Mineral
Selenium
Selenium supports thyroid hormone conversion and shows modest benefits for thyroid antibodies and mood in people with existing autoimmune thyroid conditions like Hashimoto's thyroiditis. Most Americans get adequate selenium from food, particularly those eating Brazil nuts or seafood regularly. Supplementation is most helpful when you have confirmed selenium deficiency or diagnosed thyroid autoimmunity, making testing a smart first step.
30-second summary
Selenium supports thyroid hormone conversion and shows modest benefits for thyroid antibodies and mood in people with existing autoimmune thyroid conditions like Hashimoto's thyroiditis. Most Americans get adequate selenium from food, particularly those eating Brazil nuts or seafood regularly. Supplementation is most helpful when you have confirmed selenium deficiency or diagnosed thyroid autoimmunity, making testing a smart first step.
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Overall: Mixed evidence
Randomised controlled trials
Several small trials show selenium reduces thyroid antibodies in Hashimoto's patients, but studies in healthy adults show minimal benefits.
Population studies consistently link adequate selenium status with better thyroid function and lower autoimmune thyroid disease rates.
Meta-analyses confirm selenium supplementation reduces thyroid peroxidase antibodies in people with autoimmune thyroid disease.
Menopause-specific trials
No randomized trials have specifically studied selenium supplementation in menopausal women for menopause-related symptoms.
What we do not know
We lack studies specifically in menopausal women with normal thyroid function. The optimal dose for thyroid support hasn't been established through dose-response studies. Most selenium research focuses on people with existing thyroid disease rather than healthy adults. We don't know if selenium prevents thyroid problems from developing during menopause. Long-term safety data beyond 12 months is limited for doses above 200mcg daily.
How it is used
Common dose range
100-200mcg daily
Notes on dosing
Do not exceed 400mcg daily. Selenomethionine is the best-absorbed form.
Get it from food first
Food sources are better absorbed than most supplements and come with co-factors that support the same pathways. If you eat two or three of these consistently, you may not need a supplement at all.
Brazil nuts
1-2 nuts
highest food source, provides 70-90mcg per nut
Yellowfin tuna
3 oz
92mcg, also provides protein and omega-3s
Halibut
3 oz
40mcg, excellent protein source
Sardines
3 oz
45mcg, also rich in calcium and vitamin D
Sunflower seeds
1 oz
19mcg, good plant-based option
Eggs
1 large
15mcg, from pasture-raised chickens
Mediterranean diet
rich in seafood and nuts provides consistent selenium intake
Pescatarian eating
emphasizes fish and shellfish which are excellent selenium sources
What depletes Selenium
Alcohol consumption increases selenium excretion. High mercury exposure can interfere with selenium utilization. Chronic digestive issues like Crohn's disease or celiac disease reduce selenium absorption. Smoking increases oxidative stress and selenium needs.
Interactions and cautions
No significant interactions noted at recommended doses.
Rose bottom line
"If you're dealing with thyroid issues during menopause, selenium deserves a conversation with your doctor - the evidence is genuinely promising for autoimmune thyroid conditions. For most women, a couple Brazil nuts daily or regular seafood provides all the selenium your body needs. You don't have to figure this out alone."