A multivitamin, a hair supplement and an additional selenium capsule can all supply the same nutrient. Before adding another product, take stock of what you already use. Selenium is essential, but a higher intake is not automatically better. What matters is the specific reason for taking it, the actual amount and what your diet already contributes.
Three numbers answering three different questions
| Figure | Meaning |
|---|---|
| 60 µg for women, 70 µg for men | German Nutrition Society (DGE) estimates for adequate total daily intake. |
| 40 µg | BfR proposed maximum amount in the recommended daily serving of a food supplement. |
| 255 µg | EFSA tolerable upper level for total daily intake in adults, established in 2023. |
The first figures concern nutritional intake, the BfR proposal concerns a supplementary product, and the EFSA upper level concerns long-term total intake. None of these numbers is an instruction to supplement up to the upper level. The BfR value is a precautionary proposal, not a personal prescription. [1] [2] [3]
What selenium does in the body
Selenium is part of certain proteins involved in antioxidant systems and thyroid hormone metabolism. This explains its importance as a nutrient. It does not demonstrate that everyone with tiredness, hair problems or thyroid disease benefits from extra capsules. [4]
If you already have a treatment plan, ask whether supplementation was specifically recommended, for what purpose and with what follow-up. Buying another pack solely because of a general thyroid claim does not answer these questions.
Food sources and the particular case of Brazil nuts
Fish, meat and eggs contribute to intake. Selenium levels in plants depend strongly on the growing area and soil, so figures from overseas food tables should not be transferred without checking. Brazil nuts can contain substantial selenium, but variable levels make them unsuitable as precisely dosed daily tablets. The DGE also highlights their potential radium content. [4]
With a predominantly plant-based diet, review your overall food selection systematically. Do not replace the question of adequate intake with a fixed number of nuts. A food diary can show which foods appear regularly; it cannot measure your individual selenium status.
How to identify overlapping intake
A clearly hypothetical example: a multivitamin provides 40 µg, a hair product 55 µg and a separate capsule 100 µg. Together, that is 195 µg from supplements alone, with food still to be added. Each product having an understandable daily serving does not automatically make the combination sensible.
For each product, record selenium per capsule, capsules per day and any additional days of use. Check the unit: 1 mg equals 1,000 µg. When switching brands, recheck the amount rather than automatically keeping the previous number of capsules.
Which selenium form is best?
Selenomethionine, selenium-enriched yeast and sodium selenite are different sources. Both organic and inorganic forms can cause harm with persistently excessive intake. The word organic therefore does not replace a needs and quantity check. [3]
First compare a daily serving appropriate to the agreed purpose. Then consider ingredients, clear labelling and price. A more expensive form alone does not establish a better product for hair, immunity or thyroid function.
When medical advice matters
Hair loss and brittle nails can also occur with excessive selenium intake. Other possible signs include a metallic taste, garlic-like breath and digestive symptoms. These symptoms are not conclusive, but they warrant timely assessment if you are supplementing. Do not increase the amount yourself; if symptoms occur, stop a non-prescribed selenium supplement for now and seek professional advice. [3]
Frequently asked questions
Is 255 µg a recommended daily dose?
No. It is an upper level for total intake, not a target.
Is a claim about thyroid support enough reason to buy?
No. A nutrient's function does not replace an individual decision about supplementation.
Can I dose selenium using a fixed number of Brazil nuts?
Not reliably. Their content varies.
Does selenium in a multivitamin count?
Yes. Include every supplement and the rest of your diet in the overview.
Conclusion
A useful selenium comparison starts with the reason for use and a complete list of amounts. Several small additions can together create an unnecessarily high intake. A clear decision is more helpful than another capsule taken just in case.
Read more: Planning nutrients on a vegan diet and Understanding B-complex supplements.
Sources
- DGE: Selenium reference values (German)
- BfR: Proposed maximum amounts, selenium on page 11 (German)
- NIH ODS: Selenium, including the EFSA upper level from 2023
- DGE: Questions and answers about selenium (German)
Editorially revised: 26 September 2026. General information for adults, not individual diagnosis or treatment. Reference values are from Germany or EFSA. Natur Total also operates a food supplement shop.
