Objective: To investigate the effect of vitamin A (VA) supplementation on the nutritional status of iron in healthy adults.
Methods: One hundred and fifteen healthy adults were recruited and divided randomly into four groups, with 28 or 29 adults in each group. VA supplements with different doses of retinyl acetate in capsules were given for 4-month. The equivalent doses of supplemented retinyl acetate were 600 microg/d, 400 microg/d, 200 microg/d and 0 microg/d (control) of retinol, respectively. The capsules were administered orally by double blind method. During the experiment, the subjects kept their usual dietary pattern but avoided high VA or pre-VA carotenoids foods from their diets. A 24-h dietary recall was carried out monthly on every subject. Before and after the intervention, the fast blood samples were collected from each subject, and were determined for hemoglobin concentration, levels of serum retinol, iron, ferrtin and transferrtin receptor.
Results: Total 108 subjects finished the experiment, with 27, 28, 27 and 26 persons left in group A, B, C and D, respectively. The subjects from each group had similar dietary intakes of energy nutrients, VA and iron (both were P > 0.05) during the experimental period. The serum retinol concentration of subjects from group A increased from 1.63 +/- 0.55 micromol/L of baseline to 1.93 +/-0.52 micromol/L at the end of the experiment (P < 0.05). The elevated value of serum retinol for group B and C were 0.29 micromol/L and 0.14 micromol/L (both were P < 0.05). There was no difference before and after the experiment for control group D (P > 0.05). There was no significant difference on Hb concentration before and after the experiment as well as between groups (all were P > 0.05). In subjects of group A, serum iron concentration increased (P < 0.05) and serum ferrtin and transferrtin receptor concentration decreased significantly (both were P < 0.05) after VA supplement intervention. No such changes were observed in group B and C (P < 0.05).
Conclusion: It seems that the intervention of VA supplement with relative high dose of retinol at dietary level could enhance the iron status further in no-anemic healthy adults even without dietary iron supplementation.