Selenomethionine

Best-absorbed selenium form with good tissue incorporation. Same benefits and cautions as selenium supplementation generally.

A rough internal score reflecting quantity, quality, and consistency of human evidence. Not a clinical recommendation.

Pharmacokinetic studies show ~90% absorption versus ~50% for selenite. Used in the SELECT and NPC trials. Stored in body proteins (methionine pool) which provides a selenium reserve.

• Highest bioavailability among selenium forms
• Incorporated into body protein pool as selenium reserve
• Supports all selenoprotein functions

100–200 mcg daily. Most commonly available as 200 mcg capsules.

• Same as selenium generally
• Garlic-like breath at high doses
• GI discomfort

Same toxicity concerns as other selenium forms. Do not exceed 400 mcg/day total selenium intake.

Tissue storage means slower response but also longer washout. Sodium selenite may be preferable when rapid selenoprotein upregulation is needed.

• Immunity60
• Longevity50