Table 1.

Examples of how different steroids interact with gut microbiota

Steroids	Modulation of Steroids by Gut Microbiota	Effect of Steroids on Gut Microbiota
Sex hormones	Deconjugation by enzymes including sulfatase and glucuronidases Biotransformation of unconjugated hormones	Enhances intestinal alkaline phosphatase (IAP) activity Facilitates intraluminal transport of sIgA which neutralizes pathogenic bacteria Regulates plasma immunoglobulin levels and B cell function
Corticosteroids	Regulate intestinal corticosteroid production in response to stress Biotransform into 21-dehydroxylated products or androgens Influence GR activity	Mediate the effects of stress through modulation of the microbiome Modulate the oral microbiome in a metatranscriptomic study Modulate infant intestinal microbiota composition with altered maternal cortisol level
Bile acids	Deconjugates by bile salt hydrolase (BSH) Conversion of primary into secondary bile acids by 7-dehydroxylation, 12α-dehydrogenation and desulfation	Exhibit antimicrobial and cytotoxic properties by inducing membrane damage or through FXR Regulate gut microbiota composition through FXR
Vitamin D3	Increase 25-hydroxyvitamin D and biosynthesis of 7-dehydrocholesterol by probiotics and prebiotics, respectively Upregulates VDR expression by probiotics Hydroxylate and activate vitamin D3 by cytochrome enzymes	Increase gut microbial diversity and Akkermansia abundance Elevate tight junction protein expression and improves intestinal barrier function Enhance the production of antimicrobial peptides

FXR, farnesoid X receptor; VDR, vitamin D receptor.