Effects of Vitamin A and Carotenoids on Iron Absorption

Effects of Vitamin A and Carotenoids on Iron Absorption

The objective of this study is to investigate the effect of vitamin A and carotenoids on iron absorption in healthy subjects with low and normal vitamin A status. Vitamin A and carotenoids have been reported to enhance the nonheme iron absorption, but the results from human isotope studies are equivocal. Radio-iron studies in Venezuelan adults have consistently reported an increase in iron absorption, whereas stable and radio isotopes studies conducted in Sweden and Switzerland reported no influence. Differences in vitamin A status of the subjects may be a possible explanation for the contradictory findings. In this study, iron absorption will be measured from an iron-fortified maize bread meal with or without retinyl palmitate or β-carotene by using both stable- and radioactive-isotope techniques in Venezuelan women with a range of vitamin A status.

Inclusion Criteria:

• Women 18-52 years old
• Body weight ≤ 70 kg
• Body mass index (BMI), 18.5-30 kg/m2
• Adequate vitamin A status (SR ≥ 0.7 μmol/L, n=20)
• Inadequate vitamin A status (SR < 0.7 μmol/L, n=20)
• No major medical illnesses (no known infection, gastrointestinal or metabolic disorders)

Exclusion Criteria:

• Pregnancy or lactation
• Regular intake of medication (except oral contraceptives)
• Blood donation or significant blood loss (accident, surgery) over the past 4 months
• Currently participating in another clinical trial or having participated in another clinical trial during the last 3 months prior to the beginning of this study
• Former participation in a study involving administration of iron stable isotopes