Mineral ·Strong evidence ·Reviewed May 2026
Gentle, highly bioavailable iron form that causes less GI distress than other forms.
The bottom line
Evidence rating strong. Most-documented uses: iron supplementation, anemia treatment, gentle on stomach. 15 sources indexed (1991–2025), with 17 interaction records on file.
Core mechanism
Amino acid chelation protects iron from binding phytates/tannins, maintaining bioavailability. Absorbed via amino acid transporters in addition to DMT1, reducing GI oxidative stress.7,3
Ranked by evidence and value.
Real-world pricing across three quality tiers. Assumes Ferrous Bisglycinate.
Assumes a daily dose delivering about 25-36 mg elemental iron. The sticker price is higher than sulfate, but better tolerability often improves real-world value. Updated 2026-04-02.
How much you'd eat to match a supplemental dose.
Supplemental-style iron doses are difficult to match from food alone once deficiency is present.
Dose: 18-36 mg elemental daily10
Timing: Morning with 100-250 mg vitamin C
Usually better tolerated than ferrous sulfate.
Dose: 25-36 mg elemental daily1,5
Timing: Empty stomach if tolerated
Use labs to guide duration; constipation is still possible.
Dose: 18-25 mg elemental daily
Timing: A few times weekly or daily depending on labs
Reduce or stop once ferritin is restored if dietary intake is adequate.
What to test, the optimal window inside the conventional range, and how long a response takes.
Gentler iron repletion should still raise ferritin gradually when the dose is effective.10,1
Track ferritin with CBC and transferrin saturation instead of relying on symptoms alone.
Serum iron should improve as repletion takes hold, but short-term fluctuation is expected.10,1
A fasting morning sample is preferred for trend comparisons.
TIBC often trends down as iron deficiency is corrected.7,1
Best interpreted with serum iron and transferrin saturation.
Transferrin saturation should rise as available iron improves.
Fasting sampling improves consistency for follow-up.
Where this appears in the symptom-to-supplement map, ranked by relevance.
Low iron stores are a common reversible driver of diffuse telogen shedding, and restoring ferritin can shorten the shedding phase.
Test serum ferritin first; supplement only if low (many dermatologists target ferritin above 30 to 50 ng/mL). Avoid iron if levels are normal or high, and confirm the cause with a clinician.
Heavy bleeding causes iron deficiency; bisglycinate restores ferritin with less GI distress than ferrous salts.1,2
Test ferritin and hemoglobin; alternate-day dosing improves absorption and tolerability.
Iron is required for hemoglobin synthesis and oxygen transport, so repletion directly addresses iron deficiency anemia.1,3
Confirm with ferritin and a full blood count before supplementing, since iron overload can be harmful; bisglycinate is gentler on the gut.
Blood loss at delivery and the demands of pregnancy frequently deplete iron stores, and correcting confirmed deficiency improves fatigue and oxygen delivery.3,14
Confirm with a ferritin test before dosing iron, since unnecessary iron can be harmful; bisglycinate is gentler on the gut than ferrous sulfate.
Postpartum and breastfeeding iron depletion (low ferritin) prolongs the shedding phase, and correcting a deficiency supports the return to normal hair-cycle balance.14
Only supplement iron after a ferritin test confirms low stores; unneeded iron can cause harm, so confirm with a clinician. Postpartum shedding usually self-resolves by 6 to 12 months regardless.
Low ferritin reduces oxygen delivery and is a common reversible cause of cold extremities, especially in menstruating women.1,6
Test ferritin first; target above 50 ng/mL for symptom relief.
Iron deficiency can coexist with and worsen autoimmune hair loss, so correcting low ferritin supports regrowth potential.
Test ferritin first and supplement only if low. Will not by itself reverse the autoimmune process.
Limited food intake and malnutrition risk in gastroparesis can lead to iron deficiency that worsens fatigue.
Only supplement to correct a confirmed deficiency; excess iron can constipate and is unsafe without testing.
