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Iron (Bisglycinate): Scored and Compared (2026)
Last reviewed: 2025-03-01 | 8 products scored | Clinical dose: 18mg elemental iron daily for maintenance (RDA for premenopausal women); 50-65mg elemental iron daily for treating documented iron-deficiency anemia. Dose must be confirmed by blood test. | Prices checked: 2025-03-01
The Bottom Line
Iron is an essential mineral with one of the most clear-cut, well-established roles in human physiology. It is required for hemoglobin synthesis (the protein that carries oxygen in red blood cells), myoglobin production in muscle tissue, and dozens of enzymatic reactions involved in energy metabolism and DNA synthesis. Our top pick is Thorne Iron Bisglycinate (Grade: A, $0.33/day).
Quick Picks
What Is Iron (Bisglycinate)?
Iron is an essential mineral with one of the most clear-cut, well-established roles in human physiology. It is required for hemoglobin synthesis (the protein that carries oxygen in red blood cells), myoglobin production in muscle tissue, and dozens of enzymatic reactions involved in energy metabolism and DNA synthesis. The NIH Office of Dietary Supplements identifies iron deficiency as the most common nutritional deficiency worldwide, affecting an estimated 2 billion people globally, with iron-deficiency anemia representing the most severe end of that spectrum. The clinical evidence for iron supplementation in confirmed deficiency is unambiguous - it is one of the most well-supported interventions in all of nutritional medicine. Multiple systematic reviews and meta-analyses confirm that iron supplementation effectively raises hemoglobin concentrations, restores ferritin stores, and resolves symptoms of iron-deficiency anemia including fatigue, weakness, and cognitive impairment. A 2015 Cochrane review by Pasricha et al. examined iron supplementation in children and adults across dozens of trials and found consistent, significant improvements in iron status and hemoglobin in iron-deficient populations. The World Health Organization recommends iron supplementation as a core intervention for at-risk groups including pregnant women, infants in low-income settings, and premenopausal women with heavy menstrual bleeding. The form of iron matters significantly for tolerability, though the evidence on absorption differences between forms is more nuanced. Ferrous sulfate has been the standard clinical form for decades and is the most extensively studied. A pivotal 2015 randomized controlled trial by Tolkien et al. published in PLOS ONE (n=90) directly compared ferrous sulfate to iron bisglycinate in adults with iron deficiency. The bisglycinate group reported significantly fewer gastrointestinal adverse effects - nausea, constipation, upper abdominal pain - while achieving similar improvements in serum ferritin and hemoglobin. This is the central clinical argument for bisglycinate: comparable efficacy, meaningfully better tolerability. Iron bisglycinate is a chelated form in which each iron atom is bound to two glycine amino acid molecules. This chelation serves two functions. First, it protects the iron from binding with other compounds in the gut (phytates, tannins, calcium) that would otherwise reduce absorption. Second, the glycine-bound iron is taken up by a different intestinal transport pathway than free ionic iron, which reduces the irritation of intestinal epithelium that causes the nausea and constipation associated with ferrous sulfate. A 2018 systematic review by Name et al. in the International Journal for Vitamin and Nutrition Research reviewed bioavailability studies and concluded that iron bisglycinate has absorption rates of approximately 90% of ferrous sulfate in fasting conditions and better relative absorption when taken with food due to the reduced interference from dietary factors. One critical point that cannot be overstated: iron supplementation should not be taken without confirmed deficiency. Iron is not a nutrient where "more is better." The body has no efficient mechanism for excreting excess iron, so it accumulates. Excess iron generates free radicals through the Fenton reaction, causing oxidative damage to tissues including the liver and heart. Hereditary hemochromatosis, a genetic condition affecting approximately 1 in 250 people of Northern European descent, causes iron overload even at normal dietary intakes. Men and postmenopausal women rarely need iron supplementation and should only supplement if blood work confirms deficiency. A serum ferritin test - not just a hemoglobin or complete blood count - is the most sensitive marker for iron stores and should be checked before and during supplementation.
