Does your latte really send you to the ladies' room? For most people, the caffeine in coffee is simply a mild diuretic, which makes the body excrete more liquid. (Think: Pee more often.) But some people are especially sensitive, so they'll experience more of a laxative effect. Why? Caffeine stimulates the colonic muscles, which causes bowel movement contractions that are very similar to the ones from eating a meal.
But although coffee can loosen your stools, other add-ins may be to blame: dairy, excess sugar, and sorbitol (an artificial sweetener used as a laxative) can also cause diarrhea.
"Some people don't realize that they're actually lactose intolerant if they've been adding milk to their coffee and assume that it's the coffee giving them tummy troubles," explains Good Housekeeping Institute nutritionist Jaclyn London. "So if it's upsetting your stomach, you might want to try a non-dairy version for awhile!"
Your stomach may also be feeling weird because the acids in coffee also increase the production of bile: Coffee makes the gall bladder release it into the intestines. But don't worry, drinking caffeine isn't linked to causing (or necessarily worsening) conditions like irritable bowel syndrome. In fact, it's even been shown to decrease your risk of colorectal cancer. Seriously, coffee's health benefits are endlesss!
But since we drink this stimulant first thing in the day (or when we need a boost) it wakes up the system in more ways than one, says London. "So I'd say limit yourself to about two or three cups (400 mg) so you get all the health benefits — without a guaranteed race to the restroom."
