Health Advice



Drinking water is not the cause of diarrhea while traveling

By Keith Roach, M.D. on

DEAR DR. ROACH: While reading one of your recent columns, I learned that all water, except distilled, contains electrolytes. I wondered if there are differences in the amount of each electrolyte in drinking water in different places in Canada, and if so, whether that might explain why I experience cramping and diarrhea when I am visiting another place? Through experience, I have been able to avoid the problem by drinking only bottled mineral or distilled water when I am away from my home. In cases where I have been on lengthier holidays, after I lived through the initial distress, eventually, my gastric system calmed down and seemed to accommodate the new source of water. I felt that my malady might be some sort of domestic version of Montezuma's Revenge, but the analogy is inapt because the water I have consumed away from my home was not contaminated. -- M.T.

ANSWER: "Montezuma's Revenge" is an (insulting) term for traveler's diarrhea, specifically in reference to Mexico, where drinking water may be contaminated with bacteria, especially a type of E. coli that has a toxin. I don't think the answer to your diarrhea while traveling is in the water.

The quality of drinking water in nearly all of Canada and the United States is outstanding, and bacterial contamination is exceedingly rare, as you say. Similarly, electrolytes are kept at very low levels in most parts of North America, although some water softeners do put a fair bit of sodium into the water in exchange for other ions, such as magnesium and calcium. Still, none of these trace minerals are likely to cause diarrhea.

Some people develop diarrhea with stress. You don't have to be diagnosed with irritable bowel syndrome to have stress-related diarrhea, and travel is a stressful time for many. Other people are more likely to drink alcohol while traveling, and excess alcohol can cause diarrhea. I can't explain why drinking bottled or distilled water seems to prevent the problem.

DEAR DR. ROACH: I have been prediabetic for almost 20 years. Through diet and a prescription of metformin, I've been testing in the 115-120 range for several years. Recently, I started eating fresh pineapple. I noticed that if I ate a few small pieces in the evening, my morning glucose is in the 98-105 range. This morning, it was 95 -- a double-digit range I have not seen in years. How can there be warnings that pineapple raises blood sugar levels, but in my case, it's lowering my fasting glucose? -- K.G.

ANSWER: Fresh pineapple certainly has natural sugars, but it also has a lot of fiber, which slows absorption of sugar and minimizes the increase of blood sugar that consumption of any sugar can cause. Canned or dried pineapple usually has lots of added sugar along with the naturally occurring sugar, so avoid those. Increased fiber can help improve sugar levels. I don't know of anything else in pineapple that controls diabetes.

I wonder if you are eating pineapple instead of something else that might be raising your sugar more. One other thought: For many people with diabetes, a small snack before bed can keep the blood sugar from getting too low. If your blood sugar is too low at night, the body responds by releasing hormones that raise your blood sugar (called the Somogyi effect). It may be that a little snack is keeping that from happening.


Your new regimen is working. The key may be that you can have just a few small pieces. I wouldn't recommend more.


Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to or send mail to 628 Virginia Dr., Orlando, FL 32803.

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