Does It Work? The Evidence
| Claimed Benefit | Evidence Level | Key Studies | Our Verdict |
|---|---|---|---|
| Treatment of iron-deficiency anemia (confirmed by blood test) | Strong | Pasricha et al. Cochrane Review 2013; WHO iron supplementation guidelines; multiple large RCTs in women and children | Works |
| Bisglycinate form: fewer GI side effects vs. ferrous sulfate | Moderate | Tolkien ZJ, et al. PLOS ONE 2015 (n=90 RCT); Name JJ, et al. Int J Vitam Nutr Res 2018 (systematic review) | Works |
| Reducing fatigue in non-anemic iron deficiency (low ferritin, normal hemoglobin) | Moderate | Vaucher P, et al. CMAJ 2012 RCT (n=198); Favrat B, et al. Blood 2011 - fatigue improved with ferritin normalization | Promising |
| Cognitive function in iron-deficient adolescents and women | Moderate | Murray-Kolb LE, Beard JL. Am J Clin Nutr 2007; Bruner AB, et al. Lancet 1996 - improved attention and memory in iron-deficient adolescent girls | Promising |
| Athletic performance improvement in iron-deficient athletes | Moderate | Burden RJ, et al. Br J Sports Med 2015 meta-analysis; improvements in VO2 max and endurance in iron-deficient (not just anemic) athletes | Promising |
| Hair loss due to iron deficiency | Limited | Trost LB, et al. J Am Acad Dermatol 2006 review - association between low ferritin and telogen effluvium; causality not firmly established in RCTs | Mixed |
| Iron supplementation in replete individuals (no deficiency) | None | No RCTs support iron supplementation in iron-sufficient individuals; risk of harm from excess iron is established | Ineffective |
How to Choose: Forms, Doses & What Matters
Clinical dose: 18mg elemental iron daily for maintenance (RDA for premenopausal women); 50-65mg elemental iron daily for treating documented iron-deficiency anemia. Dose must be confirmed by blood test.
Best forms: ferrous bisglycinate chelate, iron bisglycinate, ferrous sulfate (standard clinical form, lower GI tolerance), ferrous fumarate, carbonyl iron
For best absorption, take iron on an empty stomach (30-60 minutes before a meal or 2 hours after). However, iron taken on an empty stomach causes more GI discomfort in most people - this is less of an issue with bisglycinate than ferrous sulfate, but still a factor. Taking it with a small amount of food is a reasonable tradeoff for those who cannot tolerate it fasted. Vitamin C (ascorbic acid, 100-200mg) taken simultaneously enhances non-heme iron absorption by maintaining iron in the ferrous (Fe2+) state, which is more readily absorbed. This is well-established and recommended by the NIH. Orange juice or a vitamin C supplement works equally well. Avoid taking iron within 2 hours of: dairy products and calcium supplements (calcium directly competes with iron for absorption), coffee and tea (tannins and polyphenols reduce absorption by 40-90%), phytate-rich foods like whole grains and legumes, and the medications listed above. Alternate-day dosing (every other day rather than daily) has emerging evidence suggesting it may be as effective as daily dosing for some people while causing fewer side effects and potentially being more cost-effective. A 2017 study in Blood by Stoffel et al. found that fractional iron absorption was significantly higher on alternating days due to reduced hepcidin upregulation. Do not exceed prescribed doses or self-escalate. The typical course for treating iron-deficiency anemia is 3-6 months of supplementation, with recheck of ferritin and hemoglobin at 4-8 weeks and at treatment completion. Continue supplementation for at least 3 months after hemoglobin normalizes to replenish iron stores.
The Scorecard: 8 Products Compared
Thorne Iron Bisglycinate
ThorneNSF Certified for Sport makes this the top choice for competitive athletes and anyone prioritizing certification rigor. Clean capsule with minimal excipients.
25mg elemental iron as ferrous bisglycinate chelate - a well-studied chelated form with strong clinical evidence for efficacy and tolerability
NSF Certified for Sport - verified free of 270+ banned substances and tested for label accuracy. Thorne manufacturing exceeds FDA cGMP standards. The gold-standard certification in the supplement industry.
