Sunday, December 5, 2010

Lactose and osmotic pressure

Since college, I have had some issues with lactose intolerance. My degree of tolerance has seemed to go up and down, which is puzzling and frustrating. After a recent bout, I decided to do some reading on the subject to try to gain more understanding of (and more control over) my situation.

I started with a Google search. After reading several webpages, the information was all starting to sound the same. Until I got to Wikipedia: "lactose... raises the osmotic pressure [in] the colon."

Osmotic pressure? I think I learned about that in ninth grade... I had to click through the wikilink to figure that one out. So, having something that cannot cross a semi-permeable barrier (gas and other by-products made by lactose-eating bacteria cannot cross the intestinal wall) causes water to cross the barrier (making watery, um, colon contents).

It looks like the unchangeable part of lactose intolerance is lactase deficiency: the inability to digest lactose in the small intestine. So the lactose travels down to the large intestine, where it is eaten by bacteria. At that point, the degree of symptoms (or even if there are any symptoms) depends on the behavior of said bacteria: how much gas and "increased osmotic pressure" they produce while eating lactose varies widely from bacteria species to bacteria species.

So I can eat cheesy pizza one week, and have polite bacteria that dispose of the lactose without causing me any trouble. The next week, not-so-polite bacteria cause me to seriously regret that cheesy lentil and leek loaf. How to encourage the polite bacteria to keep up residence? There seems to be a feeling that eating the same amount of lactose every day can help, but nobody really knows. So I haven't actually gained any more control from my reading.

But at least I can laugh while thinking about my situation as a problem with "osmotic pressure." Thanks, Wikipedia.

1 comment:

Roggey said...

This was interesting to read since my episodes with LI is about the same as yours. It *is* incredibly frustrating!