Does methylation enhance iron absorption?

From the Guidelines

Methylated iron does not have a proven advantage in enhancing iron absorption compared to other forms of iron supplements. Iron supplements are available in various forms, including ferrous sulfate, ferrous gluconate, ferrous fumarate, and iron bisglycinate, but there is no specific "methylated iron" formulation commonly used for supplementation. For optimal iron absorption, ferrous forms of iron (like ferrous sulfate) are generally recommended as they are better absorbed than ferric forms.

Key Factors Influencing Iron Absorption

• Taking iron supplements with vitamin C can enhance absorption, as noted in a 2024 study 1 and further supported by a 2025 review 1, which highlights the importance of vitamin C in increasing non-haeme iron absorption.
• Calcium, tea, coffee, and certain foods can inhibit iron absorption.
• It's best to take iron supplements on an empty stomach, typically 1-2 hours before or after meals.
• The recommended dosage varies based on individual needs, but common therapeutic doses range from 60-200 mg of elemental iron daily, divided into 2-3 doses.

Clinical Considerations

Iron absorption occurs primarily in the duodenum and upper jejunum through specific transport proteins, and the body regulates absorption based on iron stores and requirements, which is why the form of iron matters less than other factors like timing and accompanying substances. A 2024 expert review 1 emphasizes the importance of adherence to a gluten-free diet in patients with iron-deficiency anemia and celiac disease to improve iron absorption. Additionally, a 2020 guideline 1 suggests that while there is no strong evidence that any oral iron formulation is more effective or better tolerated than others, factors such as gastrointestinal intolerance and malabsorption syndromes can influence the choice of iron supplement. An older guideline from 2011 1 also supports the use of ferrous sulphate as a simple and cost-effective option for iron supplementation, with the consideration of lower doses or alternative formulations for better tolerance.

From the Research

Iron Absorption and Methylate Iron

• The question of whether methylate iron is better for absorption than other forms of iron is complex and depends on various factors, including the individual's iron status and the specific formulation of the iron supplement 2, 3, 4.
• Studies have shown that ferrous salts, such as ferrous sulfate, are generally well-absorbed and effective in treating iron-deficiency anemia 3, 5.
• However, other forms of iron, such as ferric maltol and sucrosomial iron, may also be effective and have fewer gastrointestinal side effects 2, 4.
• The bioavailability of iron from different supplements can vary, with some studies suggesting that liquid-based supplements, such as Spatone Apple and Iron Vital F, may have higher bioavailability than ferrous sulfate tablets 4.
• The dosing schedule of iron supplements can also impact absorption, with alternate-day dosing potentially leading to increased iron absorption compared to consecutive-day dosing 6.

Comparison of Iron Supplements

• A study comparing ferrous gluconate with other iron supplements found that ferrous gluconate was more effective and better tolerated than other solid or liquid formulations containing elementary iron 3.
• Another study found that ferrous sulfate was more effective than iron polysaccharide complex in increasing hemoglobin concentration in young children with nutritional iron-deficiency anemia 5.
• However, other studies have suggested that iron polysaccharide complex may be better tolerated than ferrous sulfate, with fewer gastrointestinal side effects 5.

Factors Affecting Iron Absorption

• Iron absorption can be influenced by various factors, including the individual's iron status, the presence of other nutrients or substances that can enhance or inhibit iron absorption, and the specific formulation of the iron supplement 2, 4, 6.
• Hepcidin, a hormone that regulates iron metabolism, can also impact iron absorption, with elevated hepcidin levels potentially decreasing iron absorption 6.