In IDNA adults  , iron supplementation is associated with reduced subjective measures of fatigue but not with objective improvements in physical capacity .
OBJECTIVE Iron supplementation in iron-deficiency anaemia is st and ard practice , but the benefits of iron supplementation in iron-deficient non-anaemic ( IDNA ) individuals remains controversial .
Our objective is to identify the effects of iron therapy on fatigue and physical capacity in IDNA adults .
Supplemental zinc lowers measures of iron status in young women with low iron reserves.
Zinc and iron compete during intestinal absorption , but postabsorptive interactions between these nutrients are less clear . Underst and ing these interactions is important to determine when supplementation with iron or zinc is proposed . The effect of zinc supplementation ( 22 mg Zn/d as zinc gluconate ) or of iron supplementation ( 100 mg Fe/d as ferrous sulfate ) for 6 wk on iron and zinc metabolism and absorption was evaluated in young women with low iron reserves . Young adult women ( ages 20 - 28 y ) , nonanemic but with low iron stores ( plasma ferritin < 20 microg/L ) , participated in the 70-d study . The women were divided in two groups ( zinc-supplemented , n = 11 ; iron-supplemented , n = 12 ) . The supplements were taken at bedtime .  Iron and zinc biochemical indices and intestinal absorption were measured on d 1 and 56 .  Radioiron and stable isotopes of zinc  were used to measure iron and zinc absorption from a test meal . In the iron-supplemented group , blood hemoglobin , plasma ferritin and the percentage of transferrin saturation increased ( P < 0.01 ) . Zinc indices did not change . In the zinc-supplemented group , plasma ferritin and the percentage of transferrin saturation decreased ( P < 0.05 ) , whereas the plasma transferrin receptor and erythrocyte zinc protoprophyrin levels increased ( P < 0.05 ) . Plasma and urinary zinc also increased ( P < 0.01 ) . Iron absorption ( % ) from the test meal increased ( P < 0.01 ) , whereas zinc absorption ( % ) decreased ( P < 0.01 ) compared with baseline in the Zn-supplemented women . Our results indicate that the use of iron supplements in women with marginal iron status improves iron indices with no effect on zinc status . However , use of a modest zinc supplement improves zinc indices , but also appears to induce a cellular iron deficiency and , possibly , further reduce iron status
In IDNA adults  , iron supplementation is associated with reduced subjective measures of fatigue but not with objective improvements in physical capacity .
OBJECTIVE Iron supplementation in iron-deficiency anaemia is st and ard practice , but the benefits of iron supplementation in iron-deficient non-anaemic ( IDNA ) individuals remains controversial .
Our objective is to identify the effects of iron therapy on fatigue and physical capacity in IDNA adults .