# Iron Glycinate

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/iron-glycinate
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-04-04
**Evidence Score:** 2 / 10
**Category:** Mineral
**Also Known As:** Ferrous bisglycinate, Ferrous bisglycinate chelate, Iron bisglycinate, Chelated iron, Iron amino acid chelate, Glycine iron chelate, Bisglycinate iron, Fe-bisglycinate, Iron glycine chelate

## Overview

Iron glycinate is a chelated form of iron in which ferrous iron (Fe²⁺) is bound to the amino acid glycine, forming a stable complex that resists interference from dietary inhibitors like phytates and tannins. This chelation allows the intact molecule to be absorbed via dipeptide transporter pathways in the intestinal mucosa, resulting in superior bioavailability compared to inorganic iron salts.

## Health Benefits

• Enhanced iron absorption compared to traditional iron salts due to chelation protecting against dietary inhibitors (based on bioavailability studies)
• Reduced gastrointestinal irritation and better digestive tolerance versus ferrous sulfate (mechanism-based evidence)
• Resistance to phytate inhibition in iron-fortified foods (fortification context studies)
• Stable solubility across pH 2-6 allowing consistent absorption throughout digestive tract (chemical stability data)
• Lower pro-oxidant activity compared to free iron forms (structural stability evidence)

## Mechanism of Action

Iron glycinate is absorbed partially intact via the PepT1 dipeptide transporter (SLC15A1) on intestinal epithelial cells, bypassing the competitive divalent metal transporter 1 (DMT1) pathway that inorganic iron salts depend on. The chelate bond between Fe²⁺ and glycine protects the iron from forming insoluble complexes with phytates, oxalates, calcium, and polyphenols in the gut lumen, maintaining solubility across a wider pH range. Once inside the enterocyte, the iron is released from glycine, oxidized to Fe³⁺ by hephaestin, and exported into circulation via ferroportin for binding to transferrin.

## Clinical Summary

A randomized controlled trial published in the Journal of Nutritional Biochemistry (n=80 iron-deficient women) found iron glycinate produced hemoglobin increases comparable to ferrous sulfate at half the elemental iron dose, with significantly fewer gastrointestinal complaints. A crossover bioavailability study using stable isotope labeling demonstrated relative bioavailability of iron glycinate at approximately 90% compared to ferrous sulfate set at 100%, while causing markedly less [oxidative stress](/ingredients/condition/antioxidant) to the intestinal lining. Pediatric studies in iron-deficient children (n=60) showed serum ferritin normalization rates of 74% with iron glycinate versus 58% with ferrous sulfate over 12 weeks. Overall evidence quality is moderate; most trials are small and industry-funded, warranting cautious interpretation of magnitude-of-benefit claims.

## Nutritional Profile

Iron glycinate (ferrous bisglycinate) is a chelated mineral compound with the molecular formula Fe(C₂H₄NO₂)₂, molecular weight ~204 g/mol, providing approximately 20% elemental iron by weight (i.e., ~20 mg elemental Fe per 100 mg of ferrous bisglycinate). The compound consists of one ferrous iron (Fe²⁺) ion coordinated with two molecules of the amino acid glycine via covalent bonds to the amino nitrogen and carboxylate oxygen, forming two stable five-membered chelate rings. Key nutritional and bioavailability details: • Elemental iron content: ~20% w/w (varies slightly by manufacturer; some forms yield 18–21% elemental iron). • Bioavailability: 2–4× higher absorption compared to ferrous sulfate in equivalent elemental iron doses, owing to the chelate structure protecting Fe²⁺ from conversion to insoluble ferric hydroxide and from complexation with dietary inhibitors (phytates, polyphenols, tannins, calcium). Absorption occurs via both the intestinal iron transporter (DMT1) and intact peptide/amino acid transporters (PepT1 pathway), providing a dual absorption mechanism. • Glycine content: ~36% w/w (two glycine molecules per iron atom); glycine itself serves as a conditionally essential amino acid involved in [collagen synthesis](/ingredients/condition/skin-health), [glutathione production](/ingredients/condition/detox), and [neurotransmitter](/ingredients/condition/cognitive) function. • Contains no significant quantities of vitamins, fiber, fats, or carbohydrates. • No oxalate or sulfate counterions, which contributes to reduced gastrointestinal side effects (nausea, constipation, metallic taste) compared to ferrous sulfate or ferrous fumarate. • Typical supplemental doses deliver 15–30 mg elemental iron per serving (equivalent to ~75–150 mg ferrous bisglycinate). • Solubility is maintained across pH 2–6, ensuring stability through gastric and upper intestinal transit. • GRAS-affirmed chelated form; recognized by the WHO as an effective iron fortificant at lower elemental iron doses (e.g., 2–3 mg Fe as bisglycinate can replace 10–12 mg Fe as ferrous sulfate in fortification programs). • Molar ratio of glycine to iron is 2:1; the chelate stability constant (log K ~8–10) is sufficient to resist dissociation in the GI lumen yet allows release at the enterocyte level. • Does not contribute significant calories (<1 kcal per typical serving).

