DEAR DR. ROACH: I am in my early 90s and have read your column and those before yours, and have not seen this topic covered.
Long ago, my primary doctor told me that many people suffering from constipation are not aware that they are ignoring the natural urge for a bowel movement that comes within 15 to 30 minutes after every meal, often because it’s not convenient or they are rushing off to work, school, etc. He said that his wife had this problem, being a schoolteacher and having to return to the classroom soon after lunch. It was the same for the students. He said that when the urge is ignored, the stool retreats in the colon, and gets firmer each time as more moisture is drawn out. In older people it can be less intense and not noticeable. For this reason, I have never gone on a bus tour, assuming after stopping for a meal, that the driver is not going to wait for all of the passengers to “go.” Now in these days when many of us try to increase and balance the amount of fiber we eat, to make the stool more predictable, I can schedule my appointments accordingly–and that works well for me. Yes, after every meal. — M.H.
ANSWER: Not everybody will have the urge to have a bowel movement after every meal. Over 95% of healthy people report a bowel movement between three times daily and three times weekly. It’s helpful to know one’s own pattern in order to identify a potential problem, but also for the reason you identify: If you ignore the sensation of needing to defecate, it can lead to difficulty passing a bowel movement later on.
It’s unfortunate that you have had to limit your social choices around your bowel movements. People who have functional bowel issues that change bowel frequency (I especially mean irritable bowel syndrome) often need to change their social lives around the demands of their colon. It sounds as though you have had to make some sacrifices as well. Still, if you really want to go on a tour, you might still try.
DEAR DR. ROACH: You recently wrote that sodium intake increases kidney stone risk. I thought kidneys filtered out serum calcium, meaning calcium intake causes calcium oxalate stones. As someone who suffered from hyperparathyroidism and kidney stones, it is my understanding that excess serum calcium causes stones. Nowhere in my research into this disease, nor in discussions with my parathyroid expert surgeon, did I ever hear of salt contributing to stone formation. I would greatly appreciate a clarification as to salt’s role in the formation of calcium stones, as I do love my salt. — A.G.
ANSWER: I am always happy to discuss physiology.
A high sodium diet requires the kidney to excrete the excess sodium. The sodium transporters across the membrane in the kidney require calcium to be excreted as well. A high sodium diet increases calcium loss in the urine by six-fold in laboratory studies. The high amount of resultant calcium in the urine will lead to stone formation in people genetically predisposed to do so.
Even in people who do not form stones, a high sodium diet will cause the body to excrete excess calcium, potentially leading to osteoporosis. Even though blood pressure is the major argument against a high sodium diet, kidney stones and bone health are other reasons not to take in excessive sodium.
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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 ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.
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