MitoGenix Guides
Selenium Supplements: What the Research Shows
Selenium is a trace mineral: the body needs very little of it, and too much is a problem. That makes it a good subject for plain reading. This guide covers what selenium does, what the research found in people (and in whom), and why the label dose and the upper limit matter.
What selenium does
Selenium is an essential trace element. The body builds it into around 25 selenoproteins, including glutathione peroxidase, one of its own antioxidant enzymes, and the enzymes that activate thyroid hormone. Reviews describe a role in the cellular response to oxidative stress, the immune response and thyroid hormone metabolism [3][4][5].
Our label is worded for exactly that: it supports normal selenoprotein activity and the body's natural antioxidant defences.
What the research found
| Study | Who and what | What it reported |
|---|---|---|
| Avery and Hoffmann, 2018 [3] | Review of selenium, selenoproteins and immune cell function. | The immune system relies on adequate selenium intake, which acts mostly through selenoproteins. |
| Huang et al., 2012 [4] | Review of selenium in inflammation and immunity, mostly cell and animal data. | Adequate selenium matters for immunity. Above-adequate levels can also affect immune cell function, so more is not simply better. |
| Steinbrenner et al., 2016 [5] | Review of antioxidant selenoenzymes. | Describes the antioxidant enzymes and their role in protection against oxidative damage. |
| Huwiler et al., 2024 [2] | Meta-analysis of 35 studies in people with Hashimoto thyroiditis. | Selenium lowered thyroid antibody levels and, in people not on thyroid medication, TSH. Certainty of evidence was moderate. Adverse effects were similar to control. |
| Kong et al., 2023 [6] | Meta-analysis of 7 trials, 342 people with Hashimoto thyroiditis. | No change in thyroid antibodies at 3 months, a significant fall after 6 months. |
| Fan et al., 2014 [7] | Meta-analysis of 9 studies, 787 people with autoimmune thyroiditis. | Antibody titres fell at 6 and 12 months. People also reported better mood or well-being. |
| Lippman et al., 2009 (SELECT) [8] | 35,533 relatively healthy men, 200 mcg selenium a day (as selenomethionine) or placebo, median follow-up about 5.5 years. | Selenium did not prevent prostate cancer or other cancers. A statistically non-significant increase in type 2 diabetes was seen in the selenium group. |
What this adds up to
- The thyroid research is in people with thyroid conditions, not in healthy shoppers. We don't claim our capsule helps a thyroid condition, and anyone with one should be under a doctor's care.
- The big cancer trial found no protective effect. Selenium is not a cancer-prevention supplement and shouldn't be taken as one.
- For healthy adults, the sound reason to care about selenium is meeting your normal need, not megadosing for an effect.
How the dose compares with the label
| Reference point | Selenium per day |
|---|---|
| Typical adult recommended intake (NIH) | 55 mcg |
| MitoGenix Selenium, one capsule | 200 mcg (364% of the NRV) |
| SELECT trial dose | 200 mcg |
| Upper limit for adults (NIH) | 400 mcg |
One capsule is well above the daily requirement but sits at half the upper limit, which is why the label says one capsule a day and not to exceed it. Selenium also comes from food, and some foods such as Brazil nuts are very high in it, so count your total.
How to use it sensibly
- One capsule a day, with food, early in the day. Do not exceed the recommended dose.
- Count other sources: other supplements and multivitamins, and selenium-rich foods.
- Too much selenium over time can cause hair and nail changes, stomach upset and a garlic-like breath odour. This is the reason there is an upper limit.
- Give it time. Selenium builds up gradually rather than overnight, so judge it over weeks, not days.
Who it's not for
Selenium is not intended for:
- anyone under 18
- pregnant or breastfeeding mothers (speak to a doctor or midwife about total intake)
If you have a thyroid condition, take medication or have a known medical condition, speak to a healthcare professional first. Stop use if you get any adverse reaction.
Frequently asked questions
How much selenium is in one capsule?
200 mcg of selenium per capsule, from a selenium amino-acid chelate at 2% elemental selenium, with 60 capsules per jar.
Can I take more than one capsule?
No. The full daily serving is one capsule, and the label says not to exceed it.
Does selenium help with thyroid problems?
The trials above were in people with Hashimoto's or autoimmune thyroiditis, and they measured antibody and hormone levels, not symptoms in healthy people. We don't make a claim about thyroid conditions, and they need medical care.
Does selenium prevent cancer?
The largest trial found no protective effect in relatively healthy men [8].
Which form of selenium is best?
Forms include selenomethionine, selenium yeast, sodium selenite and chelates. Studies differ in form and dose, so we state the form (an amino-acid chelate) and the elemental selenium delivered on the label.
Where to find it
MitoGenix Selenium is a single-ingredient capsule with the elemental dose declared, made in a GMP-certified facility in South Africa, independently tested, with no proprietary blends.
References
- National Institutes of Health, Office of Dietary Supplements. Selenium: fact sheet for health professionals. https://ods.od.nih.gov/factsheets/Selenium-HealthProfessional/
- Huwiler VV, Maissen-Abgottspon S, Stanga Z, et al. Selenium supplementation in patients with Hashimoto thyroiditis: a systematic review and meta-analysis of randomized clinical trials. 2024. https://pubmed.ncbi.nlm.nih.gov/38243784/
- Avery JC, Hoffmann PR. Selenium, selenoproteins, and immunity. 2018. https://pubmed.ncbi.nlm.nih.gov/30200430/
- Huang Z, Rose AH, Hoffmann PR. The role of selenium in inflammation and immunity: from molecular mechanisms to therapeutic opportunities. 2012. https://pubmed.ncbi.nlm.nih.gov/21955027/
- Steinbrenner H, Speckmann B, Klotz LO. Selenoproteins: antioxidant selenoenzymes and beyond. 2016. https://pubmed.ncbi.nlm.nih.gov/27095226/
- Kong XQ, Qiu GY, Yang ZB, Tan ZX, Quan XQ. Clinical efficacy of selenium supplementation in patients with Hashimoto thyroiditis: a systematic review and meta-analysis. 2023. https://pubmed.ncbi.nlm.nih.gov/37335715/
- Fan Y, Xu S, Zhang H, et al. Selenium supplementation for autoimmune thyroiditis: a systematic review and meta-analysis. 2014. https://pubmed.ncbi.nlm.nih.gov/25574167/
- Lippman SM, Klein EA, Goodman PJ, et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA, 2009. https://pubmed.ncbi.nlm.nih.gov/19066370/
This health supplement is not intended to diagnose, treat, cure or prevent any disease. This unregistered medicine has not been evaluated by SAHPRA for its quality, safety or intended use. Health supplements are intended only to complement your diet.
