Tuesday, September 28, 2010

Chlorine makes life hard on gut bacteria

Hypothesis: Pool water kills intestinal bacteria.

I don't know if that hypothesis is true, but I make the following observations to support it:
  1. Beneficial bacteria normally live in the human gut (large intestine), and these aid in digestive processes.
  2. Chlorine is a chemical that is widely used to kill bacteria (though usually on the outside of the body).
  3. I swallow at least several mouthfulls of pool water every hour that I swim. I don't mean to, but it happens.
  4. I am gassy on days when I swim, generally in the evening and the following morning after a noontime swim.
  5. I am less gassy on days when I don't swim.
  6. Consuming yogurt within a few hours after a swim tends to reduce my bouts of intestinal gas.
  7. Yogurt is well known for containing bacteria that can aid in digestion.

All this makes sense to me, but there are problems with my observations:
  1. I know that gut bactreria aid in the uptake of certain vitamins (B vitamins?) into the intestinal wall and bloodstream. I am thankful for that. But I'm not sure whether there is a link between the absence of gut bacteria and the production of intestinal gas. 
  2. When I swallow pool water (inadvertantly), does the chlorine remain an effective antibacterial agent after it passes through the stomach and smal intestine?
  3. I am only one person. No hypothesis can be supported based purely on the findings of a single research subject. Therefore, if other swimmers are out there, please let me know I'm not the only one who gets gas after swimming.


  1. Hi - I read this with interest, as I am looking into info on the same. I have established (via DNA stool test, Metametrix) that I have low level of good bacteria. I swim in a chlorinated pool 3x per week. I might have had a low level of good bacteria without the swimming too - I had an undiagnosed gluten issue for a long time. Probiotics has not helped. Have you come any further in your research on chlorine and gut health? Many thanks.

  2. Dear ET, thanks for your comment. My swimming has continued but the intestinal gas seems to be less of a problem. I still get it sometimes, but the correlation with swimming seems to be less significant for me now. Maybe as my swimming technique has improved I am swallowing less water. Or maybe something else has caused my gas. For instance, I used to take a whey protein supplement on a daily basis. But I stopped doing that a few months ago. My gas issue might have been with the excess protein rather than pool water. Sorry I can't help you with any other research. Good luck!