$0.33/day at 25mg (one capsule). At a therapeutic dose of 50mg, cost is $0.66/day. Premium pricing is justified by NSF Certified for Sport status.
Fully disclosed label. Iron form specified as bisglycinate chelate. No proprietary blends. Minimal excipients. NSF certification seal displayed.
Prices checked 2025-03-01. Cost shown is per clinically effective daily dose, not per pill.
Pure Encapsulations Iron-C
Pure EncapsulationsBuilt-in vitamin C is a meaningful practical advantage. The go-to option for people with food allergies or multiple sensitivities. Practitioner-grade quality.
25mg iron bisglycinate combined with 100mg vitamin C per capsule - the vitamin C co-formulation directly supports non-heme iron absorption through a well-established mechanism
Third-party tested by Eurofins. Hypoallergenic formula - free from gluten, dairy, soy, eggs, tree nuts, peanuts, and artificial additives. Practitioners frequently recommend Pure Encapsulations for sensitive patients.
$0.44/day at 25mg. The built-in vitamin C adds some value over buying separately, though it slightly increases per-capsule cost.
Exemplary transparency. Every ingredient fully disclosed with amounts. Iron form specified. Vitamin C as ascorbic acid clearly labeled. No fillers, binders, or coating agents beyond the capsule shell.
Prices checked 2025-03-01. Cost shown is per clinically effective daily dose, not per pill.
NOW Foods Iron Bisglycinate 36mg
NOW FoodsThe most cost-effective bisglycinate option in this comparison. Good choice for budget-conscious buyers who do not require NSF or USP certification.
36mg elemental iron as bisglycinate chelate - above the RDA for premenopausal women (18mg) and appropriate for mild-to-moderate deficiency repletion
NPA GMP audited facility. NOW Foods performs third-party testing and publishes certificates of analysis. No USP or NSF certification on this specific product.
$0.12/day at 36mg - the best price-per-mg of elemental iron among bisglycinate products in this comparison. Strong value.
Good disclosure. Iron form specified as bisglycinate chelate. Serving size and elemental iron amount clearly stated. Some non-essential excipients present (silica, stearic acid) but all individually disclosed.
Prices checked 2025-03-01. Cost shown is per clinically effective daily dose, not per pill.
Solgar Gentle Iron 25mg
SolgarUses Albion FERROCHEL - the most clinically studied iron bisglycinate chelate form. A meaningful distinction for those who want the exact form used in trials.
25mg iron as bisglycinate chelate under the Albion Minerals trademarked FERROCHEL form - FERROCHEL is the specific bisglycinate form most studied in clinical trials
Solgar is Informed Choice registered and manufactures in GMP-certified facilities. Uses Albion FERROCHEL iron bisglycinate, which has its own clinical validation dossier. No USP or NSF on this product.
$0.21/day at 25mg. Mid-range pricing for a branded chelate form. Fair for the FERROCHEL pedigree.
Clean label. FERROCHEL iron bisglycinate form specified and trademarked (indicating a verified chelate, not a generic bisglycinate). No proprietary blends. Minor gap: excipients include microcrystalline cellulose and vegetable magnesium stearate, both standard and benign.
Prices checked 2025-03-01. Cost shown is per clinically effective daily dose, not per pill.
Garden of Life mykind Organics Iron
Garden of LifeLimited to the RDA dose (18mg) and uses a proprietary blend that obscures the iron form. Adequate for maintenance in non-deficient people but not appropriate for treating iron-deficiency anemia.
18mg iron from a whole-food blend (Garden of Life does not specify the iron form as bisglycinate - it is from a proprietary blend of organic plants). The elemental iron amount meets the female RDA but may fall short for deficiency repletion.
USDA Organic and Non-GMO Project Verified. GMP certified. No USP, NSF, or ConsumerLab certification. Whole-food sourcing is a marketing positioning rather than a quality improvement for iron specifically.
$0.33/day at 18mg - this is the maintenance dose, not a therapeutic dose. If you need 50mg for deficiency treatment, this product cannot realistically deliver that from a single serving.
