The vitamin E forms were also linked to a significant reduction in levels of a marker of pathogenesis and progression of certain breast cancers called human epidermal growth factor receptor 2 (HER-2), according to findings published in Carcinogenesis.
“In this paper, we demonstrate for the first time the anticancer activity of annatto-T3 supplementation in a spontaneous breast tumor model,” wrote the researchers, led by Mauro Provinciali from IRCCS-INRCA in Ancona, Italy.
“Although vitamin E (both tocopherols and tocotrienols) is known as a potent antioxidant, the antitumor activity of vitamin E may not be associated with its antioxidant activity,” they explained.
“Rather, we have found an increased oxidative stress in tumor cells treated with annatto- tocotrienols. The annatto-tocotrienol-dependent increased [reactive oxygen species] may be involved in the activation of both apoptosis and senescent-like growth arrest in tumor cells. Our results agree with the pro-oxidant effect of analogs of vitamin E.”
The vitamin E family
Tocotrienols are forms of vitamin E that have traditionally been in the shadow of the more popular vitamin E form – tocopherols.
Overall, there are eight forms of vitamin E: Four tocopherols (alpha, beta, gamma, delta) and four tocotrienols (alpha, beta, gamma, delta). Alpha-tocopherol (alpha-Toc) is the main source found in supplements and in the European diet, while gamma-tocopherol (gamma-Toc) is the most common form in the American diet.
Tocotrienols are only minor components in plants, although several sources with relatively high levels include palm oil, annatto, cereal grains and rice bran.
The new study used American River Nutrition’s DeltaGold product – a naturally tocopherol-free mix containing ~90% delta- and 10% gamma-tocotrienol.
Provinciali and his co-workers investigated the effects of the annatto-tocotrienols on the spontaneous development of mammary tumors in HER-2/neu transgenic mice, an aggressive form of the disease found in 20-30% of metastatic breast cancers.
Animals received 0, 50 or 100 mg/kg of annatto-tocotrienols in olive oil three times per week.
Results showed a dose-dependent inhibition of cell growth and increased cell death (apoptosis) of the cancer cells. An increase in reactive oxygen species was also observed
The researchers also noted a rapid increase of delta-tocotrienol in the serum, liver, and tumors of the mice, supporting the bioavailability of the nutrient.
Commenting on the study's findings, Dr Barrie Tan, president of Massachusetts-based American River Nutrition, told us: “When compared neck-to-neck, the effect of annatto tocotrienol is in fact that of delta-tocotrienol.
“Other studies from cell lines, animals and humans point to delta-tocotrienol tissue bioavailability without physical/chemical enhancement like emulsification.”
Published online ahead of print, doi: 10.1093/carcin/bgt064
“Effect of annatto tocotrienols supplementation on the development of mammary tumors in HER-2/neu transgenic mice”
Authors: Pierpaoli E., Viola V., Barucca A., Orlando F., Galli F., Provinciali M.