Iron absorption from some Asian meals containing contamination iron.

Area of Science:

• Nutritional Science
• Biochemistry
• Public Health

Background:

• Accurate assessment of iron absorption is crucial for understanding iron bioavailability and nutritional status.
• Nonheme iron absorption from meals is influenced by various dietary factors.
• The extrinsic tag method is commonly used to measure iron absorption, but its validity can be affected by isotopic exchange.

Purpose of the Study:

• To investigate the extent of isotopic exchange between added radioiron tracers and native nonheme iron in Asian meals.
• To quantify the contribution of "contamination" iron to the total iron content of meals.
• To assess the implications of limited isotopic exchange and contamination iron on iron absorption measurements.

Main Methods:

• Analysis of 12 Asian meals using the extrinsic tag method for iron absorption measurement.
• Quantification of isotopic exchange using a recently developed in vitro method.
• Measurement of native iron and "contamination" iron within the meals.

Main Results:

• Up to 50% of nonheme iron in the analyzed Asian meals did not exchange with the added inorganic radioiron tracer.
• Significant amounts of "contamination" iron were identified, possessing limited bioavailability.
• The extent of isotopic exchange varied among the different meals studied.

Conclusions:

• Standard iron absorption measurements using extrinsic tracers may overestimate iron bioavailability due to incomplete isotopic exchange.
• The presence of contamination iron with low bioavailability is a critical factor to consider in iron absorption studies.
• These findings have significant implications for nutritional assessments, particularly in developing countries where iron deficiency is prevalent.