Evidence-based stacks that include it, with the exact dose and timing each one uses.
Plant (non-heme) iron is absorbed less efficiently than heme iron, so vegetarians can be at higher risk of low iron stores. Iron bisglycinate is a chelated form that is generally well tolerated and well absorbed, but routine iron should be guided by labs because excess iron is harmful.12,1
Low brain iron is the most consistent reversible factor associated with restless legs, and oral iron repletion can ease symptoms when iron stores are low. Take this only after a ferritin test confirms low stores, because iron overload is harmful.1,2
Iron is the core nutrient for confirmed iron deficiency anemia, but it should be guided by ferritin, transferrin saturation, CBC response, and evaluation for the cause of deficiency. Stop when stores are repleted unless a clinician advises otherwise.7,3
Low ferritin is associated with worse ADHD symptoms in some studies, but iron should be used only after labs confirm low stores. Iron overload is harmful and anemia needs a cause identified.1,5
Even gentler iron forms can worsen iron overload if HFE-associated hemochromatosis risk is present and deficiency has not been confirmed first.
Recommendation: Use ferritin and transferrin saturation to justify treatment before supplementing, even when the product is marketed as a well-tolerated form.
Vitamin C dramatically increases non-heme iron bisglycinate absorption by reducing ferric iron bisglycinate (Fe3+) to ferrous iron bisglycinate (Fe2+) and forming a soluble chelate.
Recommendation: Take 200mg+ vitamin C with iron bisglycinate supplements to maximize absorption. Especially important for plant-based iron bisglycinate sources.
Calcium significantly inhibits both heme and non-heme iron bisglycinate absorption when taken simultaneously.
Recommendation: Separate iron bisglycinate and calcium by at least 2 hours. Take iron bisglycinate in the morning on an empty stomach, calcium with a different meal.
Iron Bisglycinate and zinc compete for the same absorption pathways when taken together in supplement form.
Recommendation: Take iron bisglycinate and zinc at different times of day, separated by at least 2 hours.
Both iron bisglycinate and B12 are essential for red blood cell production. Deficiency in either causes anemia.
Recommendation: If anemic, check both iron bisglycinate and B12 status. Supplementing only one may not resolve anemia if both are deficient.
Iron Bisglycinate is a cofactor for tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis.
Recommendation: Ensure adequate iron bisglycinate status when using L-tyrosine for cognitive support. Iron Bisglycinate deficiency impairs catecholamine synthesis.
ALA chelates metals including iron bisglycinate. May reduce iron bisglycinate absorption or redistribute iron bisglycinate stores.
Recommendation: Separate by 2+ hours. Avoid high-dose ALA if you have iron bisglycinate deficiency.
Iron Bisglycinate supplements can disrupt gut microbiome composition. However, certain probiotic strains may actually enhance iron bisglycinate absorption.
Recommendation: Separate by 2 hours. Some Lactobacillus strains can increase iron bisglycinate absorption, so probiotics may be beneficial for iron bisglycinate-supplementing individuals.
Vitamin A improves iron bisglycinate mobilization from stores and enhances erythropoiesis. Combined supplementation is more effective than either alone for anemia.
Recommendation: Supplementing both is more effective for iron bisglycinate-deficiency anemia than iron bisglycinate alone, especially in developing countries.
Magnesium and iron bisglycinate can compete for absorption when taken together. Separate for optimal absorption of both.
Recommendation: Take iron bisglycinate in the morning on an empty stomach. Take magnesium glycinate in the evening.
Iron Bisglycinate deficiency impairs thyroid hormone synthesis because thyroid peroxidase (TPO) is a heme-containing enzyme.
Recommendation: Address iron bisglycinate deficiency when treating thyroid issues. Iron Bisglycinate-deficient individuals may not respond well to iodine supplementation alone.
Ashwagandha has limited human research involving vitality and hematologic markers, but it is not an iron source and is not a substitute for iron therapy.