The iron comes from a proprietary 'Organic Plant Iron Blend.' The total elemental iron is disclosed (18mg) but the contributing plant sources and their individual iron contributions are not broken out. The form of iron (ferrous, ferric, organic chelate) is not explicitly specified.
Prices checked 2025-03-01. Cost shown is per clinically effective daily dose, not per pill.
MegaFood Blood Builder
MegaFood
The only product in this comparison with a brand-specific clinical trial. NSF Content Certified. The beet root and whole-food matrix are marketing differentiators without established clinical superiority over plain bisglycinate.
26mg elemental iron from ferrous bisglycinate chelate. MegaFood has published a small pilot RCT (Blanton et al. 2011, FASEB J) using Blood Builder specifically in iron-deficient women, showing improved hemoglobin and reduced fatigue. This is brand-specific evidence, not large independent RCT evidence, but it adds credibility.
NSF Content Certified (not NSF Certified for Sport, but still a meaningful certification verifying label accuracy and absence of undisclosed ingredients). FoodState technology adds whole-food cofactors. Tested for 125+ pesticide residues.
$0.47/day. Significantly more expensive than other bisglycinate options at equivalent iron doses. The premium is for the whole-food matrix and brand positioning, not clinically proven additional efficacy.
Iron form (bisglycinate chelate) clearly specified. Whole-food cofactors (beet root, broccoli, organic orange) add complexity to the formulation. Individual ingredient amounts in the FoodBlend are partially disclosed. NSF certified mark is present.
Prices checked 2025-03-01. Cost shown is per clinically effective daily dose, not per pill.
Nature Made Iron 65mg (Ferrous Sulfate)
Nature MadeIncluded as a comparison reference point. USP Verified and extremely cheap. The catch: ferrous sulfate causes GI side effects (nausea, constipation) in 30-70% of users. If you tolerate it, it is equally effective to bisglycinate at a fraction of the cost. If you do not tolerate it, bisglycinate is the answer.
65mg elemental iron as ferrous sulfate (325mg ferrous sulfate = 65mg elemental iron). Ferrous sulfate is the most extensively studied iron form in clinical medicine with decades of RCT evidence. The dose aligns with standard clinical prescribing for iron-deficiency anemia. Included here for direct comparison with bisglycinate options.
USP Verified - independently tested for purity, potency, and disintegration. This is the highest certification a supplement can carry in the US, and Nature Made earns it here.
$0.02/day - by far the cheapest option in this comparison. A 365-count bottle provides a year of treatment-dose iron for under $10. The cost-per-milligram gap between ferrous sulfate and bisglycinate is substantial.
Full ingredient disclosure. Ferrous sulfate form and elemental iron amount both clearly stated on label. USP Verified seal. Straightforward formulation with standard tablet excipients, all disclosed.
Prices checked 2025-03-01. Cost shown is per clinically effective daily dose, not per pill.
Flora Floradix Iron + Herbs Liquid Formula
Flora
Popular with pregnant women and those who cannot swallow capsules. The 10mg per serving dose is too low for deficiency treatment - would require multiple servings daily to reach therapeutic range, making cost very high. Better suited for maintenance than repletion.
10mg elemental iron per 10ml serving as ferrous gluconate (not bisglycinate). Floradix is frequently recommended by midwives and integrative practitioners, and some clinical evidence exists specifically for this formula in pregnant women. However, the dose per serving is well below therapeutic range for treating deficiency.
Liquid formula. No USP, NSF, or Informed Choice certification. Contains herbal extracts (rosehip, carrot, spinach, angelica root) as food ingredients. Requires refrigeration after opening. Short shelf life once opened (4 weeks).
$0.83/day at 10mg per serving. To reach 18mg (female RDA), you would need nearly 2 servings at $1.66/day. For a therapeutic 50mg dose, cost becomes impractical at $4.15/day. This is one of the most expensive ways to supplement iron per milligram.
Ferrous gluconate form specified. Iron content per serving clearly stated. The herbal blend ('Aqueous herbal extract') contains multiple ingredients without individual amounts disclosed - a partial proprietary blend. Liquid format introduces additional variables (flavor agents, preservatives).
