Conjugated Linoleic Acid and Dietary Beef

Introduction Conjugated linoleic acid (CLA), a naturally occurring trans fat, is commonly found in ruminant animal sources such as beef, lamb, and dairy products (e.g., milk and cheese). Over the past two decades a wealth of research, mainly from in vitro and experimental animal studies and limited human investigations, has examined potential health benefits of CLA. This research on the biological functions and health benefits of CLA dates back to the 1980s when scientists at the University of Wisconsin observed that an anti-carcinogenic compound (later identified as CLA) isolated from grilled ground beef inhibited chemically induced skin cancer in mice (1). Since then, numerous studies have investigated the effects of CLA on cancer, cardiovascular disease, body composition, and other conditions (e.g., insulin resistance, immune function, bone health). The physiological and health effects of CLA are reviewed in several recent publications (2-8). Also, a listing of the scientific literature on CLA since the 1980s can be found by logging onto www.wisc.edu/fri/clarefs.htm.