Dear readers: You are sending me lots of great questions. But even though I write six columns a week, I can't answer them all.
Sometimes my answers prompt you to send additional questions -- and comments. Sometimes your comments take issue with something I've said. Periodically, I'll devote the column to the questions and comments you've sent me.
• Seeds, corn, nuts and diverticular disease: In a recent column I recommended a high-fiber diet for diverticular disease. Among the good sources of fiber I recommended were seeds, corn, nuts and popcorn. Several readers who have diverticular disease wrote me that their doctors had told them to avoid these foods.
Their doctors were taught the same thing I was: Seeds, corn, nuts and popcorn were bad for people with diverticular disease. In this disease, small balloon-like pouches push out from the wall of the large intestine. These little pouches can bleed or become infected, inflamed and painful. The theory behind the dietary advice was that a small and hard-to-digest piece of food -- like a kernel of corn, or a piece of a nut or popcorn -- could get stuck in the neck of the pouch. That, in turn, could cause the pouch to become infected and inflamed.
It was a reasonable theory, and in the absence of evidence against it, I thought it probably was true. Like your doctors, for many years I told my patients with diverticular disease to avoid these sources of fiber.
However, a major study based here at Harvard called the Health Professionals Follow-Up Study found no link between these foods in the diet and flare-ups of diverticular disease. If anything, people who ate seeds, nuts and popcorn had fewer flare-ups. Furthermore, two experts have stated in one of the major textbooks of medicine, called UpToDate, the following: "The authors have seen tens of thousands of diverticula and never seen a single seed (stuck in the neck of the pouch)."
So I no longer advise patients with diverticular disease to avoid these foods. They are all good sources of fiber. Several large studies indicate that people who have high-fiber diets for many years are less likely to develop diverticular disease.
• Urinary catheters and lubricant: In a recent column on urinary catheters, I explained that lubricant was used to ease the passage of the catheter up the urethra and into the bladder. The urethra is the natural tube through which bladder urine exits the body. What happens is that the lubricant is placed all around the front part of the catheter. When the catheter is pushed into the urethra, the lubricant enters the urethra and coats its walls. Several of you pointed out my reference to an "injection of lubricant into the urethra." Thanks for pointing out that my use of the word "injection" was imprecise.
• Dr. Komaroff is a physician and professor at Harvard Medical School. Submit questions or get additional information at AskDoctorK.com.