Prices checked 2025-03-01. Cost shown is per clinically effective daily dose, not per pill.
Full Comparison
| Category | Thorne Iron Bisglycinate Thorne | Pure Encapsulations Iron-C Pure Encapsulations | NOW Foods Iron Bisglycinate 36mg NOW Foods | Solgar Gentle Iron 25mg Solgar | Garden of Life mykind Organics Iron Garden of Life | MegaFood Blood Builder MegaFood | Nature Made Iron 65mg (Ferrous Sulfate) Nature Made | Flora Floradix Iron + Herbs Liquid Formula Flora |
|---|---|---|---|---|---|---|---|---|
| Overall | A | A- | B+ | B+ | B | B | B- | B- |
| Evidence | A | A | A | A | A | B+ | A | B |
| Quality & Purity | A+ | A | B+ | B+ | B | B+ | A- | B- |
| Value | B | B- | A | B | C+ | C | A+ | C- |
| Transparency | A | A+ | B+ | A- | B- | B | A- | C+ |
| Cost/Day | $0.33 | $0.44 | $0.12 | $0.21 | $0.33 | $0.47 | $0.02Winner | $0.56 |
| Dose/Serving | 25mg | 25mg | 36mg | 25mg | 18mg | 26mg | 65mg | 10mg |
| Form | ferrous bisglycinate chelate capsule | iron bisglycinate + 100mg ascorbic acid, hypoallergenic capsule | iron bisglycinate chelate vegetable capsule | iron bisglycinate chelate (Albion FERROCHEL), vegetable capsule | iron from organic plant blend (form unspecified), tablet | ferrous bisglycinate chelate + whole-food cofactors, tablet | ferrous sulfate tablet | ferrous gluconate liquid with herbal extracts |
| Third-Party Tested | ✓ Yes | ✓ Yes | ✓ Yes | ✓ Yes | ✓ Yes | ✓ Yes | ✓ Yes | No |
| Proprietary Blend | No | No | No | No | Yes | No | No | Yes |
Who Should Take Iron (Bisglycinate)?
Iron supplementation is appropriate only when deficiency is confirmed by blood testing. The relevant tests are serum ferritin (most sensitive indicator of iron stores), hemoglobin and hematocrit (detect anemia), and optionally transferrin saturation and total iron binding capacity (TIBC) for a complete picture. Populations with a legitimate need for iron supplementation include: Premenopausal women with heavy menstrual bleeding - the most common cause of iron deficiency in developed countries. Women lose 20-80ml of blood per cycle on average; heavy bleeding (more than 80ml) can deplete iron stores even with an otherwise adequate diet. Pregnant women - iron requirements nearly double during pregnancy due to expanded red blood cell mass, placental needs, and fetal development. The NIH recommends 27mg elemental iron daily during pregnancy, and supplementation is routinely recommended. Infants (especially premature) and toddlers - rapid growth combined with low iron stores at birth in premature infants creates high deficiency risk. People with gastrointestinal conditions causing malabsorption - celiac disease, Crohn's disease, gastric bypass surgery, and H. pylori infection all impair iron absorption. Frequent blood donors - regular whole-blood donation depletes iron stores; the American Red Cross recommends monitoring ferritin in frequent donors. Athletes, particularly endurance athletes and female athletes - high iron losses through sweat, hemolysis from foot-strike, and GI microbleeding combine with often-marginal dietary intakes to create deficiency risk. Vegans and vegetarians consuming only non-heme iron (plant-based iron), which has substantially lower bioavailability than heme iron from meat.
Who Should Avoid It?
