Dr Kyle Staller is a gastroenterologist, so it may be surprising that many of his patients come to him complaining not only about stomach trouble but about their brains, too. Irritable bowel syndrome and other digestive dysfunction can be accompanied by a mental haze. People experiencing constipation and bloating, for example, may describe “a sense of heaviness or being weighed down both physically and mentally,” said Dr. Staller, who works at Massachusetts General Hospital in Boston. “So many of my patients talk about problems like fatigue, brain fog and feeling sluggish,” he added. Scientists are making progress in understanding how the pathway between the brain and the digestive system influences our overall health. They call it the gut-brain axis, and it has been shown to play a big role in immune system support, anxiety, depression, metabolism and disease prevention. It can also affect mental clarity. We asked scientists and clinicians what to know about the gut and brain fog.…