Selenium
Last updated: August 9, 2026
Benefits
A trace mineral that acts as an antioxidant and supports thyroid hormone metabolism and immune function.
How much you need
Recommended daily amounts by life stage, per NIH and NASEM Dietary Reference Intakes. Where the evidence hasn't been enough to set a full RDA (Recommended Dietary Allowance), NASEM sets an AI (Adequate Intake) instead — both are shown together below.
| Life stage | RDA / AI |
|---|---|
| Children 1–3 | 20 mcg |
| Children 4–8 | 30 mcg |
| Boys 9–13 | 40 mcg |
| Girls 9–13 | 40 mcg |
| Males 14–18 | 55 mcg |
| Females 14–18 | 55 mcg |
| Men 19–50 | 55 mcg |
| Women 19–50 | 55 mcg |
| Men 51–70 | 55 mcg |
| Women 51–70 | 55 mcg |
| Men 71+ | 55 mcg |
| Women 71+ | 55 mcg |
| Pregnancy 14–18 | 60 mcg |
| Pregnancy 19–50 | 60 mcg |
| Lactation 14–18 | 70 mcg |
| Lactation 19–50 | 70 mcg |
Upper limit
This limit applies to total Selenium intake — food and supplements combined.
| Life stage | Tolerable upper limit |
|---|---|
| Children 1–3 | 90 mcg |
| Children 4–8 | 150 mcg |
| Boys 9–13 | 280 mcg |
| Girls 9–13 | 280 mcg |
| Males 14–18 | 400 mcg |
| Females 14–18 | 400 mcg |
| Men 19–50 | 400 mcg |
| Women 19–50 | 400 mcg |
| Men 51–70 | 400 mcg |
| Women 51–70 | 400 mcg |
| Men 71+ | 400 mcg |
| Women 71+ | 400 mcg |
| Pregnancy 14–18 | 400 mcg |
| Pregnancy 19–50 | 400 mcg |
| Lactation 14–18 | 400 mcg |
| Lactation 19–50 | 400 mcg |
Sustained excess selenium can cause hair and nail loss or brittleness, nausea, fatigue, and irritability.
Best food sources
| Serving | ||
|---|---|---|
| Brazil nuts | — | — |
| Tuna and sardines | — | — |
| Shrimp | — | — |
| Eggs | — | — |
| Brown rice | — | — |
Absorption & caution
Caution: Selenium is needed only in tiny amounts, and the gap between enough and too much is small. Brazil nuts are the extreme case: one nut can carry more than a full day's requirement, and a small handful can pass the adult upper limit on its own. The amount varies widely from nut to nut, so they are better treated as an occasional food than a daily one — and for a young child the limit is far lower still, low enough that a single nut can reach it. Add selenium supplements cautiously, especially if Brazil nuts are already part of your week.
Pairings
Works well with
- Iodine — Selenium supports the enzymes that let the thyroid put iodine to work.
Body systems & goals
Body systems it supports
- Thyroid — Your thyroid sets the pace for your whole metabolism, and it needs these nutrients to make its hormones. Supporting them helps your body maintain steady energy and temperature. (established evidence)
- Immune System — Your immune system is on quiet watch every day, and these nutrients supply the raw materials its defenses run on. Keeping them steady supports your body's resilience, which matters most when you're already run down. (established evidence)
Goals it supports
- Cellular health (established evidence)
Frequently asked questions
How much Selenium do adult women need per day?
Adult women (19–50) need 55 mcg of Selenium per day, per NIH/NASEM Dietary Reference Intakes.
How much Selenium do adult men need per day?
Adult men (19–50) need 55 mcg of Selenium per day, per NIH/NASEM Dietary Reference Intakes.
Does pregnancy change how much Selenium you need?
Yes — during pregnancy (ages 19–50) the recommended amount rises to 60 mcg per day, compared with 55 mcg for non-pregnant adult women.
Is there an upper limit for Selenium?
Yes — for adults 19–50, the tolerable upper limit is 400 mcg. Sustained excess selenium can cause hair and nail loss or brittleness, nausea, fatigue, and irritability.
What foods are highest in Selenium?
Good sources include Brazil nuts, Tuna and sardines, Shrimp, Eggs, and Brown rice.
How Tavita handles this
Tavita logs Selenium from both the food you eat and the supplements you take, adding both into one running daily total. It warns you before you reach the tolerable upper limit, counting your combined intake from food and supplements.
Sources
Figures on this page come from the NIH Office of Dietary Supplements fact sheets and the National Academies of Sciences, Engineering, and Medicine (NASEM) Dietary Reference Intake tables — the same dataset that powers the Tavita app. They were independently re-verified by blind re-derivation on August 9, 2026. See the methodology page for how this library is built and kept current.
Tavita is not a medical provider. This page is educational information, not medical advice — talk to your clinician before changing your supplement or medication routine.