controlled crossover trial in ten healthy adults to evaluate the effects of a common dose of G&C compared to placebo for 14 days on gut microbial community structure, measured by 16S rRNA gene sequencing. Linear mixed models were used to evaluate the effect of G&C compared to placebo on fecal microbial alpha and beta diversity, seven phyla, and 137 genera. Nine genera were significantly different between interventions (False Discovery Rate < 0.05). Abundances of four Lachnospiraceae genera, two Prevotellaceae genera, and Desulfovibrio were increased after G&C compared to placebo, while Bifidobacterium and a member of the Christensenellaceae family were decreased. Our results suggest that G&C affect the composition of the gut microbiome which may have implications for therapeutic efficacy.
Highlights
Glucosamine and chondroitin (G&C) are among the most frequently used specialty supplements by US adults [1]
Mean alpha diversity measurements did not differ between the treatments (6.45 ± 0.31 and 6.39 ± 0.32 for G&C and placebo, respectively); there was a significant difference in the overall microbiome community structure [p < 0.05, permutational multivariate analysis of variance (PERMANOVA)] after G&C compared to placebo
There were no significant differences between interventions in the seven phyla measured: Actinobacteria, Bacteroides, Cyanobacteria, Firmicutes, Proteobacteria, Tenericutes, and Verrucomicrobia [False Discovery Rate (FDR) > 0.05]
Summary
Glucosamine and chondroitin (G&C) are among the most frequently used specialty supplements by US adults [1]. Several large, prospective cohort studies have shown that use of G and/or C are associated with a reduction in colorectal cancer (CRC) risk [2,3,4,5]. Administration of G has been shown to improve inflammatory bowel disease in both animal models [6] and humans [7], and the combination of G&C reduced systemic inflammation in a small trial of healthy adults [8]. Beyond dampening inflammation, little is known about the potential effects of G&C on colon-related physiology in humans. G&C are poorly absorbed in the upper gut [9], and provide rich substrate for microbial metabolism in the colon. A few recent small-scale studies have evaluated G and/or C and the gut microbiome in humans and have reported changes in microbial abundances [9]. One study was conducted in vivo, and found decrea2soefd11trends in abundances of Staphylococcus, Enterococcus and Clostridium in OA patients after oral administration of
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