Current Insights and Research Gaps in Selenium Supplementation for Metabolic Health: A Scoping Review

Area of Science:

• Nutritional Biochemistry
• Metabolic Health
• Inflammation & Oxidative Stress

Background:

• Selenium is vital for metabolic health, antioxidant defense, and inflammation modulation.
• Understanding selenium's physiological roles and pathological relevance is crucial for therapeutic supplementation strategies.
• Current knowledge gaps hinder the establishment of safe and effective selenium dosing guidelines.

Purpose of the Study:

• To systematically map and synthesize evidence on selenium supplementation's effects on inflammation, oxidative stress, and glucose-lipid metabolism in adults.
• To identify knowledge gaps related to selenium supplementation and metabolic health.
• To inform the development of evidence-based selenium dosing guidelines.

Main Methods:

• A scoping review was conducted following PRISMA-ScR guidelines.
• Searched major electronic databases for clinical trials evaluating selenium supplementation's impact on metabolic disease markers in adult populations.
• Included studies assessing inflammation, oxidative stress, and glucose-lipid metabolism.

Main Results:

• Selenium supplementation improved metabolic markers, notably reducing insulin resistance (up to 26% decrease in HOMA-IR) and inflammation (up to 62.4% decrease in hs-CRP) in studies of 12 weeks or longer.
• Benefits were most pronounced in adults with diabetes and insulin resistance.
• Effects were equivocal in polycystic ovary syndrome (PCOS) and postmenopausal women, with some studies showing neutral or adverse effects.

Conclusions:

• Selenium supplementation can enhance insulin sensitivity, lower hs-CRP, and boost antioxidant defenses, especially in adults with diabetes or insulin resistance.
• The therapeutic window for selenium is narrow; dosing must be guided by baseline selenium status to avoid deficiency or excess.
• Further long-term, well-controlled trials are necessary to define optimal selenium regimens and identify specific populations that benefit most from supplementation.