The controversy between natural and synthetic vitamin E
« The controversy between natural and synthetic vitamin E », MAHAN, 2009
Alpha tocopherol is the form of vitamin E with the strongest activity in the animal organism. Two sources exist: the natural one and the synthetic one. Natural alpha tocopherol is composed of a RRR-alpha-tocopherol molecule. The synthetic form is racemic, in other words, it is composed of a mixture of 8 isomers (allrac- α-tocopherol: RRR, RRS,RSR, RSS, SSS, SSR, SRS).
In 1999, the United States Pharmacopeia published the International Unit (I.U) value to compare the two sources of vitamin E. Using rat fetal studies, it was showed that natural source has 36% more biological activity than the synthetic source with the same amount. The Official Journal of the European Union followed these equivalences. They were published the 14th of January 2011 (N°26/2011): 1mg of α-tocopheryl acetate completely racemic = 1 IU, 1mg of RRR-α- tocopheryl acetate = 1.36 IU and 1 mg of RRR-α-tocopherol=1.49 IU.
Differents studies in sows, piglets and pigs, showed that the biological activity from natural vitamin E is underestimated. In sow, 1.61, 1.89, and 1.58 ratios were calculated respectively in serum, liver and colostrum. In piglets, vitamin E intake is very important because their growth rate is fast and their vitamin E storage decreases quickly. The piglets do not have the required digestive enzymes to hydrolyze acetate forms. Consequently, piglets are dependent on sow milk quality or on no-acetate vitamin E intake from feed.
In finisher pigs, two studies have investigated the equivalence ratio of natural vs. synthetic vitamin E.
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The first study (Yang et al. 2009) has clearly demonstrated 2.64, and 2.2 for the heart muscle and the kidney respectively. Other tissues were evaluated and with the same general trend. The second trial (Boler et al. 2009) with finisher pigs, used 200 IU natural vitamin E for a group and the same level of synthetic vitamin E (200 IU) for the other group. The results showed that the pigs fed with natural vitamin E, had less oxidative pork chop damage. These last studies confirmed that 1.36 ratio underestimates biological activity of natural vitamin E. A ratio between 1.75 and 2.25 seems to be more adequate.
