Aspartame can harm the gut and negatively impact gluten tolerance and metabolism. It has been shown to cause cancer in studies done on mice and linked to risk of lymphoma and leukemia in men and women. The WHO has classified aspartame as a potentially carcinogen, and said that it may cause liver cancer. Consumption is also linked to increased risk of heart disease. Aspartame has carcinogenic potential, may alter cell viability, alter brain antioxidant status, and can promote hyperglycemia. It has been shown to cause headaches in some people.