Effect of supplementation with ferrous sulfate or iron bis-glycinate chelate on ferritin concentration in Mexican schoolchildren: a randomized controlled trial

Table 3 Effects on mean concentration of ferritin according to iron compound and time of evaluation

Supplement and time of evaluation	Change in mean of ferritin (μg/l)	95% CI	P value
Supplement
Ferrous sulfate	Ref.
Bis-glycinate chelate	−0.18	−3.26 – 2.91	0.909
Time of evaluation
Baseline	Ref.
One week post-supplementation	20.16	17.11 – 23.22	0.001
6 months after supplementation	16.43	12.57 – 20.28	0.001
Additional increment in the group supplemented with Bis-glycinate chelate ^a
At baseline	Ref.
One week post-supplementation	0.87	−3.45 – 5.19	0.694
6 months after supplementation	6.04	0.64 – 11.43	0.028

Mixed-effects linear regression model with random intercept, adjusted by age and sex. Number of observations: 465, number of groups: 200, observations per group: 2.3 (1–3).
Ref. = Reference value.
^aInteraction between study stage and iron compound (bis-glycinate chelate vs. ferrous sulfate by time of evaluation).

ISSN: 1475-2891