More research into the microbiome as a vector of treatment is being undertaken by mainstream medicine. The treatment of Clostridium difficile (C. difficile) infections was the more recent area of focus but now other areas are being considered.
This excellent research paper not only comments on the use of fecal microbiota transplants for metabolic syndrome, but it also provides a concise history fecal transplantation.
Fecal microbiota transplantation in metabolic syndrome: History, present and future: Full Article
As mentioned earlier, the most widely accepted explanation for the origin of metabolic syndrome is translocation of endotoxin (LPS) or direct translocation of gram-negative microbes, causing low grade inflammation. However, data on this phenomenon are still inconclusive.
Do see our forum thread about metabolic syndrome for more information on the subject.