Iron
Iron is a high-risk supplement with an RDA of 18 mg and a tolerable upper intake level (UL) of 45 mg per day according to NIH/NASEM standards. CNS lists a RDA of 20 mg and a UL of 42 mg; MHLW lists a RDA of 10.5 mg and a UL of 50 mg. It has 3 known interactions with other supplements including zinc, vitamin c, calcium. Regular monitoring is strongly recommended when adjusting your intake.
Quick take
Iron sits in the Trace Minerals category. This page consolidates 5 regional standards, and the limits vary enough that you should not treat one region's rule as universal.
It also has 3 known interactions, so the question is not just the label dose but whether the rest of your stack adds extra risk.
Taking multiple supplements? Check Iron for overlap
If Iron appears on two product labels, enter each daily amount and check the combined label total.
Check Iron across my supplementsFree. No account required.
Overdose Risk Warning
Acute iron overdose is dangerous; chronic excess can damage the liver, heart, and pancreas.
Regional Reference Values
| Region | Organization | RDA | Upper Limit (UL) | Unit |
|---|---|---|---|---|
| 🇺🇸 United States | FDA | 18 | 45 | mg |
| 🇪🇺 Europe | EFSA | 18 | 45 | mg |
| 🇦🇺 Australia | TGA | 18 | 45 | mg |
| 🇨🇳 China | 中国营养学会 | 20 | 42 | mg |
| 🇯🇵 Japan | MHLW | 10.5 | 50 | mg |
RDA = Recommended Daily Allowance (adequate intake for most adults). UL = Tolerable Upper Intake Level; some authorities have not established one.
Known Interactions
Vitamin C enhances iron absorption (positive interaction).
Taking together is beneficial.
Calcium may interfere with iron absorption when taken together.
Consider taking calcium and iron at different times of day, and ask a doctor or pharmacist for advice tailored to you.
How to use this page
First match your product label against the dose table above, then check whether the known interaction list includes anything in your current stack.
If you are taking multiple supplements, the safest approach is usually to audit the whole stack instead of judging a single bottle in isolation.
Frequently Asked Questions
How much Iron is too much?
FDA lists a formal upper limit (UL) of 45mg per day for Iron. Other regions may use a different value or have no established UL.
What is the recommended daily dose of Iron?
The RDA for Iron is 18mg per day for most adults. This amount is sufficient to meet the needs of 97-98% of healthy individuals.
Does Iron interact with other supplements?
Yes, Iron has 3 known interactions with other supplements. Iron and zinc compete for absorption.
Are you taking Iron?
Check if your supplement stack keeps Iron within safe limits.
Audit My SupplementsDisclaimer: NutriAudit is a decision-support tool designed to help you review your supplement stack for potential duplicate, conflicting, or excessive ingredients. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making changes to your supplement routine, especially if you are pregnant, nursing, taking medications, or have a medical condition.
Uses cited public reference data where the current dataset has a verified entry.