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Added: 10/28/2009
A new study from Japan reports that tocotrienols, members of the vitamin E family, may exert their anti-cancer benefits by accumulating in cancer cells and delaying tumor growth. Both gamma- and delta-tocotrienols may accumulate in cancer cells and promote the death of the tumors, according to data from in vitro and in vivo studies by researchers from Kyushu University in Japan.
The potential anti-cancer benefits of tocotrienols are not new, but the Japanese researchers claim that their study is the first to show accumulation of the compounds in cancer cells. "These results, to our knowledge, are the first demonstration of specific accumulation of gamma-tocotrienols and delta-tocotrienols in tumors and suggest that tocotrienol accumulation is critical for the anti-tumor activities of tocotrienols," wrote lead author Yuhei Hiura in The Journal of Nutritional Biochemistry.
There are eight forms of vitamin E: four tocopherols (alpha, beta, gamma, delta) and four tocotrienols (alpha, beta, gamma, delta). Alpha-tocopherol is the main source found in supplements and in the European diet, while gamma-tocopherol is the most common form in the American diet.
The Japanese researchers studied the effects of gamma- and delta-tocotrienol on mouse cancer cells (murine hepatoma MH134) both in vitro and in vivo. For the cell study, the tumor cells were cultured in the tocotrienols, and they found that the delta-version inhibited cell growth more than the gamma-type. This was related to an induction of apoptosis (programmed cell death).
For the animal studies, the researchers used C3H/HeN mice and implanted the tumor cells. The animals were then fed a normal diet, or the diet supplemented with 0.1 percent gamma-tocotrienol or 0.1 percent delta-tocopherol for four weeks.
At the end of the study, a significant delay in tumor growth was observed for both groups supplemented with the tocotrienols. No effects on body weight were recorded. "In conclusion, our results suggested that accumulation is critical for the anti-tumor activity of tocotrienols," researchers said.
The Journal of Nutritional Biochemistry Published online ahead of print.
