Dear Dr. Roach: In a recent column that touched on taking laxatives daily, you mentioned a sugar called lactulose that you recommend for constipation. I’m wondering if other sugars have the same effect. My 70-year-old wife drinks several cans daily of diet lemon-lime soda that contains sucralose. She also tends to have fairly loose, even runny bowel movements. Could the amount of sucralose that she’s ingesting be responsible for this?
T.T.
Your logic is completely sound. Lactulose is a synthetic sugar that was designed to be nonabsorbable. It stays in the bowel and brings water along with it, making it a useful treatment for constipation. It’s also used to treat people with bad liver disease such as cirrhosis by helping trap ammonia in the gut, since a damaged liver can’t metabolize ammonia. This helps treat and prevent a condition called hepatic encephalopathy. Of course, the major side effect will be loose bowel movements (sometimes diarrhea).
Sucralose is a synthetic sweetener that also isn’t well-absorbed. Like lactulose, it mostly remains in the gut. (Only 15% is absorbed and metabolized.) It is very sweet, 500 or so times sweeter than sugar, so very little is needed. The effect of trapping water inside the gut isn’t as prominent as with lactulose; however, it is absolutely true that some people will be very sensitive and develop diarrhea. This is not only due to it trapping water, but also due to changes in the types of bacteria in the intestines (called the microbiome).
Decreasing the amount she drinks would be a useful diagnostic test. If her symptoms get better immediately, it’s likely the water-trapping effect. If it gets better after a few days to a few weeks, it’s likely the microbiome effect. If it doesn’t get better at all, then it probably wasn’t due to sucralose.
Other compounds used as sweeteners, especially sugar alcohols like sorbitol, xylitol, maltitol and erythritol, can cause similar symptoms in some people.
Dear Dr. Roach: I am a 59-year-old woman who takes 20 mg of atorvastatin for high cholesterol. During the summer, my lab work showed an elevated AST level of 49 U/L and an ALT level of 42 U/L, which I found out are related to liver function. My doctor asked that I repeat the lab work three months later. This time, the AST was normal, but the ALT was still elevated a bit at 35 U/L. My doctor has left the practice, and no one has called to follow up. Is this something I should be worried about?
K.R.
AST and ALT are enzymes made by the liver that are released in small amounts into the blood, but they can also represent damage to liver cells when the levels are high. Atorvastatin is metabolized by the liver, and about 2% of people will have slightly high levels while taking atorvastatin.
Only about 0.7% of people will have levels that are three times the norm (a level over 105 U/L). Even so, when it comes to people who have stable levels without symptoms, I generally do not stop or adjust the dose of atorvastatin. The benefit to preventing a heart attack is worth having slightly high liver-enzyme levels, which almost never indicate a serious problem.
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 [email protected]
