Also known as maltitol syrup and hydrogenated glucose syrup, HSH can be a strong cause of stomach problems. Can Whey Protein Powder cause diarrhea? I find any pre packed protein supps (bars, shakes) will hit me a lot harder, so I buy wpi and just mix it myself with water, that way I can control how much protein I am having. However, you may suffer from diarrhea with high intakes of protein, depending on your food choices. Depending on the type of HSH, the maltitol and sorbitol content can vary, and the sweetness of HSH swings from 25% to 50% of sucrose. Too much protein in anything will give you diarrhea. Xylitol This is not uncommon, as over 60% of the population have some level of lactose intolerance. Most protein bars are made from milk or soy proteins, which can cause stomach aches if you have an allergy or intolerance towards these proteins. Yes, diarrhea is a common symptom from whey protein powder that can be experienced by those that suffer from lactose intolerance. Stop eating protein bars if you experience stomach aches every time you eat them. HSH sweeteners are used in a wide variety of candies, gums, mints, and protein bars. Protein is an important nutrient that provides building blocks for the tissues in your body.