Cancer prevention by tocopherols and tea polyphenols

Area of Science:

• Nutritional biochemistry
• Cancer prevention research
• Pharmacology

Background:

• Tocopherols (vitamin E) and tea polyphenols are investigated for cancer preventive properties.
• High-dose alpha-tocopherol trials in humans yielded disappointing outcomes.
• Previous research indicates varying efficacy among different tocopherol forms.

Purpose of the Study:

• To review the cancer preventive activities of different tocopherol isomers and green tea polyphenols.
• To discuss potential mechanisms of action for these compounds.
• To evaluate the evidence for cancer prevention in both animal models and human studies.

Main Methods:

• Review of existing scientific literature and data.
• Analysis of results from animal models of carcinogenesis.
• Examination of findings from human clinical trials.

Main Results:

• Beta- and gamma-tocopherols inhibit carcinogenesis in animal models for colon, lung, mammary, and prostate cancers.
• Alpha-tocopherol showed ineffectiveness in both animal and human studies.
• Green tea polyphenols demonstrate broad cancer preventive activity in animal models, with proposed mechanisms.

Conclusions:

• Specific tocopherol isomers, not alpha-tocopherol, show promise in preclinical cancer models.
• The cancer preventive role of green tea in humans requires further rigorous investigation.
• Translating findings from animal models to human cancer prevention remains a significant challenge.