Elemental iron in ferrous sulfate
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Efficacy and Bioavailability of Elemental Iron in Ferrous Sulfate
Introduction to Elemental Iron in Ferrous Sulfate
Elemental iron is a critical component in the treatment and prevention of iron deficiency anemia (IDA). Ferrous sulfate is one of the most commonly used forms of iron supplements due to its high bioavailability and efficacy. This article synthesizes research findings on the efficacy, bioavailability, and side effects of ferrous sulfate compared to other iron compounds.
Efficacy of Ferrous Sulfate in Iron Deficiency Anemia
Comparison with Other Iron Compounds
Ferrous sulfate has been shown to be highly effective in increasing hemoglobin levels and improving iron status in various populations. In a study comparing ferrous sulfate, electrolytic iron, and hydrogen-reduced iron in Thai women, ferrous sulfate significantly increased serum ferritin and decreased serum transferrin receptor levels, indicating improved iron stores . Similarly, in pregnant women, ferrous bisglycinate at a lower dose was found to be as effective as ferrous sulfate in preventing iron deficiency and anemia, though ferrous sulfate was associated with more gastrointestinal complaints .
Pediatric and Adult Populations
In children with IDA, ferrous sulfate was more effective than iron polymaltose complex in increasing hemoglobin levels and reducing residual complaints . Another study in young children with nutritional IDA found that ferrous sulfate resulted in a greater increase in hemoglobin concentration compared to iron polysaccharide complex, with a higher proportion of complete resolution of IDA . In gastrectomized patients, ferrous sulfate was more effective than ferrous glycinate chelate in improving hematologic parameters and increasing ferritin levels .
Bioavailability of Ferrous Sulfate
Comparative Bioavailability
The bioavailability of ferrous sulfate is superior to many other forms of elemental iron. Research on rats demonstrated that the bioavailability of various commercial elemental iron powders was significantly lower than that of bakery-grade ferrous sulfate, with ferrous sulfate showing the highest relative biological value . This high bioavailability is attributed to the solubility and surface area of ferrous sulfate particles, which enhance iron absorption in the gut.
Absorption in Special Populations
In patients on continuous ambulatory peritoneal dialysis (CAPD), the absorption of ferrous sulfate was poor, similar to that of a polysaccharide ferric complex, indicating that certain medical conditions can affect iron absorption . However, in healthy individuals, ferrous sulfate showed a significant rise in serum iron levels, demonstrating its efficacy in iron repletion .
Side Effects and Tolerability
Gastrointestinal Side Effects
Ferrous sulfate is associated with gastrointestinal side effects, which can affect patient compliance. A study comparing a wax-matrix iron preparation with conventional ferrous sulfate tablets found that the conventional tablets had a higher incidence of adverse effects . However, the wax-matrix preparation, designed to reduce gastrointestinal discomfort, was better tolerated.
Dosage and Administration
Adherence to iron supplementation regimens can be challenging. A study in Ghana comparing single versus three-times-daily dosing of ferrous sulfate drops found that a single daily dose was as effective as multiple doses in treating anemia, with similar side effects . This suggests that simplifying dosing regimens may improve adherence without compromising efficacy.
Conclusion
Ferrous sulfate remains a highly effective and bioavailable form of elemental iron for the treatment and prevention of iron deficiency anemia. While it is associated with gastrointestinal side effects, its efficacy in increasing hemoglobin levels and improving iron stores is well-documented across various populations. Alternative formulations and dosing strategies may help mitigate side effects and improve patient compliance.
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