Q: I am a very healthy 75-year-old woman. I have celiac disease and Sjogren’s syndrome but I cope with those very well. I’m active, a healthy weight, etc. My concern is that I fairly consistently have dark stools. I had a colonoscopy about a year and a half ago, had one or two polyps removed, was told I had diverticulitis (for which I have no symptoms). It is sometimes a challenge to get enough fiber in my diet since I must eat gluten-free and avoid all wheat, rye and barley. I do eat gluten-free oatmeal and cereal, a lot of salad, vegetables and some fruit; however, I do not always have a bowel movement every day. Sometimes I have a pain on my right lower side below my waist, mostly in the back, which goes away when I have a bowel movement.

I eat dark chocolate most days. Could this contribute to the dark color of my stool and should I be concerned?

A: For those readers that may not understand celiac disease and Sjogren’s, I will discuss them briefly. Celiac disease is the result of an immune reaction to eating gluten, a protein found in wheat, rye and barley. Celiac patients who eat gluten have an immune response of the small intestine. Over time, inflammation that damages the lining of the small intestine results in malabsorption that, in turn, causes weight loss, bloating and diarrhea. There is no cure for this disorder; however adherence to a strict gluten-free diet can promote intestinal healing and reduce or eliminate symptoms.

Sjogren’s is yet another disorder of the immune system that has two common symptoms – dry eyes and dry mouth. With Sjogren’s, moisture-secreting glands and mucous membranes of the eyes and mouth produce an inadequate amount of tears and saliva. Beyond this, some individuals may experience joint pain and stiffness, a chronic dry cough, extensive fatigue, skin rash and inflamed salivary glands. As such, additional areas of the body that can be affected include the kidneys, thyroid, liver, lungs, joints, and more. Treatment may include over-the-counter eye drops, prescription meds to increase the production of saliva, non-steroidal anti-inflammatory drugs (NSAIDS), and still more.

Dark stool could result from a number of causes, including things as simple as eating black licorice, taking iron pills, using Pepto-Bismol and other bismuth medicines, or eating blueberries. The foods you eat can cause your stool to appear tarry in color, so while I do not know how much dark chocolate you consume, dark foods can be to blame and may not necessarily indicate the existence of blood which is a concern; however, and on a more complex level, gastritis, a bleeding ulcer, bleeding in the upper portion of the digestive system, trauma, and widened veins in the esophagus – plus other possibilities – may be to blame.

You have already had a colonoscopy. Your physician may choose to order another because of the occurrence of your dark stool. He or she may order gastroscopy, where the doctor takes a look with a scope at your esophagus, stomach, and upper portion of the intestine, lab testing, barium studies, stool culture, testing for H. pylori, or angiography. I cannot tell you if you should be concerned because I do not know the cause. You should visit with your physician, present the history, have appropriate testing to rule out specific possible disorders, and allow your doctor to hone in on the cause. The simplest of tests is called a stool guiac in which a stool sample is tested for blood. Only then will you know if your dark chocolate may be to blame or if a bigger problem exists. Good luck.