Technical note: production of butter with enhanced conjugated linoleic acid for use in biomedical studies with animal models.

Cancer models utilize massive doses of carcinogen so that investigations of anticarcinogenic effects require equally large doses. Conjugated linoleic acids (CLA), predominately consumed in dairy products, are thought to be anticarcinogenic. Our objective was to naturally produce a CLA-enhanced butter for use in biomedical studies with animal models. To do this, we fed cows a low forage diet supplemented with sun-flower oil. This resulted in increases in content of CLA of milk fat, but the markedly elevated concentrations were transient and declined over a 3-wk period. By collecting milk fat over the first few days on the diet (d 7 to 10) and selecting cows with the greatest CLA concentrations, we were able to produce a butter in which CLA content was enhanced sevenfold over control butter (41 vs. 5 mg/g of fatty acids) and the cis-9, trans-11 isomer predominated (91%). Thus, butter produced by this method can be used to investigate the preventive role of CLA in natural foods with biomedical models of different types of cancer. Furthermore, the butter allows examination of the other beneficial health effects of CLA reported with animal models.