September 18, 2018

Fecal Transplants: Is sterile saline necessary for FMT?


I read through your fecal transplant guidebook, today was my first day and all seemed ok (I’ve been through worse ha).  One question though … I mixed 2 cups water with 1 tsp salt to make the saline … does this calculation seem correct to you?  And why do we need the salt?  I actually never even expelled what I put in me and it’s been oh about 4 hours.  Does the salt in the water make you absorb all the water?  Thanks Michael.

– J

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Hi there,

Congratulations on taking the plunge! In answer to your questions, the mixture for sterile saline is 0.9% saline or 9 grams per liter.  So your mixture calculations are just about right. 2 cups of water is about 473 MilliLiters and 1 tsp of salt is about 5 grams, .

Is the salt necessary? The short answer is probably not, and I have heard of others who have done this without it negatively impacting their results. However there are some things to consider, to where it might still be worth doing.

I used the saline mixture myself and advise it’s use in my fecal transplant guide because that’s what the doctors’ had in their instructions. But why did the doctors so that?  Sterile saline is used for IVs, contact lens solution and to clean wounds among other things because it is supposed to more closely match bodily fluids. Since doctors use sterile saline for IVs, wound cleaning and other things, that is their go to solution of choice.

It terms of how it could help in this case where it is going into the intestines, the salt could make the mixture more closely match the bodily fluids and deliver
salts to the body that are otherwise lost through watery stool. Plain water without saline could also dilute the existing sodium concentrations in the body, however so does drinking plain water. With adequate daily salt intake this should not cause any significant problems. However if you are losing lots of fluids from intense exercise or diarrhea, sports drinks with sodium and other salts (electrolytes) in them can be helpful.

What would help in retaining the enema for longer or even completely absorbing it is by slowing down bowel muscle movements to give the
intestines time to soak up water. That’s how drugs that are used to treat diarrhea work. Another contributing factor would be the use of a lower volume of water which would also help since there would be less water to have to absorb. That is why I used about 8 oz. (1 cup / 236 mL) from a rectal syringe and advise that in my fecal transplant guide book as well.

So reduced water volume and reduced bowel muscle movements are the main reasons why you were able to
just absorb the enema contents like that. My bottom line opinion is the saline can’t hurt but is probably unnecessary.

What is more important is that the water should be clean and free of chemicals and / or pathogens.  I believe store bought distilled water from a trusted source should be safe enough for this. Remember this water is being mixed with fecal matter and is then going into the body’s equivalent of a sewage system. So some tips to help retain the enema longer or completely absorb it, are to keep the water volume closer to 8 oz. and slow bowel muscle movements through diet and / or medications. This makes the process of fecal transplants less of an inconvenience and might help the new bacteria become established more quickly too.

Good luck and keep in touch!