Vitamin E has been savaged in the media and suffered in the marketplace because of studies that fail to properly assess the full spectrum of tocopherols and tocotrienols. Sharon Ling sets the record straight.
The vitamin E family comprises eight different compounds, or isomers: four tocopherols and four tocotrienols (alpha, beta, gamma and delta). Alpha-tocopherol has been the focus of early research and is the most common known form of vitamin E. Tocotrienols differ from tocopherols by having an unsaturated side tail that results in significantly different biological activities.
In nature, most plants, fruits and vegetables contain a mixture of tocopherols and tocotrienols — a single isomer of vitamin E rarely ever occurs in isolation naturally. Whilst tocopherols occur naturally in common vegetable oils, tocotrienols are concentrated in cereal grains such as oat, barley and rice bran, as well as virgin crude palm oil, which is the richest source in nature.
Recently, several large-scale clinical trials (GISSI Prevention Trial, HOPE & HOPE-TOO Trial, Women's Health Study, Physician's Health Study II) reported that vitamin E did not protect against cardiovascular diseases.1,2,3,4 On closer examination, all the studies used alpha-tocopherol alone, and in some cases used the synthetic form of alpha-tocopherol. Synthetic vitamin E is chemically produced from petroleum byproducts. The synthetic form is a mixture of eight stereoisomers referred to as all-rac-alpha-tocopherol (d,l-alpha-tocopherol). Only one of these stereoisomers is bio-identical to natural alpha-tocopherol (RRR-alpha-tocopherol or d-alpha-tocopherol). Natural alpha-tocopherol has better bioavailability compared to the synthetic form. Taking an identical dosage, the concentration of natural alpha-tocopherol in blood and organ is almost double those of the synthetic form.5
Even natural alpha-tocopherol may not be as 'natural' as one would have thought, since natural mixed tocopherols are converted to single alpha-tocopherol by a chemical process called methylation. In addition, taking too much alpha-tocopherol depletes the body of other vitamin E isomers, especially gamma-tocopherol.6
It is only in recent years that the unique cardiovascular health benefits of tocotrienols not shared by tocopherols were revealed by new studies. Alpha-tocotrienol was found to be 40-60 times more potent than alpha-tocopherol as an antioxidant.7 Tocotrienols showed promising cardioprotective properties including lowering blood cholesterol,8,9,10 reversing atherosclerosis,11 reducing platelet aggregation,8,9,10,12 inhibiting expression of adhesion molecules and adhesion to monocytes,13 lowering blood pressure,14 and reducing arterial stiffness.15
One of the recent human studies looked into the cardiovascular risk factor arterial stiffness, which is a predictor of cardiovascular events not only in diseases but also in normal subjects.15,16,17 Data from this randomized, controlled clinical trial demonstrated that Tocomin SupraBio (a patented, bioenhanced, natural, full-spectrum palm tocotrienol complex from Carotech) reduced arterial stiffness in healthy adults after two months of oral supplementation.15As arterial stiffness is an independent risk factor of cardiovascular diseases, it is conceivable that improvement in arterial compliance may reduce the risk of contracting these diseases.
In another study, researchers at the University of Connecticut School of Medicine used various isomers of tocotrienols (supplied by Carotech) to study the effects and mechanism of tocotrienols' cardioprotective function, especially on their ability to improve post-ischemic ventricular function and reduce myocardial infarct size in rats.
The results showed that all forms of tocotrienols (the palm tocotrienol complex and individual tocotrienol isomers) provided significant cardioprotection. Gamma-tocotrienol was found to be the most cardioprotective isomer.18
Quite apart from its unique qualities in cardiovascular health, numerous studies have also shown that tocotrienols possess neuroprotective properties,19 anticancer properties as revealed in breast cancer studies,20 and protection against premature skin aging from UV exposure.21 It is, therefore, no surprise that tocotrienol is currently one of the most intensively investigated substances in health care-related research.
Sharon Ling has been an investigator in more than 30 human clinical trials, many related to palm-based phytonutrients. She is regional sales manager (Europe) for natural vitamin E supplier, Carotech, Inc. www.carotech.net
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15. Rasool AH et al. Arterial Compliance and vitamin E blood levels with a self emulsifying preparation of tocotrienol rich vitamin E. Arch Pharm Res. 2008; 31 (9); 1212-1217.
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17. Willum-Hansen T, et al. Prognostic value of aortic pulse wave velocity as index of arterial stiffness in the general population. Circulation 2006; 113(5):664-70.
18. Das S, et al. Cardioprotection with palm tocotrienols: Comparison of different isomers. Am J Physiol Heart Circ Physiol, 2008; 294, H970 - 978
19. Khanna S, et al. Neuroprotective properties of the natural vitamin E a-tocotrienol. Stroke 2005; 36, e144-e152.
20. Guthrie N et al. Inhibition of proliferation of estrogen-receptor-negative MDA-MB-435 and ?positive MCF-7 human breast cancer cells by palm tocotrienols and Tamoxifen, alone and in combination. Journal of Nutrition 1997; 127:544S-548S.
21. Dr. Nicholas V Perricone, Method and Compositions for Topical Application to the Skin for Prevention and/or Treatment of Radiation-Induced Skin Damage, U.S. Patent No: 5376361 (1994).