• ]]>Cancer Prevention]]>, ]]>Heart Disease Prevention]]>, ]]>High Cholesterol]]>
Tocotrienols are fat-soluble substances closely related to vitamin E. Like vitamin E, they have ]]>antioxidant properties]]> , and help protect fatty substances in the body from being damaged by free radicals. In the 1990s, antioxidant supplements were thought to offer great potential for preventing a variety of diseases, including cancer and heart disease, and on this basis tocotrienols were offered on the market as healthful supplements. Tocotrienols have also been proposed for reducing cholesterol. However, subsequent studies have tended to pour cold water on all these hopes. At present, there is no reliable evidence that tocotrienols offer any meaningful health benefits.
Tocotrienols are not essential nutrients. They occur naturally in the oil extract of barley, palm fruit, rice bran, and wheat germ. Most commercially available supplements are made from rice bran oil or palm oil.
While test-tube studies]]> , ]]>animal studies]]> , and ]]>open human trials]]> seemed to suggest that tocotrienols can correct ]]>high cholesterol]]> , ]]>9-21,25]]> properly designed studies failed to find benefit. ]]>22-24]]>
Test-tube and animal studies, as well as one double-blind human trial have found promising hints that tocotrienols may help prevent cancer. ]]>1-8,26]]> The double-blind study among these specifically found that tocotrienols might help prevent DNA damage, which could, in theory, help prevent many disease associated with aging, not just cancer. ]]>26]]> However, none of this evidence rises above the level of "highly preliminary."
The hypothesis that tocotrienols can prevent heart disease simply by virtue of their antioxidant actions has lost favor, since the same hypothesis proved incorrect with ]]>vitamin E]]> and ]]>beta-carotene]]> .
The bottom line: The health benefits of tocotrienols, if there are any, remain to be established.
1. Qureshi AA, Mo H, Packer L, et al. Isolation and identification of novel tocotrienols from rice bran with hypocholesterolemic, antioxidant, and antitumor properties. J Agric Food Chem . 2000;48:3130–3140.
10. O'Byrne D, Traber MG, Packer L, et al. Supplementation with alpha-tocotrienyl acetate enhances LDL oxidative resistance without lowering serum cholesterol in hypercholestrolemic humans [abstract]. FASEB J . 1999;13:A536.
11. Parker RA, Pearce BC, Clark RW, et al. Tocotrienols regulate cholesterol production in mammalian cells by post-transcriptional suppression of 3-hydroxy-3-methylglutaryl-coenzyme A reductase. J Biol Chem . 1993;268:11230–11238.
15. Qureshi AA, Qureshi N, Hasler-Rapacz JO, et al. Dietary tocotrienols reduce concentrations of plasma cholesterol, apolipoprotein B, thromboxane B2, and platelet factor 4 in pigs with inherited hyperlipidemias. Am J ClinNutr . 1991;53(4 suppl):1042S–1046S.
17. Qureshi AA, Sami SA, Salser WA, et al. Synergistic effect of tocotrienol-rich fraction (TRF 25) of rice bran and lovastatin on lipid parameters in hypercholesterolemic humans. J Nutr Biochem . 2001;12:318–329.
20. Wan Nazaimoon WM, Sakinah O, Gapor A, et al. Effect of palm olein tocopherol and tocotrienol on lipid peroxidation, lipid profiles and glycemic control in non-insulin diabetes mellitus patients. Nutr Res . 1996;16:1901–1911.
22. Mustad VA, Smith CA, Ruey PP, et al. Supplementation with 3 compositionally different tocotrienol supplements does not improve cardiovascular disease risk factors in men and women with hypercholesterolemia. Am J Clin Nutr . 2002;76:1237–43.
23. Kerckhoffs DA, Brouns F, Hornstra G, Mensink RP. Effects on the human serum lipoprotein profile of beta-glucan, soy protein and isoflavones, plant sterols and stanols, garlic and tocotrienols. J Nutr . 2002;132:2494–505.
24. Mensink RP, van Houwelingen AC, Kromhout D, et al. A vitamin E concentrate rich in tocotrienols had no effect on serum lipids, lipoproteins, or platelet function in men with mildly elevated serum lipid concentrations. Am J Clin Nutr . 1999;69:213–219.
25. Ajuluchukwu JN, Okubadejo NU, Mabayoje M, et al. Comparative study of the effect of tocotrienols and -tocopherol on fasting serum lipid profiles in patients with mild hypercholesterolaemia: a preliminary report. Niger Postgrad Med J . 2007;14:30-3.
Last reviewed April 2009 by EBSCO CAM Review Board]]>
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