Home Ingredients Ferrous Ascorbate (Iron)
Women's Health

Ferrous Ascorbate (Iron)

Evidence Level
Moderate
8 Clinical Trials
5 Documented Benefits
3/5 Evidence Score

Ferrous ascorbate is an iron salt of vitamin C: one iron(II) ion paired with two ascorbate molecules, about 13.8% iron by formula. It is a commonly prescribed iron form in India, usually as tablets labeled 100 mg of iron with folic acid, and as a suspension for children. In randomized trials in pregnant women with low iron it raised hemoglobin about as much as ferrous sulfate, ferrous fumarate and carbonyl iron, and in one trial slightly more than ferrous sulfate after 90 days. In children it raised hemoglobin more than iron polymaltose, colloidal iron and a lower dose of liposomal iron. Stomach complaints and constipation still occur. A pooled analysis found no clear hemoglobin gain from the built-in vitamin C over iron alone. Take iron only if a blood test shows you need it.

Studied Dose 100 mg elemental iron a day, usually with 1.5 mg folic acid, for 1 to 3 months in pregnancy trials; 200 mg a day in one trial; 3 to 6 mg/kg a day in children. These doses exceed the 45 mg/day US adult upper limit and are for low iron confirmed by a blood test.
Active Compound Ferrous ascorbate (iron(II) L-ascorbate, C12H14FeO12, molecular weight 406.08), the iron(II) salt of ascorbic acid; by formula about 13.8% iron. Products are labeled by elemental iron: tablets in the trials gave 100 mg iron with 1.5 mg folic acid, and a suspension was dosed by body weight for children.

Benefits

Hemoglobin and iron stores in pregnant women with low iron

In a four-arm trial of 120 pregnant women with low iron, 200 mg of iron a day as ferrous ascorbate, sulfate, fumarate or carbonyl iron worked equally well. In a 150-woman open-label trial, 100 mg as ferrous ascorbate gave higher hemoglobin at 90 days than 120 mg as ferrous sulfate (11.3 vs 10.99 g/dL), with similar ferritin.

Supported by Trial 2, Trial 1

Hemoglobin compared with other iron forms in children with low iron

In a 125-child trial at equal doses, hemoglobin rose more on ferrous ascorbate than on iron polymaltose (4.88 vs 3.33 g/dL at 3 months). It also beat colloidal iron in a maker-funded trial and a lower dose of liposomal iron in a one-month trial (9.31 vs 8.57 g/dL), though constipation was more common.

Supported by Trial 6, Trial 4

Stomach complaints compared with other iron salts

In a pregnancy trial, side effects affected 42% on ferrous ascorbate and 62% on a higher dose of ferrous sulfate, but only epigastric pain differed significantly. Against gentler or lower-dose forms it fared worse: more constipation than liposomal iron in children, and complaints in 6 of 54 women vs none on SunActive Fe.

Supported by Trial 2, Trial 1

Hemoglobin compared with newer oral forms and iron infusions in pregnancy

In a 4-week trial in 111 pregnant women with low iron, 100 mg of ferrous ascorbate matched 27 mg of SunActive Fe for hemoglobin. In a 73-woman double-blind trial, ferrous asparto glycinate raised hemoglobin and ferritin more, and in 100 women with normal hemoglobin, iron infusions kept hemoglobin and ferritin higher.

Supported by Trial 8, Trial 3

Built-in vitamin C and what trials show it adds

Vitamin C helps the body absorb nonheme iron. Yet in a pooled analysis of studies in people with low hemoglobin, ferrous ascorbate did not raise hemoglobin or ferritin significantly more than iron alone, and in a 440-person trial, adding vitamin C tablets to iron did not speed the hemoglobin rise.

Supported by Trial 2, Trial 3

Mechanism of action

1

Iron supplied in the ferrous form with vitamin C as its partner

Each molecule carries one iron(II) ion and two ascorbate anions. In water it almost fully separates into free ferrous iron and ascorbate by about pH 5, so it is not absorbed as an intact chelate; between pH 6 and 8, ascorbate kept iron more soluble in lab tests, which may help absorption further along the gut.

2

Absorption rises as iron stores fall

In pooled absorption studies of 646 people given a ferrous ascorbate reference dose, absorption was 19% in men with normal iron, 34% in women with normal iron and 67% in people with iron-deficiency anemia, and it fell as ferritin rose. The body takes in more iron from it when stores are low.

