Chemotherapy and temporary lactose intolerance

Doctors and patients have often noticed that diarrhea is a very common side effect of chemotherapy for colorectal cancer. A new study by doctors and colleagues from Finland, explores a possible explanation for this trend: colorectal cancer chemotherapy may cause temporary lactose intolerance, resulting in symptoms like diarrhea and flatulence. This finding is significant because it will lead to greater understanding of the effects of the gastroenterological mucosal injury associated with chemotherapy and radiation. Hopefully, in understanding that diarrhea and flatulence are mere symptoms of temporary lactose intolerance, patients’ tolerance for the chemotherapy can be improved.

The article, "Lactose Intolerance Associated with Adjuvant 5-Fluorouracil-Based Chemotherapy for Colorectal Cancer," was recently published in Clinical Gastroenterology and Hepatology, the AGA’s clinical peer-reviewed journal. Results showed that the incidence of lactose intolerance among the tested population increased by 11 percent during the chemotherapy treatment for colon cancer. AGA member, professor of medicine at the Mayo Clinic College of Medicine and editor-in-chief of Clinical Gastroenterology and Hepatology, explains that adjuvant 5-fluorouracil-based chemotherapy is the type of chemotherapy commonly used for a number of malignancies of interest to gastroenterologists, most typically colon cancer. It differs from other types of chemotherapy because it might change the ability of cells in the small intestine to produce lactase, which is essential to break down lactose to two simple sugars. These breakdowns of lactose much occur for it to be absorbed into your system. If there is no breakdown, lactose draws water into the intestine and leads to diarrhea. That is why adjuvant 5—fluorouracil-based chemotherapy might lead to lactose intolerance while other types of chemotherapy do not.

As part of their study, researchers gave some patients twice-daily doses of lactobacillus rhamnosus to attempt to relieve the symptoms of diarrhea and flatulence associated with the temporary lactose intolerance. The patients’ symptoms were not relieved, but that may be because the dosage tested was too low. We point out that study need to be done with different doses of Lactobacillus rhamnosus because greater doses may indeed be more effective.

The good news is that the lactose intolerance associated with chemotherapy for colon cancer is very finite. It stops when the chemotherapy is completed. In addition, the symptoms of diarrhea and flatulence can be controlled with diet during the run of the treatment. It is possible to get tested for lactose intolerance when you are undergoing chemotherapy, and it is possible to experiment with higher doses. It should also be noted that some other types of good bacteria can help people process lactose – called "probiotics," dietary supplements like bifidus and acidophilus may be useful if you are suffering from temporary lactose intolerance, because they can produce the intestinal cell lactase. However, it may be best to simply discuss temporary dietary changes with your doctor if you are experiencing these side effects, and save your energy for emotional and physical stress associated with chemotherapy.