The distribution and relative hydrolysis of tocopheryl acetate in the different matrices coexisting in the lumen of the small intestine during digestion could explain its low bioavailability.

SCOPE

Vitamin E is present in feed and food mainly as d-α-tocopherol (d-α-TOL) but also as all-rac-α-tocopheryl acetate (rac-α-TAC) through supplementation. Its absorption efficiency is low compared to that of triacylglycerols. The aim of this work was thus to study the fate of TAC during digestion.

METHODS AND RESULTS

Using an in vitro digestion model, we showed that TAC was distributed between mixed micelles (36%), liposomes (9%), and nonsolubilized food debris (52%). A significant fraction of TAC was also found in emulsions when fat hydrolysis was not complete. Among the candidate esterases tested, i.e. cholesteryl ester hydrolase, pancreatic lipase, and pancreatic lipase-related protein 2, only cholesteryl ester hydrolase was able to hydrolyze TAC to all-rac-α-TOL, about five times more efficiently when it was incorporated into mixed micelles or liposomes than into emulsions or in the food matrix. Caco-2 cells were able to hydrolyze TAC and to uptake TOL when TAC was incorporated into mixed micelles but not into emulsions.

CONCLUSION

During digestion, most TAC is recovered in matrices where its hydrolysis and its uptake by intestinal cells are markedly less efficient than in mixed micelles.