Se2+.
Research-backed compound with potential health benefits. Supports your thyroid, acts as a powerful antioxidant, and helps your immune system. Think of it as a key manager for several important systems.
Reviewed March 2026
- Category
- Compound
What Se2+ is, and what it does.
- Does it work
- Maybe. It's essential, but most people get enough from food. For everyone else, probably not necessary.
- How much to take
- 55-200 mcg daily. The upper safe limit is 400 mcg from all sources, including food. Don't eyeball this one.
- Time to feel it
- Plasma selenium and glutathione peroxidase activity rise over roughly three to six months. It's a blood panel readout rather than a sensation.
- The first dose
- Nothing. This is a mineral, not a medication. It needs time to integrate into your body's systems.
- With regular use
- If you were deficient, you might see improvements in thyroid labs or feel more resilient over 2-3 months. If you weren't, you'll feel no different.
- How well tolerated
- Well tolerated at recommended doses. The line between enough and too much is thin. Don't go over 400 mcg/day total. Selenosis (toxicity) is a real thing.
- How it feels
- You don't feel it. Its job is to keep background processes running smoothly. The main 'feeling' is the absence of deficiency symptoms.
- The overlooked benefit
- Selenomethionine slots into body protein anywhere methionine would go, so it builds a slow-turnover store that keeps releasing selenium for months.
50 to 100mcg a day is where Se2+ works.
Source: Proprietary selenium compound. Doses aligned with general selenium RDA (55mcg) and UL (400mcg).
The proof, claim by claim.
These words describe the research, not the molecule's worth. Research strength is how much work stands behind one claim, and it is never a product score.
Se2+ is documented in the library; the clinical read is in the queue. Nothing about the strength of the research prints until the read is done.
- Normal thyroid hormone metabolismNarrative review
- Glutathione peroxidase and thioredoxin reductase activityRandomised trial
- Normal immune functionRandomised trial
- Sperm motility and male fertility supportRandomised trial
Questions people ask about Se2+.
- Do I actually need to take this?
- Probably not. Most diets in North America provide enough. Get tested or talk to a doctor if you suspect a deficiency.
- Can I just eat Brazil nuts instead?
- You can, but it's tricky. One Brazil nut can have 60-90 mcg, but some have way more. The dose is inconsistent. A supplement is more precise.
- What are the signs of taking too much?
- Garlic breath, a metallic taste, hair loss, and brittle nails are the classic signs. Stop taking it if you notice these.
- Can I take it with my multivitamin?
- Check the labels first. Many multivitamins already contain selenium. Add up all sources to make sure you're under the 400 mcg/day limit.
Why these belong in the same formula. Each row says what the basis is, from settled biochemistry through to a trial that measured the pair.
Selenomethionine, the organic selenium form this entry describes, is absorbed by the same sodium-dependent neutral amino acid transporters that carry methionine, and it is then incorporated non-specifically into body protein wherever methionine would go. High dietary methionine competes for both the transporter and the incorporation step. That is why selenomethionine builds a tissue reserve while inorganic forms do not.
Selenomethionine must be converted through the transsulfuration route to selenocysteine before its selenium can enter the regulated selenoprotein pool. Cysteine and methionine status shape the flux through that route. Without the conversion, selenium held in body protein is a store rather than an active pool.
Cystathionine beta-synthase and cystathionine gamma-lyase, the transsulfuration enzymes that carry selenomethionine toward selenocysteine, are pyridoxal-5-phosphate dependent. Selenocysteine beta-lyase, which releases selenide for reuse, is also a PLP enzyme. Vitamin B6 status therefore sits directly on the path that turns dietary organic selenium into usable selenium.
Selenocysteine is not charged onto its tRNA directly. Serine is loaded first, then converted to selenocysteine on the tRNA using selenophosphate. Serine is therefore the carbon skeleton of every selenocysteine residue in every selenoprotein.
Glutathione peroxidases are selenoenzymes that reduce lipid hydroperoxides after they have formed, while tocopherol intercepts the chain-propagating radical in the membrane before they form. The two work at different points of the same lipid peroxidation sequence, which is the long-standing basis for pairing them. This is a mechanistic complementarity, not a claim about any measured clinical outcome.
Glutathione peroxidase uses reduced glutathione as its electron donor, oxidising two molecules of it for every hydroperoxide reduced. Selenium supplies the catalytic selenocysteine and glutathione supplies the reducing equivalents. Neither part of the couple functions without the other.
