Taking Vitamin E for Disease Prevention? Which Isomer?

In an article referenced in the CAS databases available in SciFinder and on STN, researchers from the Brigham and Women's Hospital in Boston reported their findings on long-term vitamin E or C supplementation and risk of heart attacks and stroke in men:

Sesso, H.D.; Burning, J.E.; Christen, W.G.; Kurth, T.; Belanger, C.; MacFadyen, J.; Bubes, V.; Manson, J.E.; Glynn, R.J.; Gaziano, J.M.
Vitamin E and C in the Prevention of Cardiovascular Disease in Men. J. Am. Med. Assoc. 2008, 300(18), 2123-2133.

They found that "neither vitamin E nor vitamin C supplementation reduced the risk of major cardiovascular events" in a group of nearly 15,000 male participants after an average of 8 years of supplementation. Two weeks earlier, the National Cancer Institute announced that preliminary analysis of data from a large human study indicated that vitamin E does not prevent prostate cancer.1 Based on these discouraging findings, why is it important to continue studying vitamin E for disease prevention?

Participants in these studies were given a form of vitamin E known as alpha-tocopherol.2 While there is significant justification for studying alpha-tocopherol, information in the CAS databases suggests that additional forms of vitamin E should be considered for disease prevention. In fact, the term "vitamin E" refers to eight natural isomers:

Name: alpha-tocopherol
CAS Registry Number(R): 59-02-9

Name: beta-tocopherol
CAS Registry Number(R): 148-03-8

Name: gamma-tocopherol
CAS Registry Number(R): 54-28-4

Name: delta-tocopherol
CAS Registry Number(R): 119-13-1


Name: alpha-tocotrienol
CAS Registry Number(R): 1721-51-3

Name: beta-tocotrienol
CAS Registry Number(R): 490-23-3

Name: gamma-tocotrienol
CAS Registry Number(R): 14101-61-2

Name: delta-tocotrienol
CAS Registry Number(R): 25612-59-3

The following review articles referenced in the CAS databases summarize the literature on gamma-tocopherol, the form of vitamin E most commonly consumed in the typical U.S. diet:

Dietrich, M.; Traber, M.G.; Jacques, P.F.; Cross, C.E.; Hu, Y.; Block, G. Does Gamma-Tocopherol Play a Role in the Primary Prevention of Heart Disease and Cancer? A Review. J. Am. Coll. Nutr. 2006, 25(4), 292-299.

Jiang, Q.; Christen, S.; Shigenaga, M.K.; Ames, B.N. Gamma-Tocopherol, the Major Form of Vitamin E in the US Diet, Deserves More Attention. Am. J. Clin. Nutr. 2001, 74, 714-722.

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