Selenomethionine
Selenomethionine suppliers and sourcing guide
Selenomethionine is an amino acid in which selenium takes the place of the sulfur atom in methionine. For supplements it is either made by chemical synthesis as L-selenomethionine (or as the DL- form) or delivered within selenium-enriched yeast, where it is the main selenium compound. Pure L-selenomethionine is about 40% selenium, so brands usually buy it as a dilute trituration on a carrier for tablets, capsules and premixes.
- Category
- Vitamins and minerals
- Also known as
- L-selenomethionine · SeMet · Seleno-L-methionine
- Facts checked
- November 2026
Forms and grades of selenomethionine
Suppliers sell different products under the same name. Specify the one you need.
L-selenomethionine triturations
Synthetic L-selenomethionine diluted to a stated selenium level on dicalcium phosphate, microcrystalline cellulose or maltodextrin.
Pure L-selenomethionine
Concentrated crystalline material for premix makers.
DL-selenomethionine
Racemic form, cheaper to make; the isomer should be stated on the specification.
Yeast-bound selenomethionine
Selenomethionine supplied within selenium yeast rather than as an isolated compound.
What to check on the COA
Compare each result with your own specification when the lot arrives.
- Selenium assay
- Total selenium by ICP-MS or ICP-OES, per gram of trituration.
- Selenomethionine assay
- Selenomethionine by HPLC or HPLC-ICP-MS, which confirms the selenium is present as the stated compound.
- Optical purity
- Specific rotation or chiral HPLC to confirm the L-form when L-selenomethionine is specified.
- Inorganic selenium
- Selenite and selenate by speciation methods, where the specification sets a limit.
- Heavy metals and microbiology
- Lead, arsenic, cadmium and mercury by ICP-MS, plus total plate count, yeast and mold.
Storage, lots and expiry
Storage and shelf life
Keep selenomethionine and its triturations in tightly closed, light-resistant containers in a cool, dry, secured area; the compound can oxidize over time. Follow the supplier's safety data sheet for handling the concentrated form. Shelf life is set by the supplier's specification, with selenium and selenomethionine retested on aged stock.
Lots and expiry dates
Record total selenium, selenomethionine and isomer for each lot, and check dilution strength before batching. Keep concentrated and diluted grades on separate item codes.
Regulatory status
Facts from regulators and standards bodies, each linked to its source.
Health Canada's Multi-Vitamin/Mineral Supplements monograph for natural health products lists selenomethionine among the source ingredients for selenium (Table 2).
Source: webprod.hc-sc.gc.ca (opens in a new tab)21 CFR 101.9(c)(8)(iv) sets the Reference Daily Intake for selenium at 55 mcg for adults and children 4 years and older.
Source: ecfr.gov (opens in a new tab)
This is general information, not regulatory advice. Status differs by country and by how the ingredient is used, so check the rules for your product and market.
Selenomethionine suppliers
Manufacturers and distributors whose own websites say they sell it.
We are checking selenomethionine suppliers now
Every listing is checked against the supplier’s own website before it goes live, so this list fills in over the coming weeks. The specs and COA checklist above are ready today.
Sell selenomethionine? Request a listingFrequently asked questions
What forms of selenomethionine can brands buy?
Common forms include l-selenomethionine triturations, pure L-selenomethionine, dL-selenomethionine and yeast-bound selenomethionine. Ask each supplier for the specification sheet of the exact grade they quote.
What should the COA for selenomethionine include?
Expect selenium assay, selenomethionine assay, optical purity, inorganic selenium and heavy metals and microbiology, each with its method, specification and result for that lot.
How should selenomethionine be stored?
Keep selenomethionine and its triturations in tightly closed, light-resistant containers in a cool, dry, secured area; the compound can oxidize over time. Follow the supplier's safety data sheet for handling the concentrated form. Shelf life is set by the supplier's specification, with selenium and selenomethionine retested on aged stock.
What is the regulatory status of selenomethionine?
Health Canada's Multi-Vitamin/Mineral Supplements monograph for natural health products lists selenomethionine among the source ingredients for selenium (Table 2). 21 CFR 101.9(c)(8)(iv) sets the Reference Daily Intake for selenium at 55 mcg for adults and children 4 years and older.
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