Selenium and its relationship to cancer: an update

Area of Science:

• Biochemistry
• Nutritional Science
• Oncology

Background:

• Selenomethionine (Semet) and Se-methylselenocysteine (SeMCYS) are key selenium compounds found in various foods.
• Epidemiological studies suggest a link between selenium intake and reduced cancer risk.
• Lower blood selenium levels are often observed in cancer patients, though toenail selenium data is inconsistent.

Purpose of the Study:

• To review the role of different selenium compounds in cancer prevention.
• To evaluate the efficacy of selenium in human and animal cancer studies.
• To explore proposed mechanisms of selenium's anti-cancer effects.

Main Methods:

• Review of epidemiological studies on selenium intake and cancer.
• Analysis of human clinical trials investigating selenium's effect on cancer incidence and biomarkers.
• Examination of small-animal studies on selenium and tumor reduction.
• Comparison of the efficacy of Semet and SeMCYS in cancer models.

Main Results:

• Most human trials (7 out of 8) and numerous animal studies indicate a beneficial effect of selenium in reducing cancer incidence or biomarkers.
• Se-enriched yeast is commonly used in human trials.
• Se-methylselenocysteine (SeMCYS) demonstrated significant effectiveness in reducing mammary tumors in animal models.

Conclusions:

• Selenium intake is associated with a reduced incidence of certain cancers.
• Se-methylselenocysteine (SeMCYS) is a highly effective seleno-compound for reducing mammary tumors.
• Further research may be needed to determine the optimal selenium compound for different cancer types, such as colon tumors.