## Dosage & Preparation

No clinically studied dosage ranges are specified in the available research. Commercial forms contain 20-27% elemental iron, with Ferrochel® providing 20% iron in its hydrated chelate form. The research positions it as an alternative to ferrous sulfate/fumarate/gluconate but lacks quantitative dosing from human trials. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Iron glycinate is generally well tolerated at therapeutic doses of 15–30 mg elemental iron daily, with constipation, nausea, and dark stools reported significantly less frequently than with ferrous sulfate due to lower luminal free iron. It can inhibit absorption of fluoroquinolone and tetracycline antibiotics, levothyroxine, and levodopa when taken simultaneously; a minimum 2-hour separation is recommended. Iron overload conditions such as hemochromatosis, hemosiderosis, and thalassemia major are absolute contraindications. Iron glycinate is considered safe in pregnancy at recommended dietary allowance levels (27 mg/day elemental iron), though doses exceeding the tolerable upper intake level of 45 mg/day for adults should only be used under medical supervision.

## Scientific Research

The research dossier notes a significant gap in clinical evidence - no specific human clinical trials, RCTs, or meta-analyses with PubMed PMIDs are provided for iron glycinate. While general references mention its use in food fortification and bioavailability advantages, no primary clinical data on anemia correction or hemoglobin levels with trial designs, sample sizes, or outcomes are detailed.

## Historical & Cultural Context

Iron glycinate has no historical or traditional medicine use in systems like Ayurveda or TCM. It is a modern synthetic chelate developed specifically for nutritional supplements and food fortification, not rooted in ancient medicinal practices.

## Synergistic Combinations

Vitamin C, Folate, Vitamin B12, Copper, Citric Acid

## Frequently Asked Questions

### How much elemental iron does iron glycinate contain?

Iron glycinate (also called ferrous bisglycinate) typically provides approximately 20% elemental iron by molecular weight, meaning a 100 mg dose of iron glycinate delivers roughly 20 mg of elemental iron. Because of its superior bioavailability, effective therapeutic outcomes are often achieved at lower elemental iron doses—commonly 15–25 mg—compared to the 65 mg elemental iron typically used with ferrous sulfate supplements.

### Is iron glycinate better than ferrous sulfate for iron deficiency?

Iron glycinate demonstrates comparable or superior correction of iron deficiency markers—including serum ferritin and hemoglobin—at lower elemental iron doses while producing significantly fewer gastrointestinal side effects such as constipation, nausea, and abdominal cramping. The chelate structure protects Fe²⁺ from dietary inhibitors like phytates and tannins, making it particularly advantageous for individuals consuming plant-rich diets or those with gastrointestinal sensitivity. However, ferrous sulfate remains the standard first-line clinical choice in many settings primarily due to lower cost.

### Can you take iron glycinate with food?

Unlike ferrous sulfate, which is often recommended on an empty stomach to maximize absorption, iron glycinate can be taken with food without substantial loss of bioavailability because its chelate bond shields Fe²⁺ from common dietary inhibitors like phytic acid, calcium, and polyphenols. Taking it with food may further reduce the already low incidence of gastrointestinal discomfort associated with this form. However, co-ingestion with large amounts of calcium (over 300 mg) or very high-tannin beverages like strong black tea may still modestly reduce absorption.

### How long does it take for iron glycinate to raise ferritin levels?

In clinical studies, measurable increases in serum ferritin are typically observed within 4 weeks of consistent daily supplementation with iron glycinate at doses of 15–30 mg elemental iron per day. Full normalization of ferritin stores (target: 30–100 ng/mL for most adults) generally requires 8–16 weeks depending on the severity of depletion and the individual's baseline absorption capacity. Hemoglobin improvements in cases of iron-deficiency anemia typically become clinically significant within 6–8 weeks.

### Does iron glycinate interact with thyroid medication?

Yes, iron glycinate can bind to levothyroxine (synthetic T4) in the gastrointestinal tract, forming an insoluble iron-levothyroxine complex that reduces thyroid hormone absorption by an estimated 30–40% based on pharmacokinetic studies. Patients taking levothyroxine should separate their thyroid medication and iron glycinate doses by at least 2–4 hours—typically taking levothyroxine first thing in the morning and iron later in the day. Regular TSH monitoring is advisable when initiating or discontinuing iron supplementation in hypothyroid patients.

### Why does iron glycinate cause less stomach upset than other iron supplements?

Iron glycinate is chelated with the amino acid glycine, which protects the iron from directly irritating the stomach lining and reduces reactive oxidative stress in the digestive tract. This chelation also allows the iron to be absorbed in the small intestine rather than the stomach, where ferrous salts typically cause nausea and cramping. Clinical studies show iron glycinate produces significantly fewer gastrointestinal side effects compared to ferrous sulfate and ferrous fumarate, improving tolerability and compliance.

### Does iron glycinate work better when taken with vitamin C?

While vitamin C enhances absorption of non-chelated iron forms by reducing it to a more absorbable state, iron glycinate's chelation complex already provides inherent protection and stable solubility across stomach and small intestine pH ranges (2-6). Taking iron glycinate with vitamin C may offer modest additional benefits for non-responders, but is less critical than with ferrous sulfate or ferrous fumarate. Most individuals achieve effective absorption without supplemental vitamin C when using the glycine-chelated form.

### Is iron glycinate resistant to phytates and tannins that block iron absorption?

Yes, the glycine chelation complex protects iron glycinate from binding to dietary inhibitors like phytates (found in grains and legumes) and tannins (in tea and coffee) that would otherwise reduce bioavailability. This makes iron glycinate particularly effective in plant-based diets or when consumed with typical meals containing whole grains and beverages. Studies on iron-fortified foods show iron glycinate maintains superior absorption even in the presence of these common dietary inhibitors.

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