Recommendation: Treat iron deficiency with lab-guided care and clinician advice. Ashwagandha should not be used to replace prescribed or recommended iron supplementation.
Iron, including chelated forms like iron bisglycinate, binds ciprofloxacin in the gastrointestinal tract and forms insoluble complexes that prevent absorption. The reduction in ciprofloxacin bioavailability can exceed 50 percent. Although bisglycinate is marketed as gentler on the gut, it still contains free iron available for fluoroquinolone chelation in the intestinal lumen.
Recommendation: Take ciprofloxacin at least 2 hours before or 6 hours after any iron supplement, including bisglycinate. Do not take together in the same dose.
Numbered references. Citations throughout the page link here.
Meta-analysis of 17 RCTs found ferrous bisglycinate produced higher hemoglobin concentrations in pregnant women and 64% fewer GI adverse events compared to other iron salts.
Secrest AH, Norgan Radler C, Kelly J et al.. Glycoprotein Matrix-Bound Iron Improves Absorption Compared to Ferrous Bisglycinate Chelate and Ferrous Fumarate: A Randomized Crossover Trial. Cureus. 2025
Hamed H, Samie OMA, Motawie AA et al.. Amino Acid Chelated Iron Versus Ferric Ammonium Citrate on Iron Status in Egyptian Children with Iron Deficiency Anemia: A Randomized Controlled Study. Indian journal of hematology & blood transfusion : an official journal of Indian Society of Hematology and Blood Transfusion. 2025
Cirigliano E, Saint A, Pei LX et al.. Iron Supplementation with Ferrous Sulfate or Ferrous Bisglycinate for 12 Weeks Does Not Influence Group B Streptococcus Colonization in Cambodian Women: A Secondary Analysis of a Randomized Controlled Trial. The Journal of nutrition. 2025
Milman NT, Bergholt T. Low-Dose Prophylactic Oral Iron Supplementation (Ferrous Fumarate, Ferrous Bisglycinate, and Ferrous Sulphate) in Pregnancy Is Not Associated With Clinically Significant Gastrointestinal Complaints: Results From Two Randomized Studies. Journal of pregnancy. 2024
Fischer JAJ, Pei LX, Elango R et al.. Is a Lower Dose of More Bioavailable Iron (18-mg Ferrous Bisglycinate) Noninferior to 60-mg Ferrous Sulfate in Increasing Ferritin Concentrations While Reducing Gut Inflammation and Enteropathogen Detection in Cambodian Women? A Randomized Controlled Noninferiority Trial. The Journal of nutrition. 2023
RCT in pregnant women confirmed ferrous bisglycinate's efficacy and safety for iron deficiency control, noting amino acid chelation maintains bioavailability even with food inhibitors.
Hsu CY, Chen JC, Tsai YC et al.. Low-dose ferrous bisglycinate chelate supplementation in chronic kidney disease and hemodialysis patients. Journal of the Chinese Medical Association : JCMA. 2022
Iron bisglycinate chelate showed effective treatment of iron deficiency anemia comparable to polymaltose iron with good tolerability and fewer GI side effects.
Both ferrous sulfate and iron bis-glycinate chelate were effective for iron repletion in children, with absorption of ferrous bisglycinate being significantly higher than ferrous sulfate.
Milman N, Jønsson L, Dyre P et al.. Ferrous bisglycinate 25 mg iron is as effective as ferrous sulfate 50 mg iron in the prophylaxis of iron deficiency and anemia during pregnancy in a randomized trial. Journal of perinatal medicine. 2014
In 38 women, 37% experienced moderate-to-severe side effects only while taking ferrous sulfate vs 21% with the chelate formulation; bisglycinate was better tolerated for bloating, constipation, and nausea.
Ferrari P, Nicolini A, Manca ML et al.. Treatment of mild non-chemotherapy-induced iron deficiency anemia in cancer patients: comparison between oral ferrous bisglycinate chelate and ferrous sulfate. Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie. 2012
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