Ferrous sulfate and iron bis-glycinate for low iron stores in schoolchildren
What it found
In 200 Mexican schoolchildren with low iron stores but no anemia, daily iron supplements raised ferritin levels, and the effect lasted 6 months after the supplements stopped.
The two iron forms worked about the same right after supplementation, but at 6 months ferritin was higher in the bis-glycinate chelate group.
What they found
Studies in people
Ferritin increase
Ferritin concentration rose significantly from the start to one week after supplementation and from the start to 6 months after supplementation. One week after supplementation, only 10% of children had low iron stores, compared with all children at the start.
Comparing iron forms
One week after supplementation, there was no difference in ferritin between the two iron compounds. At 6 months after supplementation, ferritin was higher in the group that received iron bis-glycinate chelate.
Low iron storage odds
There was no difference in the odds of having low iron storage between the two supplement groups at either time point.
Hemoglobin unchanged
Hemoglobin concentration did not change significantly in either group after supplementation.
Side effects
There were no cases where supplementation had to be stopped due to side effects. Twenty-two children (10.4%) had side effects like diarrhea, abdominal pain, nausea, constipation, or metallic taste for one or more days, with no significant difference between groups.
What the authors conclude
“The results of our study showed that a low iron dose of 30 mg/day for 90 days with either ferrous sulfate or iron bis-glycinate chelate significantly increased serum ferritin concentration in schoolchildren with low iron stores but no anemia and had negligible side effects.”
Also in their conclusions
- They conclude that supplementing with 30 mg/day of elemental iron, either as ferrous sulfate or iron bis-glycinate chelate for 90 days, increased ferritin concentration in schoolchildren with low iron stores, and this effect persisted 6 months after supplementation.
- They state that both treatments had negligible side effects and support the preventive effectiveness of this low-dose iron intervention to help prevent iron deficiency anemia.
- They caution that iron supplementation is no substitute for a balanced diet, and in areas where malaria is endemic, they would caution against extended use of iron supplementation, even in small doses, until safety studies have been conducted.
How it was done
Iron deficiency is one of the most common nutritional deficiencies worldwide, and it can harm immune response, physical capacity for work, and intellectual functions like attention even before anemia develops. The authors wanted to compare two iron compounds for preventing iron deficiency in schoolchildren.
They randomly assigned 200 schoolchildren aged 5 to 13 in Mexico City with low iron stores but no anemia to receive 30 mg of elemental iron daily as either ferrous sulfate or iron bis-glycinate chelate for 12 weeks. Iron status was checked at the start, one week after supplementation, and 6 months after supplementation.
What it can’t tell you
- This trial was in Mexican schoolchildren with low iron stores but no anemia, so the results may not apply to other groups or settings.
- The study did not measure other indicators of iron status like serum transferrin or total serum iron, so it cannot show how the supplements affected those.
- Many children dropped out by the 6-month check, so the longer-term results are based on fewer children.
The paper
- Title
- Effect of supplementation with ferrous sulfate or iron bis-glycinate chelate on ferritin concentration in Mexican schoolchildren: a randomized controlled trial
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Duque X, Martinez H, Vilchis-Gil J, et al (2014). Effect of supplementation with ferrous sulfate or iron bis-glycinate chelate on ferritin concentration in Mexican schoolchildren: a randomized controlled trial. Nutrition journal. doi:10.1186/1475-2891-13-71Free full textPubMed 25023784DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error