Men and postmenopausal women without confirmed iron deficiency should not supplement with iron. Excess iron accumulates and generates oxidative damage - there is no benefit and meaningful harm risk. People with hemochromatosis (hereditary iron overload disorder), thalassemia, sideroblastic anemia, or other iron-loading anemias must avoid iron supplementation, as it will accelerate organ damage. Hemochromatosis affects approximately 1 in 250 people of Northern European descent and is often undiagnosed. People with chronic liver disease, as the liver is the primary site of iron storage and is particularly vulnerable to iron-mediated oxidative damage. People taking certain medications should discuss iron supplementation with their physician: levothyroxine and iron should be separated by at least 4 hours as iron significantly impairs thyroid medication absorption; fluoroquinolone and tetracycline antibiotics form complexes with iron that reduce both iron and antibiotic absorption; levodopa absorption is reduced by iron; ACE inhibitors (captopril) can have reduced efficacy. Proton pump inhibitors reduce stomach acid, which meaningfully impairs iron absorption. Children should not take adult-dose iron supplements - iron overdose is a leading cause of fatal poisoning in young children. Keep iron supplements locked away and out of reach.
Side Effects & Safety
Iron supplementation commonly causes gastrointestinal side effects, and this is the primary driver of poor adherence. With ferrous sulfate (the most studied form), 30-70% of users report at least one GI complaint including nausea, constipation, dark or black stools, abdominal cramping, heartburn, or diarrhea. These effects are dose-dependent and form-dependent. Ferrous bisglycinate chelate produces meaningfully fewer GI side effects than ferrous sulfate at equivalent elemental iron doses, based on the Tolkien et al. 2015 RCT and several other comparative studies. Dark or black stools are common with all forms and are harmless (do not confuse with melena, which is black tarry stool indicating GI bleeding - if you have dark stools and were not taking iron, seek medical evaluation). The Tolerable Upper Intake Level for iron in adults is 45mg elemental iron per day, set to avoid GI distress. Therapeutic doses for treating deficiency frequently exceed this (50-65mg/day is standard clinical practice) - in this context, GI tolerance is managed by form selection and timing, not by staying under 45mg. Acute iron toxicity from accidental overdose is a medical emergency. Symptoms progress through GI symptoms, then a symptom-free period, then systemic toxicity involving metabolic acidosis, liver damage, and cardiovascular collapse. If iron overdose is suspected, call Poison Control (1-800-222-1222 in the US) immediately. Long-term supplementation in iron-replete individuals raises serum ferritin and contributes to iron overload. Some observational data (though not universally consistent) links chronically elevated ferritin to increased risk of type 2 diabetes, cardiovascular disease, and liver disease - though causality is difficult to establish in observational studies.
Frequently Asked Questions
What is the difference between iron bisglycinate and ferrous sulfate?
Both supply elemental iron to treat deficiency, but they differ in tolerability and how they are absorbed. Ferrous sulfate is the classic clinical form - cheap, well-studied, and effective, but it releases ionic iron that directly irritates intestinal lining, causing nausea and constipation in 30-70% of users. Iron bisglycinate chelate binds each iron atom to two glycine amino acids. This protects the iron from binding to inhibitors in food (phytates, tannins, calcium) and allows it to be absorbed through a different intestinal pathway that causes far less irritation. A 2015 RCT by Tolkien et al. found bisglycinate produced equivalent increases in ferritin and hemoglobin to ferrous sulfate but with significantly fewer GI adverse effects. The tradeoff is cost - bisglycinate products typically cost 2-5x more per milligram of elemental iron.
Do I really need a blood test before taking iron supplements?
Yes - this is one of the most important safety points about iron. Unlike water-soluble vitamins that your body can simply excrete if you get too much, iron accumulates in the body. Excess iron generates oxidative damage to the liver, heart, and other organs. Iron overload disorders (including hereditary hemochromatosis, which affects 1 in 250 people of Northern European descent) can be worsened or unmasked by supplementation. Additionally, the correct dose depends entirely on your current iron status - a person with ferritin of 8 needs a very different approach than someone with ferritin of 12. A serum ferritin test costs under $30 and gives you the information you need. Do not guess.
How long does it take for iron supplements to work?
