Indole is an important biomarker in biological and clinical specimens. It can be detected in human breath, feces, saliva and urine. The normal smell of human feces is largely due to this compound.
Indole is an example of a microbe-generated signal substance that has positive effects on our health and the health of the microbiome. Normal-smelling feces may be an underestimated health indicator.
In the liver indole is sulfonated to indican (3-indolesulfonic acid) and its levels could be also indirectly measured by indicans test. See MeBO-Biolab studies (NCT02692495) for more.