The bioavailability of ferulic acid is governed primarily by the food matrix rather than its metabolism in intestine and liver in rats

Abstract

The physiologic importance of ferulic acid (FA), and notably its antioxidant properties, depends upon its availability for absorption and subsequent interaction with target tissues. Because FA is widely present in cereals, the aim of the present study was to investigate its intestinal and hepatic metabolism in rats by in situ intestinal perfusion model (from 10 to 50 nmol/min), and its bioavailability in supplemented diets (from 10 to 250 μmol/d) or in a complex cereal matrix, i,e., whole flours from Valoris (Triticum aestivum) or Duriac (T. durum) cultivars and bran or white flour from the Valoris cultivar. In perfused rat intestine, net FA absorption was proportional to the perfused dose (R2 = 0.997); once absorbed, FA was completely recovered as conjugated forms in plasma and bile secretion (representing 5-7% of the perfused dose). In rats fed FA-enriched semipurified diets, FA absorption was quite efficient because ∼50% of the ingested dose was recovered in urine. This extensive elimination by kidneys limited FA accumulation in plasma (typically 1 μmol/L in rats fed 50 μmol FA/d). In contrast, in rats fed cereal diets providing 56-81 μmol FA/d, urine excretion was 90-95% lower than in rats fed FA-enriched semipurified diets, and plasma concentrations were ∼0.2-0.3 μmol/L. Thus, the cereal matrix appears to severely limit FA bioavailability. This inherently low bioavailability of FA in cereals likely reflects FA association with the fiber fraction through cross-linking with arabinoxylans and lignins.