Iron

What it is · too little · too much · daily reference values by country

For reference only. This is not a diagnosis or a prescription. If you have concerns, talk to a doctor or pharmacist.

What it is

Iron is a component of hemoglobin and myoglobin, and it carries and stores oxygen. (Korea Ministry of Health and Welfare · Korean Nutrition Society)
Iron is required for oxygen transport, electron transfer, oxidase activities and energy metabolism. (European Food Safety Authority)
Iron is a mineral that the body needs for growth and development. Your body uses iron to make hemoglobin, a protein in red blood cells that carries oxygen from the lungs to all parts of the body, and myoglobin, a protein that provides oxygen to muscles. (US National Institutes of Health)
Wording taken from the NIH ODS fact sheet by SuppleBoard, with some details left out.

Getting too little

Too little iron can cause anemia, and it is linked to lower work performance and lower cognitive function, among other things. (Korea Ministry of Health and Welfare · Korean Nutrition Society)
Iron deficiency is associated with reduced physical work capacity, delayed psychomotor development in infants, impaired cognitive function, and adverse effects for both the mother and the fetus. (European Food Safety Authority)
In the short term, getting too little iron does not cause obvious symptoms. However, when levels of iron stored in the body become low, iron deficiency anemia sets in. (US National Institutes of Health)
Wording taken from the NIH ODS fact sheet by SuppleBoard, with some details left out.
Symptoms of iron deficiency anemia include GI upset, weakness, tiredness, lack of energy, and problems with concentration and memory. (US National Institutes of Health)
Wording taken from the NIH ODS fact sheet by SuppleBoard, with some details left out.

Getting too much

Getting a large amount of iron from supplements can cause stomach and bowel symptoms such as constipation, diarrhea, abdominal pain, nausea, and vomiting. It may also lower the absorption of other trace elements such as zinc. (Korea Ministry of Health and Welfare · Korean Nutrition Society)
In adults with normal gut function, the chance of too much iron building up in the body from an ordinary diet alone is said to be very low. (Korea Ministry of Health and Welfare · Korean Nutrition Society)
In healthy people, taking high doses of iron supplements (especially on an empty stomach) can cause an upset stomach, constipation, nausea, abdominal pain, vomiting, and diarrhea. (US National Institutes of Health)
Wording taken from the NIH ODS fact sheet by SuppleBoard, with some details left out.
Extremely high doses of iron can cause organ failure, coma, convulsions, and death. (US National Institutes of Health)
Wording taken from the NIH ODS fact sheet by SuppleBoard, with some details left out.

Daily reference values by country

Korea · US · EU — tap to open

These tables are daily reference values for healthy people. Numbers in the text above are a different kind of value, and you cannot diagnose yourself from them. How to read RDA, AI and UL

Korea — 2025 Dietary Reference Intakes for Koreans (Ministry of Health and Welfare)

Group	EAR	RNI	AI	UL
6–11 months	4 mg	6 mg		40 mg
0–5 months			0.3 mg	40 mg
1–2 years	4 mg	6 mg		40 mg
3–5 years	4 mg	6 mg		40 mg
Male · 6–8 years	5 mg	7 mg		40 mg
Male · 9–11 years	6 mg	8 mg		40 mg
Male · 12–14 years	8 mg	11 mg		40 mg
Male · 15–18 years	8 mg	11 mg		45 mg
Male · 19–29 years	6 mg	8 mg		45 mg
Male · 30–49 years	6 mg	8 mg		45 mg
Male · 50–64 years	6 mg	8 mg		45 mg
Male · 65–74 years	6 mg	8 mg		45 mg
Male · 75+ years	5 mg	7 mg		45 mg
Female · 6–8 years	5 mg	7 mg		40 mg
Female · 9–11 years	6 mg	8 mg		40 mg
Female · 12–14 years	8 mg	13 mg		40 mg
Female · 15–18 years	7 mg	12 mg		45 mg
Female · 19–29 years	7 mg	12 mg		45 mg
Female · 30–49 years	7 mg	12 mg		45 mg
Female · 50–64 years	5 mg	7 mg		45 mg
Female · 65–74 years	4 mg	6 mg		45 mg
Female · 75+ years	4 mg	6 mg		45 mg
Pregnancy	+8 mg	+9 mg		45 mg
Lactation	+0 mg	+0 mg		45 mg

UL — applies to: Total iron intake.

