Many people commonly consume fiber-enriched foods to promote weight loss and prevent chronic diseases such as diabetes and cancer. However, in some individuals—particularly those with a silent vascular deformity—consumption of highly refined fiber may increase the risk of liver cancer, new research has found. While inulin promotes metabolic health in most who consume it, Vijay-Kumar and colleagues discovered that about one in 10 standard, seemingly healthy lab mice developed liver cancer following consumption of the inulin-containing diet caused by a previously unnoticed congenital defect called a portosystemic shunt. Normally, blood leaving the intestines goes into the liver where it is...