Could a fecal transplant help to re-establish DAO?

In her ongoing Q&A on histamine intolerance, Dr Janice Joneja was asked whether a fecal transplant might help to re-establish viable levels of DAO (diamine oxidase), the enzyme which helps to metablise histamine.


I have normal serum levels of histamine and extremely low levels of DAO. Lots of people from Dad's side of the family have a lot of these symptoms so I suspect a genetic pathway. Has anyone tried fecal transplant to get the DAO re-seeded & working right?

Dr Joneja says:

I will try to answer this in very general terms as you do not provide me with much information about yourself.  When you say...”a lot of these symptoms”, I am assuming that you mean symptoms of histamine intolerance?  Furthermore if you have normal levels of histamine I would expect that you do not have any symptoms of histamine excess.  And since there are no reliable tests for diamine oxidase (DAO) levels in the body I would question the validity and relevance of the tests in your case. 

Nevertheless I am taking this opportunity to discuss the points you have raised within the context of evidence-based medicine.

Faecal microbial transplantation (FMT) in which faeces from a donor are transplanted into a recipient via a nasojejunal tube (through the nose to the lower part of the small intestine) or colonoscope (via the rectum in to the colon) has been used in the last few years in treatment of a variety of intestinal complaints that have resisted more traditional methods of management.  These conditions include overgrowth of Clostridium difficile, especially in the elderly, inflammatory bowel disease and irritable bowel syndrome.  For readers who like more scientific information, a recent paper provides a nice review of the topic .  The aim of the treatment is to establish a more “healthy” microflora in the lower bowel of the patient and to displace microorganisms that may be contributing to the disease. This is a relatively new field and a great deal of research remains to be carried out to ensure the safety and efficacy of the practice in the treatment of various conditions.

Manipulation of the microflora of the digestive tract is not a new concept.  Since the early 1990s foods containing probiotic cultures have become established as a method of introducing new strains of microorganisms into the body in the management of an ever-increasing number of conditions.  As in faecal transplantation, the aim is to displace unwanted organisms by introducing beneficial strains together with a source of nutrients to aid in their establishment in the new environment. 

You have suggested the idea that transplantation of microorganisms might aid in increasing diamine oxidase (DAO) in the digestive tract.  However, at this time we have insufficient research to enable us to actually do this.  As you will learn from my various publications, we do know that certain bacteria can synthesise (manufacture) diamine oxidase.  Unfortunately we do not have any research that has definitively identified these strains, nor established their safety within the body. Furthermore, microorganisms capable of converting histidine from residual proteins in the digestive tract into histamine occur naturally as part of the normal microflora of many people.  When these organisms are present in large numbers it is probable that this is a cause of histamine excess or sensitivity.  Clearly, if we could displace these microorganisms with those capable of producing DAO it would be of great benefit to the histamine sensitive individual.  However, as must now become clear, if we attempt faecal transplantation in an attempt to introduce DAO-producing strains into the histamine intolerant individual, we could more than likely introduce bacteria capable of producing histidine decarboxylase, and thereby actually increase the level of histamine entering the patient’s circulation.  Until we have much more information on the strains capable of producing DAO and how to introduce them safely, I would definitely not attempt FMT as a method to manage histamine sensitivity.

Malnick S, Melzer E. Human microbiome: From the bathroom to the bedside.  World Journal of Gastrointestinal Pathophysiology Aug 2015;6(3):79-85 

NB Provided that the issue is an excess of histamine rather than an allergy to it, DAO supplements may also be helpful. You can buy them under the trade names DAOSiN and Histame in the UK and Swanson's DAOSiN in the US.

NB Information on this site is not a substitute for medical advice and no liability can be assumed for its use.

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