Researchers from the University of Texas M.D. Anderson Cancer Center report that intakes of vitamin E in the alpha-tocopherol form were associated with consistent and independent reductions in lung cancer risk. Other forms of the vitamin did not have any effects on their own, they added.
“To the best of our knowledge, this is the first study to compare dietary intakes of the different forms of tocopherols (alpha-, beta-, gamma and delta-tocopherol) and lung cancer risk,” wrote lead author Somdat Mahabir in the International Journal of Cancer.
“Our large lung cancer case-control study adds meaningful data on alpha-, gamma-, beta- and delta-tocopherol to the literature,”
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.
Study details
Mahabir and co-workers report results from an ongoing study involving 1,088 patients with lung cancer (average age 61.7) and 1,414 healthy controls (average age 60.8). Dietary intakes were assessed using a modified version of the 135-item National Cancer Institute’s Health Habits and History Questionnaire Food Frequency Questionnaire. Demographic and lifestyle data were also collected, including smoking habits.
The researchers calculated that the highest average intakes of alpha-tocopherol (more than 7.73 mg per day) were associated with a 53 per cent reduction in lung cancer risk, compared to the lowest average intakes (less than 4.13 mg per day). This result took into account the other forms of tocopherols.
When the researchers accounted for the other tocopherols they observed no significant associations on lung cancer risk for beta-, gamma, and delta-tocopherol.
Considering all the tocopherols together, the highest average intake (more than 12.95 mg per day) was associated with a 55 per cent reduction in the risk of lung cancer, compared to the lowest average intakes (less than 6.68 mg per day), said the researchers.
“We found consistent independent associations for increased dietary alpha-tocopherol intake and risk reduction but did not find independent associations for gamma-, beta- and delta-tocopherol in lung cancer risk,” wrote Mahabir.
“Our data should be useful in stimulating additional epidemiologic and basic science research in the relationship of different forms of vitamin E and cancer.”
No mechanistic study was performed by the researchers, and they make no discussion of it in their article.
Lung cancer is the most common form of cancer worldwide with over 1.2m new cases diagnosed annually, according to the European School of Oncology. It has one of the lowest survival rates with only 25 per cent of patients surviving more than one year after diagnosis (England and Wales).
Source: International Journal of CancerVolume 123, Pages 1173-1180“Dietary alpha-, beta-, gamma- and delta-tocopherols in lung cancer risk”Authors: S. Mahabir, K. Schendel, Y.Q. Dong, S.L. Barrera, M.R. Spitz, M.R. Forman