Though the association between the salivary microbiome is similar to that of the oral microbiome, there also exists an association the salivary microbiome and the gut microbiome. Saliva sampling may be a non-invasive way to detect changes in the gut microbiome and changes in systemic disease. The association between the salivary microbiome those with Polycistic Ovarian Syndrome has been characterized: "saliva microbiome profiles correlate with those in the stool, despite the fact that the bacterial communities in the two locations differ greatly.