Scientific opinion on the tolerable upper intake level for iron

Area of Science:

• Nutrition science
• Dietary guidelines
• Public health

Background:

• Systemic iron overload can cause organ toxicity.
• Previous research has not established a tolerable upper intake level (UL) for iron.
• The European Commission requested an opinion on safe iron intake levels.

Purpose of the Study:

• To establish a scientific opinion on the tolerable upper intake level (UL) for iron.
• To review evidence on high iron intake risks, including chronic diseases and gastrointestinal effects.
• To assess adverse effects of iron supplementation in infants, children, and pregnant women.

Main Methods:

• Conducted systematic reviews to identify relevant scientific evidence.
• Utilized dose-response analysis, identifying black stools as a key indicator.
• Applied allometric scaling (body weight^0.75) to extrapolate safe intake levels across age groups.

Main Results:

• No tolerable upper intake level (UL) for iron could be established.
• A safe iron intake level of 40 mg/day was determined for adults.
• Safe intake levels for children and adolescents ranged from 10 mg/day (1-3 years) to 35 mg/day (15-17 years).
• A safe supplemental iron intake of 5 mg/day was derived for infants (4-11 months).

Conclusions:

• Safe iron intake levels have been established for various age groups.
• The established safe levels are derived from conservative endpoints like black stools.
• These safe intake levels apply to iron from fortified foods and supplements, excluding infant formulas.