VITAMIN-E BIOPOTENCY - COMPARISON OF VARIOUS NATURAL-DERIVED AND CHEMICALLY-SYNTHESIZED ALPHA-TOCOPHEROLS

The difference in bioactivity between d- and dl- forms of alpha-tocoph erol is reflected in the currently established United States Pharmacop oeia Standards for vitamin E activity. Current evidence strongly suppo rts the concept that the presently accepted values assigned to the d- and dl- forms of alpha-tocopherol and corresponding acetate esters are valid for application to farm animals. Consequently, there is no know n advantage to supplementing animal feeds with d- forms of vitamin E ( alpha-tocopherol) so long as what is supplemented is provided in Inter national Units and not in milligrams.