What is the recommended dosage for Selenium?

General: 55 mcg/day; Cardiovascular Antioxidant: 100-200 mcg/day

What are the side effects of Selenium?

Potential side effects include: Selenosis at high doses (garlic breath odor, hair/nail loss, nausea), GI discomfort at moderate-high doses, Potential increased type 2 diabetes risk at high supplemental doses.

What is selenium and how may it relate to cardiovascular health?

Selenium is a trace mineral that functions as a component of glutathione peroxidase and other selenoproteins with antioxidant roles. Observational studies suggest a U-shaped relationship between selenium levels and cardiovascular risk, where both deficiency and excess may be harmful. Supplementation is most relevant for selenium-deficient populations.

What dosage of selenium has been studied for cardiovascular outcomes?

Clinical trials have used 100–200 mcg of selenium per day, primarily as selenomethionine or sodium selenite. The SELECT trial found no cardiovascular benefit from 200 mcg selenium daily. The RDA is 55 mcg, and the tolerable upper intake level is 400 mcg. Adequate selenium status may be achievable through diet alone in many populations.

What are the potential side effects of selenium supplements?

Chronic selenium excess (selenosis) causes garlic breath odor, hair loss, nail brittleness, nausea, and fatigue. The tolerable upper intake level is 400 mcg daily. High selenium status has been associated with increased type 2 diabetes risk in some studies. Selenium supplementation is not recommended for populations with adequate intake.

Selenium

mineral

Also known as: Selenomethionine, Sodium Selenite, Selenium Yeast, L-Selenomethionine

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About

Selenium is an essential component of glutathione peroxidases, the primary enzymatic antioxidant defense against lipid peroxidation in vascular tissue. The KiSel-10 trial (443 elderly participants, 4 years) found combined selenium (200 mcg/day) and CoQ10 reduced cardiovascular mortality by 54%, with effects persisting for 12 years. A U-shaped dose-response exists: serum selenium of 120-150 mcg/L appears optimal.

How It Works

Essential component of selenoprotein P and glutathione peroxidases (GPx) — the primary enzymatic antioxidant defense against lipid peroxidation and LDL oxidation in vascular tissue; thioredoxin reductases regulate vascular redox signaling; selenoprotein S modulates endoplasmic reticulum stress in cardiomyocytes; adequate selenium status supports thyroid function influencing cardiac output.

Evidence For Conditions

Condition	Grade	Studies	Participants
Oxidative Stress (Cardiovascular)	B	3	600	View →
Coronary Artery Disease (CAD)	C	5	10000	View →

Side Effects

Selenosis at high doses (garlic breath odor, hair/nail loss, nausea)
GI discomfort at moderate-high doses
Potential increased type 2 diabetes risk at high supplemental doses

Drug & Supplement Interactions

Cisplatin and other chemotherapy drugs (may affect efficacy)
Statins (may enhance antioxidant effects)
CoQ10 (synergistic cardiovascular benefit — KiSel-10 combination)

Always inform your healthcare provider about all supplements you take.

Related Ingredients

Calcium Magnesium Potassium

Quick Facts

Dosage: General: 55 mcg/day; Cardiovascular_Antioxidant: 100-200 mcg/day
Forms: capsule tablet
Natural Sources: Brazil nuts (1-2 nuts provide daily requirement), Seafood, Organ meats, Whole grains, Eggs, Sunflower seeds
Upper Limit: 400 mcg/day (risk of selenosis above this level)
Best Time: With meals

Evidence Summary

Oxidative Stress (Cardiovascular) B

Coronary Artery Disease (CAD) C

FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. The products and information on this website are not intended to diagnose, treat, cure, or prevent any disease. The evidence grades presented are based on our analysis of published peer-reviewed research and do not constitute medical advice. Always consult your healthcare provider before starting any supplement regimen.