It’s unclear, though there are other good reasons for limiting your intake of the sweetener. Animal studies have found that consuming a lot of high-fructose corn syrup can damage the liver and contribute to nonalcoholic fatty liver disease. Whether fructose causes liver problems in humans hasn’t been well studied. But high intakes may indirectly harm the liver by increasing the risk of obesity, diabetes, and elevated blood levels of triglyceride fat, all of which in turn increase the risk of liver disease. A far clearer reason to limit your intake of high-fructose corn syrup is that it’s high in calories, has no nutritional value, and usually shows up in foods that aren’t that healthy to begin with—namely soda, fruit drinks, and processed sweets. And too much fructose, as with sorbitol, lactose, and raffinose sugars, can cause upset stomach, gas, or diarrhea.