Is ferrous sulfate (iron supplement) more effective than ferrous glycinate and ferrous aspartate for treating iron deficiency anemia?

Ferrous Sulfate vs. Ferrous Glycinate and Ferrous Aspartate for Iron Deficiency Anemia

No single formulation of oral iron has proven advantages over others, but ferrous sulfate is preferred as the least expensive iron formulation for treating iron deficiency anemia. 1

Efficacy Comparison

The 2024 American Gastroenterological Association (AGA) clinical practice update provides clear guidance on this question. According to their Best Practice Advice statement, there is no evidence that any particular oral iron formulation is superior in terms of efficacy 1. This recommendation is based on a comprehensive review of published literature and expert opinion.

The British Society of Gastroenterology guidelines similarly state that ferrous sulfate, ferrous gluconate, and ferrous fumarate are all equally effective in correcting iron deficiency anemia 1.

Cost and Accessibility Considerations

While all formulations have similar efficacy, ferrous sulfate is specifically recommended as the preferred option due to its lower cost 1. This makes it more accessible to patients and healthcare systems, which is an important consideration for a condition that affects a significant portion of the population.

Dosing Recommendations

• Ferrous sulfate: 200 mg three times daily (providing approximately 65 mg elemental iron per tablet) 1
• Alternative dosing: Recent evidence suggests once-daily dosing may be equally effective and better tolerated 1, 2
• Add vitamin C to improve absorption 1

Tolerability and Side Effects

All oral iron formulations can cause gastrointestinal side effects, which may impact compliance 3. Some newer formulations claim better tolerability, but the 2024 AGA guidelines do not recognize any formulation as having a proven advantage in this regard 1.

To improve tolerability:

• Consider once-daily dosing instead of multiple daily doses 1
• Try every-other-day dosing for patients with poor tolerance 1
• Use liquid preparations when tablets are not tolerated 1

When to Consider Alternative Approaches

Intravenous iron should be considered when:

• Patient does not tolerate oral iron (after trying at least two different preparations)
• Ferritin levels do not improve with a trial of oral iron
• Patient has a condition where oral iron is not likely to be absorbed (e.g., inflammatory bowel disease with active inflammation, after certain bariatric procedures) 1

Expected Response to Treatment

• Hemoglobin should rise by approximately 2 g/dL after 3-4 weeks of therapy 1
• If this response is not achieved, consider:
  • Poor compliance
  • Misdiagnosis
  • Continued blood loss
  • Malabsorption 1

Common Pitfalls to Avoid

1. Overcomplicating therapy: Despite marketing claims of newer formulations, there is no evidence they provide better outcomes 1, 3
2. Unnecessary parenteral iron: Reserve for specific indications as it's more expensive and carries risks of reactions 1
3. Inadequate duration: Treatment should continue beyond normalization of hemoglobin to replenish iron stores 1
4. Missing underlying causes: Always investigate and treat the underlying cause of iron deficiency 1
5. Excessive dosing: Higher doses don't necessarily improve outcomes and may worsen side effects 4

In conclusion, while various iron formulations are available on the market, the most recent and authoritative guidelines from the AGA (2024) clearly state that ferrous sulfate should be the preferred option due to its equivalent efficacy and lower cost compared to alternatives like ferrous glycinate and ferrous aspartate 1.