Researchers at the Auckland Liggins Institute say the faecal material or stools of some people are better than others when it comes to treating some intestinal problems.
They say these people are "super donors", but that more needs to be known before faecal transplants could be used more widely, for problems including Alzheimer's Disease and cancer.
The researchers have just had a review article published in the journal Frontiers in Cellular and Infection Microbiology.
They say "poop transplants" have become routine treatment for nasty, recurrent diarrhoea infections, such as C-difficile, but that trials for other conditions "have hit a bum note".
Now they say a review of the evidence shows that time and again, there was one donor whose stool was substantially more likely to lead to clinical improvement than others in the same trial.
These "super donors" could provide the necessary bacterial to restore gut chemicals that are lacking in illnesses like Inflammatory Bowel Disease (BID), and diabetes.
The researchers add: "With Alzheimer's, multiple sclerosis, cancers, asthma, allergies and heart disease all associated with changes to gut bacteria as well, understanding what makes a faecal super donor could poop the new panacea."
Senior author Justin O'Sullivan said the past two decades had seen a growing list of medical conditions associated with changes in the microbiome - bacteria, viruses and fungi, especially in the gut.
"In fact, we already know that changes to the gut microbiome can contribute to disease, bases on studies in germ-free mice as well as clinical improvement in human patients following restoration of the gut microbiome by transplanting poos from a healthy donor.
"While the overall cure rate for recurrent diarrhoea infection exceeds 90 percent, trials of faecal transplantation to reduce symptoms in other conditions like inflammatory bowel disease exacerbations and type 2 diabetes have had much more mixed results, averaging nearer 20 percent."
He added: "The patters of success in these trials demonstrates the existence of 'super donors', whose stool is particularly likely to influence the host gut and to lead to clinical improvement."
Dr O'Sullivan said transplants from super donors achieved clinical remission rates of perhaps double the average.
"Our hope is that if we can discover how this happens, then we can improve the success of faecal transplantation and even trial it for new microbiome-associated conditions like Alzheimer's, multiple sclerosis and asthma."
He said super donors' stools tended to have high levels of specific "keystone species".
These were bacteria that produced chemicals whose lack in the host gut contributed to disease.
"In inflammatory bowel disease and diabetes for example, keystone species that are associated with prolonged clinical remission produce butyrate -- a chemical with specialised functions in regulating the immune system and energy metabolism."
But Dr O'Sullivan said there was clearly more to super donors than keystone species.
"The balance of other bacteria present, and the interactions between them, seems to influence the retention of keystone species," he said.
There was more to it, and researchers recommend that future faecal transplant trials routinely record information on the genetic background and dietary intake of recipients "so that we can better understand their impact on transplant engagement and clinical remission".