L-Selenomethionine vs. Sodium Selenite
Among 4,693 on-market selenium products with an identifiable primary form, 57.5% use L-Selenomethionine (2,697 products) and 11.3% use Sodium Selenite (528).
| L-Selenomethionine | Sodium Selenite | |
|---|---|---|
| Quality tier | Tier 1 | Tier 2 |
| Selenium by weight | 40.3% | 45.7% |
| Share of market | 57.5% | 11.3% |
| On-market products | 2,697 | 528 |
| Median declared dose | 70 elemental mcg middle half: 35–105 | 50 elemental mcg middle half: 19.25–70 |
| Most common brands | Pure Encapsulations, GNC Mega Men, Carlson | 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 L-Selenomethionine is tier 1
Retained longer than inorganic selenite/selenate (organic forms show higher retention; Fairweather-Tait 2010); the form used in SELECT. The NPC trial is reported to have used selenium-enriched yeast (not confirmed from the abstract).
Source: Fairweather-Tait SJ et al. 2010, Am J Clin Nutr 91(5):1484S-1491S, PMID 20200264; Lippman SM et al. 2009, JAMA 301(1):39-51, PMID 19066370; Clark LC et al. 1996, JAMA 276(24):1957-1963, PMID 8971064
Why Sodium Selenite is tier 2
Well absorbed but less well retained than organic selenomethionine (organic forms show higher retention than inorganic forms; Fairweather-Tait 2010).
Source: Fairweather-Tait SJ, Collings R, Hurst R. 2010, Am J Clin Nutr 91(5):1484S-1491S, PMID 20200264