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Iron as Ferrous Sulfate

Also known as: Iron(II) sulfate, ferrous sulphate, FeSO₄ · 7H₂O, Ferrous sulfate

Overview

Ferrous sulfate is a commonly used iron supplement, specifically effective for treating and preventing iron deficiency anemia. It is derived from natural sources and is highly bioavailable, which enhances its efficacy when taken orally. Found in a variety of foods such as red meat, fish, beans, and fortified cereals, iron is an essential mineral necessary for hemoglobin production and overall bodily functions. Ferrous sulfate supplementation is especially important for vulnerable populations, including pregnant women, children, and the elderly. The research supporting its use is robust, with multiple systematic reviews confirming its safety and effectiveness over many decades.

Benefits

Ferrous sulfate supplementation has several evidence-based benefits, particularly in improving hemoglobin levels. In children under five, it has been associated with a significant increase in hemoglobin levels, showing a pooled effect of 0.56 mg/dL compared to weekly iron dosing. For elderly individuals with iron deficiency anemia, a mean increase of 0.35 g/dL in hemoglobin levels has also been documented. While daily supplementation is favored, it does not significantly reduce anemia prevalence in children. Specifically, pregnant women and children benefit substantially from this supplement, although the elderly may experience gastrointestinal side effects. These findings are supported by a high quality of clinical evidence, highlighting the importance of dosage frequency and appropriate administration.

How it works

Ferrous sulfate works primarily through absorption in the gastrointestinal tract, particularly in the duodenum and proximal jejunum, where it is converted to ferrous iron. This iron is then transported into the bloodstream and used for hemoglobin and myoglobin production. The primary interaction occurs with the transferrin receptor, facilitating iron transport and utilization in the body. Its high bioavailability contributes to effective iron supplementation, making it a preferred choice for those suffering from deficiencies.

Side effects

Although generally safe when used appropriately, ferrous sulfate is commonly associated with gastrointestinal side effects, including nausea, vomiting, diarrhea, and abdominal pain, which occur in more than 5% of users. The odds of experiencing these side effects are significantly elevated compared to a placebo. Uncommon occurrences (1-5%) can include constipation and darkened stools. Rare side effects (less than 1%) may involve allergic reactions and anaphylaxis, necessitating caution in susceptible individuals. Additionally, ferrous sulfate may interact adversely with certain medications, such as antacids and proton pump inhibitors, which can impair iron absorption. It is contraindicated in conditions involving iron overload, such as hemochromatosis. Special populations, such as pregnant women, may face increased gastrointestinal issues.

Dosage

For effective treatment, the minimum effective dose of ferrous sulfate typically ranges from 30 to 60 mg of elemental iron per day, with the optimal dose for adults being 65-130 mg daily. In children, recommendations suggest 3-6 mg/kg/day of elemental iron. The upper limit should ideally not exceed 200 mg of elemental iron daily without medical guidance. It is recommended to take ferrous sulfate on an empty stomach to maximize absorption, although it can be taken with food to lessen gastrointestinal discomfort. The heptahydrate form (FeSO₄ · 7H₂O) is favored for its solubility, and absorption may be enhanced by vitamin C intake while being hindered by antacids.

FAQs

Is ferrous sulfate safe for everyone?

Ferrous sulfate is generally safe, but monitoring for gastrointestinal side effects is crucial, especially in special populations like pregnant women.

When is the best time to take ferrous sulfate?

It is best taken on an empty stomach to improve absorption but can be combined with food to minimize side effects.

How long until I see results from ferrous sulfate?

Improvements in hemoglobin levels can typically be expected within 4-6 weeks of consistent supplementation.

Can I take ferrous sulfate weekly instead of daily?

Daily dosing is more effective than weekly for improving hemoglobin levels, especially in children.

Research Sources

https://pubmed.ncbi.nlm.nih.gov/25700159/ – This systematic review and meta-analysis investigates gastrointestinal side effects associated with ferrous sulfate compared to placebo and intravenous iron, highlighting a significantly increased risk for patients treated with ferrous sulfate.
https://pubmed.ncbi.nlm.nih.gov/24068220/ – This systematic review examines the effectiveness of daily ferrous sulfate supplementation in preventing anemia in children, concluding that daily doses outperform weekly regimens in improving hemoglobin levels.
https://www.ncbi.nlm.nih.gov/books/NBK164178/ – This study reviews the efficacy of oral iron supplementation in elderly populations, showing significant increases in hemoglobin levels among those with iron deficiency anemia receiving ferrous sulfate.
https://pubmed.ncbi.nlm.nih.gov/25644019/ – This systematic analysis evaluates outcomes of ferrous sulfate supplementation, underscoring its effectiveness in raising hemoglobin levels while also considering frequency-dependent efficacy.
https://www.researchgate.net/publication/272686126_Ferrous_Sulfate_Supplementation_Causes_Significant_Gastrointestinal_Side-Effects_in_Adults_A_Systematic_Review_and_Meta-Analysis – A meta-analysis emphasizing the prevalence of gastrointestinal side effects in adults receiving ferrous sulfate, indicating a significant difference compared to control treatments.