Safety Profile
Overall safety rating: Generally Safe
Selenium Side Effects & Safety
This content is for informational purposes only and does not constitute medical advice. Consult your healthcare provider before starting any supplement. Full disclaimer
Potential Side Effects
- Garlic breath odor at higher doses
- Nausea and diarrhea (uncommon at recommended doses)
- Selenosis at chronic doses >400mcg/day: hair loss, nail brittleness, fatigue, irritability
- Possible increased type 2 diabetes risk at high doses (>200mcg/day) per SELECT trial data
Drug & Supplement Interactions
- May enhance the anticoagulant effect of warfarin
- Cisplatin and other chemotherapy drugs — selenium may alter drug metabolism
- Statins — selenium may have additive cholesterol-lowering effects
- Vitamin C taken simultaneously may reduce selenium absorption — separate by 30 minutes
Maximum Dose
Do not exceed: 400mcg/day (NIH UL); chronic intake above this causes selenosis
References
- Lippman SM, Klein EA, Goodman PJ, et al. (2009). Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. DOI PubMed
- Wichman J, Winther KH, Bonnema SJ, Hegedus L (2016). Selenium supplementation significantly reduces thyroid autoantibody levels in patients with chronic autoimmune thyroiditis: a systematic review and meta-analysis. Thyroid. DOI PubMed
- Thomson CD, Chisholm A, McLachlan SK, Campbell JM (2008). Brazil nuts: an effective way to improve selenium status. American Journal of Clinical Nutrition. DOI PubMed