Selenium Amino Acid Chelate vs. Sodium Selenite
Among 4,693 on-market selenium products with an identifiable primary form, 17.3% use Selenium Amino Acid Chelate (811 products) and 11.3% use Sodium Selenite (528).
| Selenium Amino Acid Chelate | Sodium Selenite | |
|---|---|---|
| Quality tier | Unrated | Tier 2 |
| Selenium by weight | — | 45.7% |
| Share of market | 17.3% | 11.3% |
| On-market products | 811 | 528 |
| Median declared dose | 50 elemental mcg middle half: 20–100 | 50 elemental mcg middle half: 19.25–70 |
| Most common brands | Airborne, Ultima, Douglas Laboratories | Wonder Laboratories, DC, SmartyPants |
Doses are declared per serving in elemental mcg. “By weight” is the share of the ingredient that is the nutrient itself (e.g. elemental magnesium in a magnesium salt).
Why Selenium Amino Acid Chelate is unrated
Terminology inconsistent across manufacturers; needs manual review to determine actual composition.
Source: uncertain -- needs review
Why Sodium Selenite is tier 2
Well absorbed (~80%) but less well retained than organic selenomethionine per comparative bioavailability reviews.
Source: Fairweather-Tait SJ et al., selenium bioavailability review, Am J Clin Nutr -- specific comparative % vs selenate not independently re-verified
Tiers summarize published comparative bioavailability or outcome evidence for each form (see methodology).
This page describes the market; it is not a recommendation to take either form. Talk to a clinician about what's right for you.