US — NASEM (National Academies)

Group	EAR	RDA	AI	UL
7–12 months	6.9 mg	11 mg		40 mg
1–3 years	3 mg	7 mg		40 mg
4–8 years	4.1 mg	10 mg		40 mg
Male · 9–13 years	5.9 mg	8 mg		40 mg
Male · 14–18 years	7.7 mg	11 mg		45 mg
Male · 19–30 years	6 mg	8 mg		45 mg
Male · 31–50 years	6 mg	8 mg		45 mg
Male · 51–70 years	6 mg	8 mg		45 mg
Male · 71+ years	6 mg	8 mg		45 mg
Female · 9–13 years	5.7 mg	8 mg		40 mg
Female · 14–18 years	7.9 mg	15 mg		45 mg
Female · 19–30 years	8.1 mg	18 mg		45 mg
Female · 31–50 years	8.1 mg	18 mg		45 mg
Female · 51–70 years	5 mg	8 mg		45 mg
Female · 71+ years	5 mg	8 mg		45 mg
Pregnancy · 14–18 years	23 mg	27 mg		45 mg
Pregnancy · 19–30 years	22 mg	27 mg		45 mg
Pregnancy · 31–50 years	22 mg	27 mg		45 mg
Lactation · 14–18 years	7 mg	10 mg		45 mg
Lactation · 19–30 years	6.5 mg	9 mg		45 mg
Lactation · 31–50 years	6.5 mg	9 mg		45 mg
0–6 months			0.27 mg	40 mg

UL — applies to: Unless otherwise specified, the UL represents total intake from food, water, and supplements.

EU — EFSA (European Food Safety Authority)

Group	AR	PRI	UL	Safe level of intake
7–11 months	8 mg	11 mg
1–6 years	5 mg	7 mg
7–11 years	8 mg	11 mg
Male · 12–17 years	8 mg	11 mg
Female · 12–17 years	7 mg	13 mg
Female · 18–59 years	7 mg	16 mg
Female · 40+ years	6 mg	11 mg
Male · 18+ years	6 mg	11 mg
Pregnancy · 18–60 years	7 mg	16 mg
Lactation · 18–60 years	7 mg	16 mg
18+ years			—	Checking
Pregnancy · 18+ years			—	Checking
Lactation · 18+ years			—	Checking
1–3 years				Checking
4–6 years				Checking
7–10 years				Checking
11–14 years				Checking
15–17 years				Checking

Sources

EFSA DRV Finder (Dietary Reference Values) · checked 2026-10-07
EFSA DRV Finder — nutrient descriptions · checked 2026-10-07
EFSA Overview on Tolerable Upper Intake Levels (v11, August 2025) · checked 2026-10-07
2025 Dietary Reference Intakes for Koreans, Vol. 3: Minerals (Korean Ministry of Health and Welfare · The Korean Nutrition Society; in Korean) · checked 2026-10-07
2025 Dietary Reference Intakes for Koreans — summary tables (Korean Ministry of Health and Welfare · The Korean Nutrition Society; in Korean) · checked 2026-10-07
NASEM Dietary Reference Intakes summary tables (Appendix J, 2019) · checked 2026-10-07
NIH Office of Dietary Supplements — Iron Fact Sheet for Consumers · checked 2026-10-13

The sentences are plain-language summaries of official sources written by SuppleBoard. Each English sentence was checked against the source text by an AI reviewer before publishing. The agencies do not endorse this site. Published 2026-10-16.

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