Written by Chrystal Moulton, Staff Writer. Delta-tocopherol led to a 2.7 fold increase in tumor cell death.
In previous large-scale human trials, including the Alpha-Tocopherol, Beta Carotene Cancer Prevention Study (ATBC) and Selenium and Vitamin E Cancer Prevention Trial (SELECT), only the alpha-tocopherol was used to test vitamin E’s ability to stop the growth and progression of lung and prostate cancer, respectively. However, results showed that the incidence of either cancer was not reduced with alpha-tocopherol supplementation in either trial. (1,2) This led some people to believe that vitamin E was ineffective against cancer. However, other researchers cited the possible benefits of using other forms of vitamin E to combat cancer development.
In the current study, researchers focused specifically on the effects of delta-tocopherol activity on tumor development.(3)
Ninety mice were divided in to 9 groups containing 10 mice each. The groups are as follows:
- 0.17% gamma-tocopherol + standard diet
- 0.17% delta-tocopherol + standard diet
- 0.17% alpha-tocopherol + standard diet
- 0.17% gamma-tocopherol mixture + standard diet
» Mixture contains 57% gamma-, 24% delta-, 13% alpha-, 1.5% beta-tocopherols
- 0.3% gamma-tocopherol + standard diet
- 0.3% delta-tocopherol + standard diet
- 0.3% alpha-tocopherol + standard diet
- 0.3% gamma-tocopherol mixture + standard diet
» Mixture contains 57% gamma-, 24% delta-, 13% alpha-, 1.5% beta-tocopherols
- Standard Diet
All mice were given the standard diet without supplementation for a week and then were injected with human lung cancer cells. On the same day they were injected, each group was given the assigned diet for 49days or until the size of their tumor reached 1000mm3. Twice a week, researchers monitored the size of the tumors as well as the body weight and food intake of the mice in each group. Upon completion of the trial, tumors were analyzed and tissue and serum levels of the different forms of vitamin E were recorded.
Results demonstrated delta-tocopherol as most effective in stopping tumor growth followed by the gamma-tocopherol mixture, and finally the gamma-tocopherol alone. Final tumor weight of the delta-tocopherol group was significantly lower than control (p<0.05). Delta-Tocopherol also significantly reduced the number of cells undergoing oxidative stress and increased the death of tumor cells by 2.7fold (p<0.01). Throughout the study, researchers found that alpha-tocopherol did not show any benefit to inhibiting the cancerous growth or promoting death of cancer cells. The effective dose of delta-tocopherol at 0.17% and 0.3% concentration in the mouse diet is approximately equivalent to an 800mg and 1300mg dose in humans, respectively.
In this study, researchers, actually, expected that gamma-tocopherol would be more effective against the tumors and were a bit surprised by the results. They agreed however that more research will be needed to further confirm the present findings.
Source: Li, Guang-Xun, et al. “δ-tocopherol is more active than α-or γ-tocopherol in inhibiting lung tumorigenesis in vivo.” Cancer Prevention Research 4.3 (2011): 404-413.
© 2017 American Association for Cancer Research
Posted April 21, 2014.
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.
- Li GX, et al. δ-tocopherol is more active than α – or γ -tocopherol in inhibiting lung tumorigenesis in vivo. Cancer Prev Res (Phila). 2011 Mar;4(3):404-13.