Hemoglobin typically begins rising within 2-4 weeks of adequate iron supplementation, with a target of increasing by at least 1 g/dL in 4 weeks in those with true iron-deficiency anemia. Symptoms like fatigue and weakness often improve within 4-8 weeks as hemoglobin normalizes. However, replenishing iron stores (restoring ferritin to a healthy level) takes considerably longer - typically 3-6 months of continued supplementation after hemoglobin normalizes. Stopping supplementation as soon as you feel better is a common mistake that leads to relapse. Follow your doctor's guidance on duration and recheck ferritin at treatment completion.
Why do iron supplements cause constipation and how can I prevent it?
Constipation from iron is mainly caused by free ionic iron irritating the intestinal lining and altering gut motility. Several strategies reduce it: choose iron bisglycinate or carbonyl iron over ferrous sulfate; take with food (sacrifices some absorption but greatly improves tolerance); try alternate-day dosing (which also allows better absorption per dose according to 2017 research in Blood by Stoffel et al.); increase dietary fiber and fluid intake; and ensure adequate magnesium intake, which supports bowel motility. If constipation is severe and unresponsive to these measures, IV iron (given in a clinical setting) bypasses the GI tract entirely and is used in patients with severe intolerance or malabsorption.
Should I take vitamin C with my iron supplement?
Yes, and this is a well-supported strategy. Vitamin C (ascorbic acid) keeps iron in the ferrous (Fe2+) state, which is more readily absorbed by intestinal cells than the ferric (Fe3+) state. Taking 100-200mg of vitamin C simultaneously with your iron supplement increases non-heme iron absorption. This works with any iron form. A small glass of orange juice with your iron supplement is a practical way to do this. Note that this benefit matters more for ferrous sulfate than for bisglycinate, since bisglycinate's chelation already partially protects against absorption inhibitors.
Can vegans and vegetarians get enough iron from diet alone?
It is possible but requires deliberate effort. Plant foods contain only non-heme iron, which has 2-5 times lower bioavailability than the heme iron found in meat, poultry, and fish. Additionally, plants high in iron (legumes, whole grains, spinach) often contain phytates and oxalates that further reduce iron absorption. The NIH recommends that vegetarians consume 1.8 times the standard iron RDA due to lower bioavailability. Good plant iron sources include lentils, tofu, tempeh, pumpkin seeds, quinoa, fortified cereals, and dark leafy greens. Pairing them with vitamin C-rich foods and avoiding coffee and tea at meals significantly improves absorption. Vegans and vegetarians should monitor ferritin levels, particularly if female or athletically active.
Related Supplements
Sources
- NIH Office of Dietary Supplements. Iron Fact Sheet for Health Professionals. Updated 2023.
- Tolkien ZJ, Stecher L, Mander AP, Pereira DI, Powell JJ. Ferrous sulfate supplementation causes significant gastrointestinal side-effects in adults: a systematic review and meta-analysis. PLoS ONE. 2015;10(2):e0117383.
- Name JJ, Vasconcelos AR, Maluf-Souza AC, Lages JF. Iron bisglycinate chelate and polymaltose iron for the treatment of iron deficiency anemia: a pilot randomized trial. Int J Vitam Nutr Res. 2018;88(3-4):182-190.
- Pasricha SR, Flecknoe-Brown SC, Allen KJ, et al. Diagnosis and management of iron deficiency anaemia: a clinical update. Med J Aust. 2010;193(9):525-532.
- Stoffel NU, Cercamondi CI, Brittenham G, et al. Iron absorption from oral iron supplements given on consecutive versus alternate days and as multiple versus single doses in iron-depleted women: two open-label, randomised controlled trials. Lancet Haematol. 2017;4(11):e524-e533.
- World Health Organization. Guideline: Daily iron supplementation in adult women and adolescent girls. Geneva: WHO; 2016.
- Vaucher P, Druais PL, Waldvogel S, Favrat B. Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial. CMAJ. 2012;184(11):1247-1254.
- Burden RJ, Morton K, Richards T, Whyte GP, Pedlar CR. Is iron treatment beneficial in, iron-deficient but non-anaemic (IDNA) endurance athletes? A meta-analysis. Br J Sports Med. 2015;49(21):1389-1397.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. The products discussed on this page are not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare professional before starting any supplement regimen.