Table 2

Daily and twice-daily administration of 60 mg Fe (studies 2 and 3)

Iron bioavailabilityIron status
Time and day of administrationFractional Fe absorption (%)Fe absorbed (mg)PHep (nM)PF (µg/L)sTfR (mg/L)Body iron stores (mg/kg BW)
Study 2: Daily*8:00 am, d1NANA0.6 (0.5-8.9)16.2 (13.5-23.0)4.4 (1.7)3.5 (2.7)
8:00 am, d222.9 (10.5-49.4)13.8 (6.3-29.6)0.8 (0.4-6.1)15.5 (7.2-30.0)5.1 (1.3)2.7 (2.1)
8:00 am, d314.6 (7.2-28.3)§8.8 (4.6-17.0)§1.5 (0.3-8.5)26.7 (11.6-57.5)5 (1.5)4.7 (2.3)#
8:00 am, d15NANAND16.9 (7.3-34.0)5.1 (1.4)3.0 (1.7)
Study 3: Twice daily*10:00 am, d117.1 (8.5-37.3)10.2 (5.1-22.4)0.9 (0.3-3.7)13.6 (7.1-32.0)4.9 (1.1)2.3 (2.2)
4:00 pm, d212.5 (6.3-19.2)**7.5 (3.8-11.5)**4.1 (0.5-10.7)††15.9 (6.1-37.5)‡‡5.2 (1.3)2.5 (2.4)
8:00 am, d39.9 (4.4-16.3)**5.9 (2.6-9.8)**6.3 (1.3-14.1)††, §32.2 (19.3-57.8)a5.1 (1.4)5.2 (1.6)††
8:00 am, d15NANAND16.4 (8.4-53.1)4.6 (0.9)3.2 (2.2)
  • BW, body weight; NA, not applicable; ND, not determined; PF, plasma ferritin; PHep, plasma hepcidin; sTfR, soluble transferrin receptor.

  • Studies 2 and 3 are two distinct studies conducted with either daily or twice-daily administration of 60-mg supplements.

  • * In study 2, doses are given at 08:00 pm; in study 3, doses are given at 10:00 am and 5:00 pm to fasting subjects. All administrations were given to fasting subjects immediately after iron status determination.

  • Geometric means (range).

  • Means (SD). All doses 60 mg Fe as FeSO4, daily study, n = 16; twice-daily study, n = 13.

  • § Different from d1 (paired Student t test, P < .01).

  • Different from d1, d2 (P < .05).

  • Different from d1, d2, and d16 (P < .01).

  • # Different from d1, d2, and d16 (P < .05).

  • ** Different from other time points (P < .05).

  • †† Different from 10:00 am d1 (P < .01).

  • ‡‡ Different from preceding time point (P < .05).

  • ¶¶Different from daily study 8:00 am d2 (P < .05).

  • aDifferent from all other time points (P < .001).