N-acetylcysteine supplies cysteine, the rate-limiting substrate for glutathione synthesis. Since selenium-dependent glutathione peroxidase consumes glutathione as it works, cysteine availability sets the ceiling on that cycle. The relationship is a substrate supply chain rather than a direct interaction with selenium.
The three iodothyronine deiodinases are selenoenzymes, so selenium is required for the normal conversion of thyroid hormone between its forms. Iodine supplies the substrate and selenium supplies the catalytic machinery that acts on it. Both nutrients are needed for normal thyroid hormone handling.
Ascorbate reduces inorganic selenite chemically, which is a well-described interaction for that form. Selenomethionine has no equivalent redox-sensitive centre in the gut, so the same concern does not apply to the organic form. The distinction matters when a multivitamin declares selenium without naming the source compound.
Zinc supports the copper-zinc superoxide dismutase step that converts superoxide to hydrogen peroxide, and selenium-dependent glutathione peroxidase is one of the enzymes that then removes that peroxide. The two nutrients sit consecutively on the same detoxification chain. Read it as sequential rather than as one boosting the other.
Thioredoxin reductase, a selenoenzyme, can reduce ubiquinone back to its ubiquinol form, linking selenium status to the recycling of the coenzyme Q pool. This gives a chemical basis for combining the two in a formula. It is a mechanistic link measured in enzymatic systems, not a clinical outcome.
Dihydrolipoic acid and the selenium-dependent thioredoxin system both operate as thiol-based reducing couples inside the cell. They overlap in regenerating oxidised protein thiols. The overlap is chemical and has not been measured as a co-supplementation result.
This entry describes an oxidation state of the same element covered by the general selenium page, most often supplied as selenomethionine or selenium yeast. Stacking a named selenium form on top of a general selenium ingredient adds the two intakes together against the same requirement. Total intake from all sources is what counts, not the number of entries on a label.
Nothing specific on file for Se2+. Match the label to the daily amount above, and tell your doctor what you take.
Not medical advice. Show the label to your pharmacist.What Se2+ actually does.
The body uses selenium by building it into a special amino acid, which cells slot into proteins using a dedicated genetic instruction.
Selenium is not attached to a finished amino acid; it is built onto a serine while that serine sits on its carrier molecule.
Selenium from food and yeast gets built into ordinary proteins by mistake, which gives the body a slow-release store.
Selenium is a working part of about twenty-five human proteins, most of them involved in handling oxidation or thyroid hormone.
Where Se2+ comes from.
Selenium is recovered as a mineral salt from copper refining, then either fed to yeast that build it into their own amino acids, or converted chemically into selenomethionine. Either way the finished material is tested for how much selenium it holds and in what chemical form.
The same molecule is reached more than one way. Which route a given product used is a manufacturing choice, and the finished compound is the same either way.
Production starts from a purified inorganic selenium salt, itself recovered from the anode slimes of copper electrolytic refining. Selenium is not mined for its own sake.
Saccharomyces cerevisiae is grown on a medium dosed with inorganic selenium. The yeast takes the selenium up through its sulfate assimilation route and builds it into amino acids, mainly selenomethionine, in place of sulfur.
L-selenomethionine can instead be made synthetically or by enzymatic resolution, giving a single defined compound rather than a biomass. The two routes give different products: one is a defined molecule, the other a food-derived matrix of selenium species.
For the yeast route the biomass is harvested and washed to remove unincorporated inorganic selenium, which is the step that determines how much of the declared selenium is actually organic.
Yeast is heat-inactivated and spray dried. Synthetic selenomethionine is crystallised and dried to a defined purity.
Batches are assayed for total selenium by ICP-MS and, for yeast, for the selenomethionine fraction and residual inorganic selenium.
Because the amounts used are in micrograms, the concentrate is triturated with a carrier to make an evenly blendable premix.
Which of the two routes a given finished product used is often not stated on a label, and the two give different mixes of selenium compounds.
Getting Se2+ from food.
The whole-food sources on file. A supplement closes the gap, it does not replace dinner.
A gram-for-gram figure (how much of each you would eat to match a dose) will appear here once it is sourced and reviewed. This page will not print a number it cannot cite.
The forms it comes in.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This information is for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Consult your healthcare provider before starting any supplement regimen.