Phenylacetic oil: a possible simple test for fat absorption.

The preparation of a phenyl[1-14C]acetic acid oil is described. The absorption pattern of the phenylacetate in this oil is similar to that of oleic acid in triolein when examined in rats under conditions that may interfere with digestion and/or absorption. The safety of this compound, which is a normal metabolite, was established by the absence of the 14C label in various tissues five days after its administration to rats. When tested in 18 normal human volunteers 66.6 +/- 16.0 (S.D.) percent of the phenylacetate was recovered in a five hour urine collection. In two patients with malabsorption, less than 30% of the label was recovered in the urine over the same period. The half-life of the phenylacetate was determined to be 1-1.5 h. Our preliminary results indicate that phenylacetic oil may serve as a useful simple clinical test for fat absorption.