In vitro study of the bioavailability of fatty acids in cow milk containing conjugated linoleic acids produced in vivo or added in synthetic form

The intestinal absorption of fatty acids from milk, especially conjugated linoleic acids (CLA), was evaluated using an in vitro simulator. Milk was enriched with c9,t11 CLA by feeding a cow a diet containing 4% safflower oil or by emulsifying synthetic CLA in the form of free fatty acid or triacylglycerol, then standardized to 1.0% or 3.25% fat. Fatty acid bioavailability depended on chain length, presence of double bonds, and the percentage of fat. Absorption was more efficient in the presence of 1.0% fat. The bioavailability of c9,t11 CLA at 3.25% fat was 89% in the milk from the cow fed the safflower-oil diet, and 85% and 71% in milk enriched with synthetic free CLA and synthetic CLA in the form of triacylglycerol, respectively. At 1.0% fat, these values were 90%, 99% and 96%, respectively, suggesting that bioavailability of CLA in milk is affected by the percentage of fat present.