Can you take Vitamin C and Selenium together?
High-dose Vitamin C reduces sodium selenite to an unabsorbable form. Using selenomethionine instead avoids this entirely.
Severity
Caution
Evidence
moderate
Timing
Separate by 2+ hours, or use selenomethionine.
How it works
Ascorbic acid chemically reduces selenite to elemental selenium, which precipitates in the gut and cannot be absorbed.
The reaction is specific to inorganic selenium (sodium selenite). Selenomethionine, the organic form, is absorbed through a different pathway and is unaffected. If taking both, either separate them or choose the organic selenium form.
What to do
Separate by at least two hours, or switch to selenomethionine. Check your selenium supplement's form on the label.
Frequently asked
Should I separate Vitamin C and Selenium?
Consider separating them. Separate by 2+ hours, or use selenomethionine. Consult a healthcare professional for personalised advice.
Why do Vitamin C and Selenium interact?
Ascorbic acid chemically reduces selenite to elemental selenium, which precipitates in the gut and cannot be absorbed.
How strong is the evidence for this interaction?
The evidence is moderate. Some studies support this interaction, but more research may be needed.
About these supplements
Other Vitamin C interactions
Other Selenium interactions
Check your full stack
for interactions.
See what competes, what combines well, and when to take everything. Every interaction cites a published source.
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1 flagZinc and Iron compete for the same absorption pathway. Take at least 2 hours apart.
Supplements
This information is for educational purposes only. It is not medical advice and does not diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional.