This involves taking stool specimens from healthy individuals and transplanting it into the gut of people who suffer with bowel problems that relate to faulty or pathogenic organisms in the gut. This may be a factor in certain chronic conditions that are difficult to treat with conventional medication and antibiotics. These include Inflammatory Bowel Disease (Crohns and Ulcerative Colitis), Irritable bowel syndrome and Clostridium Difficile infections, as well as non-specific colitis and chronic constipation. It has also been shown to have a beneficial effect on conditions such as Parkinson’s Disease, Diabetes and even obesity by altering bowel flora. There doesn’t seem to be any application to use this treatment for food allergies to foods and other allergic conditions. The healthy persons faecal material is transplanted by enema, oro-gastric tube via the mouth or swallowing freeze dried faecal capsules.

Reference: https://en.wikipedia.org/wiki/Fecal_microbiota_transplant