The Scientist: Dr. Roshini Raj, board certified gastroenterologist and internist, and founder of TULA probiotic skincare

The Answer: Maybe it has happened to you: over time, you notice that after you drink a glass of milk or eat a bowl of ice cream, you’re running to the bathroom the rest of the day. Could you suddenly be lactose intolerant as an adult? It’s possible.

Most people experience a gradual decline of lactase (the enzyme that helps your body digest milk products) activity as they age. Lactase is produced by the cells lining your small intestine, and if they don’t produce enough, the lactose you consume passes undigested into the large intestine. There, it interacts with bacteria and causes all those nasty stomach problems — diarrhea, gas, bloating — that those with lactose intolerance know all too well.Lactose intolerance could be caused by anything that disrupts the functioning of the small intestine — for example, surgery, an illness such as Crohn’s disease or even food poisoning. Sometimes the intolerance is temporary and resolves itself; other times, it’s permanent. For some, the natural lactase decline happens quicker and more drastically, causing intolerance that was never there before.

If dairy isn’t sitting as well with you as it used to, try this self-test: stop consuming dairy products for five days, and on the sixth day, drink a glass of milk. If your symptoms resolve during the dairy-free days and come back when you reintroduce it, you most likely have developed lactose intolerance. Your doctor can perform some tests to determine if you truly have the condition, and help you find the right medication if you simply can’t imagine a life without dairy. Many lactase enzyme supplements, such as Lactaid, are even available over the counter.