NAT1 and colorectal carcinoma: Whereas one small study found interaction between the number of servings per day and NAT2 acetylator status (Chan et al. 2005), no association was found between the amount of total or processed meat intake or number of servings and NAT1 or NAT2 status in relation to the risk of CRC in three other studies (Chen et al. 1998; Sorensen et al. 2008; Nothlings et al. 2009).