A U-shaped association between selenium intake and cancer risk

Area of Science:

• Nutritional Epidemiology
• Oncology
• Biochemistry

Background:

• Selenium is essential for antioxidant enzymes and human health, but excess intake can be harmful.
• Recommended safe selenium intake levels are not well-established for Asian populations.
• Understanding selenium's role in cancer prevention is crucial, especially in diverse ethnic groups.

Purpose of the Study:

• To investigate the association between dietary selenium intake and the risk of developing various cancers in the Vietnamese population.
• To identify a potentially safe range of daily selenium intake for cancer risk reduction.
• To explore how factors like BMI, smoking, and alcohol consumption modify the selenium-cancer risk relationship.

Main Methods:

• A case-control study involving 3758 cancer cases and 2929 controls in Vietnam.
• Dietary selenium intake was assessed using a semiquantitative food frequency questionnaire.
• Unconditional logistic regression was employed to calculate odds ratios (ORs) and 95% confidence intervals (CIs).

Main Results:

• A significant U-shaped association was observed between selenium intake and overall cancer risk.
• A safe daily selenium intake range was estimated between 110.8–124.4 µg/day (mean 117.8 µg/day).
• Both low (27.8–77.2 µg/day) and high (169.1–331.7 µg/day) selenium intakes were linked to increased cancer risk (OR=3.78 and OR=1.86, respectively).
• The U-shaped association was more pronounced in individuals with lower BMI (<23 kg/m²) and never smokers.
• This pattern was consistent across stomach, colon, rectum, and lung cancers.

Conclusions:

• Dietary selenium intake exhibits a U-shaped association with cancer risk in the Vietnamese population.
• A mean intake of 117.8 µg/day is suggested as a safe level for this population.
• Further research is needed to elucidate the mechanisms underlying the U-shaped relationship between selenium and cancer risk.