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Tocotrienols

What do they do? Tocotrienols are members of the vitamin E family. Like vitamin E, tocotrienols are potent antioxidants against lipid peroxidation (the damaging of fats by oxidation).1 2 Human studies indicate that, in addition to their antioxidant activity, tocotrienols have other important functions, especially in maintaining a healthy cardiovascular system.3 Test tube and animal studies indicate a possible role for tocotrienols in protecting against cancer (particularly breast and skin cancer).

Like vitamin E, tocotrienols may offer protection against atherosclerosis (hardening of the arteries) by preventing oxidative damage to LDL cholesterol (oxidation of LDL cholesterol is believed to be one of the triggering factors for atherosclerosis).4 In a double-blind study in patients with severe atherosclerosis of the carotid artery—the main artery supplying blood to the head—tocotrienol administration (200 mg per day) reduced the level of lipid peroxides in the blood. Moreover, in a small sample of patients receiving tocotrienols for 12 months, the size of atherosclerotic plaques became smaller. In contrast, none of the patients receiving the placebo showed an improvement in their atherosclerosis.5

Although tocotrienols inhibited cholesterol synthesis in test tube studies,6 7 human studies have produced conflicting results. In a preliminary study, supplementation with 200 mg of gamma-tocotrienol reduced total cholesterol levels significantly—by 13% in four weeks.8 In a double-blind study, 200 mg of tocotrienols per day produced a significant 15% drop in total cholesterol and an 8% reduction in LDL levels. There were no changes in these levels in the placebo group.9 However, another double-blind study showed that 200 mg of tocotrienols per day failed to lower cholesterol levels.10 In the most recent double-blind study, a group of men with slightly elevated cholesterol levels given 140 mg of tocotrienols and about 120 IU mg of vitamin E daily demonstrated no changes in total cholesterol, LDL cholesterol, or HDL cholesterol levels after four weeks of supplementation.11

Test tube studies indicate that tocotrienols exert some anticancer effects, especially against skin and breast cancer.12 13 14 15 16 These results still need confirmation in human studies, however.

Where are they found? Tocotrienols are found primarily in the oil fraction of rice bran, palm fruit, barley, and wheat germ. Supplemental sources of tocotrienols are derived from rice bran oil and palm oil distillates. Tocotrienol supplements are available in capsules and tablets.

Tocotrienols have been used in connection with the following conditions (refer to the individual health concern for complete information):

Rating Health Concerns
3Stars Atherosclerosis
2Stars High Cholesterol
1Star Stroke
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star An herb is primarily supported by traditional use, or the herb or supplement has little scientific support and/or minimal health benefit.

Who is likely to be deficient? As it is not an essential nutrient, no deficiency state exists.

How much is usually taken? The typical recommendation is 140 to 360 mg per day. Most studies have used 200 mg daily.

Are there any side effects or interactions? No significant adverse effects have been reported with tocotrienols.17

At the time of writing, there were no well-known drug interactions with tocotrienols.

References:

1. Kamal-Eldin A, Appelqvist LA. The chemistry and antioxidant properties of tocopherols and tocotrienols. Lipids 1996;31:671–701 [review].

2. Kamat JP, Devasagayam TPA. Tocotrienols from palm oil as potent inhibitors of lipid peroxidation and protein oxidation in rat brain mitochondria. Neurosci Lett 1995;195:179–82.

3. Theriault A, Chao JT, Wang Q, et al. Tocotrienol: a review of its therapeutic potential. Clin Biochem 1999;32:309–19 [review].

4. Suarna C, Hood RL, Dean RT, Stocker R. Comparative antioxidant activity of tocotrienols and other natural lipid-soluble antioxidants in a homogeneous system, and in rat and human lipoproteins. Biochim Biophys Acta 1993;1166:163–70.

5. Tomeo AC, Geller M, Watkins TR, et al. Antioxidant effects of tocotrienols in patients with hyperlipidemia and carotid stenosis. Lipids 1995;30:1179–83.

6. 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;268:11230–8.

7. Pearce BC, Parker RA, Deason ME, et al. Hypocholesterolemic activity of synthetic and natural tocotrienols. J Med Chem 1992;35:3595–606.

8. Qureshi AA, Bradlow BA, Brace L, et al. Response of hypercholesterolemic subjects to administration of tocotrienols. Lipids 1995;30:1171–7.

9. Qureshi AA, Qureshi N, Wright JJ, et al. Lowering of serum cholesterol in hypercholesterolemic humans by tocotrienols (palmvitee). Am J Clin Nutr 1991;53:1021S–6S.

10. Wahlqvist ML, Krivokuca-Bogetic A, Lo CS, et al. Differential serum response of tocopherols and tocotrienols during vitamin supplementation in hypercholesterolemic individuals without change in coronary risk factors. Nutr Res 1992;12:S181–201.

11. Mensink RP, van Houwelingen AC, Kromhout D, Hornstra G. 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;69:213–9.

12. Goh SH, Hew NF, Norhanom AW, Yadav M. Inhibition of tumour promotion by various palm-oil tocotrienols. Int J Cancer 1994;57:529–31.

13. Yu W, Simmons-Menchaca M, Gapor A, et al. Induction of apoptosis in human breast cancer cells by tocopherols and tocotrienols. Nutr Cancer 1999;33:26–32.

14. Mo H, Elson CE. Apoptosis and cell-cycle arrest in human and murine tumor cells are initiated by isoprenoids. J Nutr 1999;129:804–13.

15. Nesaretnam K, Stephen R, Dils R, Darbre P. Tocotrienols inhibit the growth of human breast cancer cells irrespective of estrogen receptor status. Lipids 1998;33:461–9.

16. He L, Mo H, Hadisusilo S, et al. Isoprenoids suppress the growth of murine B16 melanomas in vitro and in vivo. J Nutr 1997;127:668–74.

17. Theriault A, Chao JT, Wang Q, et al. Tocotrienol: a review of its therapeutic potential. Clin Biochem 1999;32:309–19 [review].