CYP7A1 and fatty liver disease: The increased risk of fatty liver disease might be caused by TMAO due to its effect on decreasing the total bile acid pool size16 via the following mechanisms: 1) by decreasing the synthesis of bile acids due to the inhibition of the key enzymes CYP7A1 and CYP27A116; and 2) by limiting the enterohepatic circulation of bile acids between the liver and intestines due to the repression of organic anion transporter (oapt) and multidrug resistance protein (MRP) family protein expression16.