Conjugated linoleic acid (CLA) purportedly alters body composition, glucose tolerance, hepatic function, lipoprotein distributions, and other markers of health. Results are often inconclusive or contradictory, and presently, no studies have investigated the effects of naturally incorporated CLA from pasture-fed beef and dairy products on human health. We hypothesized that a diet comprised of foods naturally enriched with CLA from pasture-fed cattle would result in improved insulin sensitivity, body composition, circulating lipids, and other disease risk factors when compared to a diet comprised of commercial foods naturally low in CLA from grain-fed cattle. Eighteen healthy women 20 to 39 years of age consumed one of these 2 diets for 56 days. Balanced nutritionally complete diets comprised of 31% energy from lipid, 13% from protein, and 54% from carbohydrate were administered, with the primary difference being CLA content (CLA diet: 1.17 g/d; control diet: 0.35 g/d). The CLA diet did not result in any differences in insulin sensitivity, body composition, circulating blood lipids, or other measured disease risk factors as compared with the control diet. Thus, we conclude that a diet naturally enriched with over a 3-fold increase in CLA from pasture-fed cattle did not significantly alter selected health risk factors in healthy, premenopausal women as compared with a similar diet composed of foods from grain-fed cattle.
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