Written by Chrystal Moulton, Staff Writer. Delta-tocopherol significantly reduces lipid oxidation by 56.9%.
Vitamin E exists in different forms and varying levels within body tissues. It is an effective tool used in trapping oxidant species, which causes damage to body tissues over time. Among the many forms of vitamin E that exist, alpha-tocopherol is the most abundant form found and preferentially stored in the body. Many studies have investigated the effects of alpha-tocopherol in common chronic ailments such as cancer. (1,2) However, results of these studies make it difficult to draw any conclusion about the effect of alpha-tocopherol in preventing cancer.(1,2) In the current study, the author researches the effect of alpha-tocopherol versus other forms of vitamin E in prevention and inhibition of pre-cancerous glands. (3)
In an 8-week animal trial, groups of 10 rats, that were chemically induced to develop colon cancer, were assigned to receive either:
- Baseline diet containing 33 IU vitamin e (as alpha-tocopheryl acetate) [nutritional requirement for animal studies]
- Baseline diet supplemented with 0.2% alpha-tocopherol
- Baseline diet supplemented with 0.2% gamma-tocopherol
- Baseline diet supplemented with 0.2% delta-tocopherol
- Baseline diet supplemented with 0.2% gamma-tocopherol rich mixture (57% gamma-, 24% delta-, 13% alpha-, 1.5% beta-tocopherol)
Another group of rats that were not chemically induced were also given the baseline diet. They served as a negative control group.
After 8 weeks, researchers tested each animal for inhibition of pre-cancerous glands called aberrant crypt foci. These abnormal clusters of glands, thought to be precursors of polyps, can lead to colon cancer. Researchers also tested for inflammatory markers.
Researchers noticed that there was competition between the various forms of the vitamin E when they observed serum samples from the rats. Even more, they also observed high levels of gamma and delta-tocopherol metabolites and few metabolites of alpha-tocopherol indicating alpha-tocopherol was stored while other forms were readily broken down. Nonetheless, results from the trial showed that all forms of vitamin E significantly reduced the amount of aberrant crypt foci in the animals except alpha-tocopherol. Among the various forms, delta-tocopherol was most efficient in reducing the number of aberrant crypt foci (62.3%, p<0.05) compared to control. Delta-tocopherol also significantly reduced lipid oxidation by 56.9% followed by gamma- tocopherol at 39.9% (p<0.05). Gamma and delta-tocopherol along with the gamma-tocopherol rich mixture significantly stopped the loss of a receptor on the cancerous cells important for cell growth, death, and differentiation (p<0.05). Alpha-tocopherol showed no significant effects on the loss of this receptor. Also, gamma- tocopherol was most efficient in decreasing markers of inflammation particularly prostaglandin E2 (p<0.05).
Table 1. Effective serum and tissue levels in rats
| Rat | Human | |
| Serum (μM) | ||
| gamma-Tocopherol | 21.20 ± 9.56 | ~3.43 |
| delta-Tocopherol | 6.69 ± 3.63 | ~1.08 |
| Colon (nmol/g) | ||
| gamma-Tocopherol | 21.49 ± 3.26 | ~3.48 |
| delta-Tocopherol | 16.91 ± 7.11 | ~2.74 |
*Tissue and serum samples of 5 rats from each group were analyzed. All rat values are significant (p<0.01). Values were translated to human however, whether these values represent a significant effect in humans could not be determined.
Overall the data shows that delta-tocopherol may be very effective in combating abnormalities linked to development of colon cancer. However, the author states: Whether delta-tocopherol is still more active in cancer prevention under other experimental conditions remains to be determined.
Source: Guan, Fei, et al. “δ-and γ-tocopherols, but not α-tocopherol, inhibit colon carcinogenesis in azoxymethane-treated F344 rats.” Cancer Prevention Research 5.4 (2012): 644-654
© 2012 American Association for Cancer Research.
Posted April 14, 2014.
Chrystal Moulton BA, PMP, is a 2008 graduate of the University of Illinois at Chicago. She graduated with a bachelor’s in psychology with a focus on premedical studies and is a licensed project manager. She currently resides in Indianapolis, IN.
References:
- Klein EA, et al. Vitamin E and the risk of prostate cancer: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2011 Oct 12;306(14):1549-56.
- Albanes D, et al. Effects of alpha-tocopherol and beta-carotene supplements on cancer incidence in the Alpha-Tocopherol Beta-Carotene Cancer Prevention Study. Am J Clin Nutr. 1995 Dec;62(6 Suppl):1427S-1430S.
- Guan F, et al. δ- and γ-tocopherols, but not α-tocopherol, inhibit colon carcinogenesis in azoxymethane-treated F344 rats. Cancer Prev Res (Phila). 2012 Apr;5(4):644-54.