3

Vitamin C enhances nonheme iron absorption, with little added effect on repletion

Vitamin C enhances absorption of nonheme iron, which is the rationale for pairing it with iron. In trials that measured hemoglobin and ferritin over weeks, though, iron given with vitamin C or as ferrous ascorbate did not clearly outperform iron alone.

Clinical trials

1
Ferrous Ascorbate vs Ferrous Sulfate, Fumarate and Carbonyl Iron in Pregnancy: Four-Arm RCT
PubMed

Prospective, randomized, open-label, blinded-endpoint trial of four iron salts, each at 200 mg elemental iron a day; primary outcome was the share of women reaching hemoglobin of 11 g/dL or more; funding not described in the abstract (Gamad et al. 2021, J Obstet Gynaecol Res)

120 pregnant women with low hemoglobin from iron deficiency in Chandigarh, India, 30 per group.

All four salts, including ferrous ascorbate, were equally effective for hemoglobin and other blood measures and equally cost-effective. Adverse effects were most common on ferrous fumarate (56.7%). The abstract gives no between-group figures for ferrous ascorbate.

2
Ferrous Ascorbate 100 mg vs Ferrous Sulfate 120 mg vs Iron Polymaltose in Pregnancy: Open-Label RCT
PubMed

Single-center, randomized, open-label 90-day trial: ferrous ascorbate 100 mg iron with 1.5 mg folic acid once daily, ferrous sulfate 60 mg iron twice daily with 5 mg folic acid, or iron polymaltose 100 mg iron once daily; Emcure Pharmaceuticals gifted the ferrous ascorbate and polymaltose products; authors declared no conflicts (Chavan et al. 2021, Indian J Med Res)

177 pregnant women in New Delhi at 12 to 26 weeks with hemoglobin 7 to 9.9 g/dL and ferritin near 9 mcg/L; 150 analyzed.

Hemoglobin at day 90 was 11.3 g/dL on ferrous ascorbate vs 10.99 g/dL on ferrous sulfate (P < 0.05), with no difference at days 30 and 60 and none vs iron polymaltose. Ferritin rose to 31.8, 28.6 and 30.4 mcg/L, not different between groups. Adverse effects affected 42% vs 62% vs 46%; only epigastric pain differed (9 vs 15 women on ferrous sulfate).

3
SunActive Fe 27 mg vs Ferrous Ascorbate 100 mg in Pregnant Women with Low Iron: Open-Label RCT
PubMed

Randomized, open-label, active-controlled, multicenter 4-week trial (CTRI/2024/07/070773). One daily SunActive Fe tablet (27 mg iron with vitamin C, vitamin B12, folic acid and glycine) vs one ferrous ascorbate tablet (100 mg iron with folic acid); primary aim was non-inferiority for hemoglobin change. Material and testing costs were paid by Generex Pharmassist, which employed two co-authors; no Taiyo Kagaku authors (Patki et al. 2025, Sci Rep)

111 second-trimester pregnant women in India aged 20 to 35, hemoglobin 9 to 10.5 g/dL and ferritin below 15 mcg/L; 108 completed.

Hemoglobin rose 2.63 vs 2.62 g/dL (between-group P = 0.973), meeting the non-inferiority margin; ferritin, reticulocyte hemoglobin and FACIT-Fatigue scores (14.1% vs 14.2%) also did not differ. Adverse events occurred in 6 of 54 on ferrous ascorbate and none on SunActive Fe (P = 0.028). The arms differed in iron dose and added vitamins, and the trial was open-label and 4 weeks long.

4
Ferrous Ascorbate vs Polymaltose Complex at 6 mg/kg in Children: 3-Month RCT
PubMed

Randomized controlled trial at a government teaching hospital; both groups received 6 mg/kg elemental iron a day for 3 months; blinding not described in the abstract; authors declared no conflicts (Patil et al. 2019, Indian J Pediatr)

125 children aged 1 to 12 in Aurangabad, India, with clinical signs of anemia from low stores.

Hemoglobin rose more on ferrous ascorbate at 1 month (3.13 vs 2.0 g/dL, P = 0.017) and 3 months (4.88 vs 3.33 g/dL, P = 0.001), with faster early rises in reticulocytes and red cell size. Minor adverse reactions occurred on ferrous ascorbate and none on polymaltose complex.

5
Ferrous Ascorbate vs Colloidal Preparation (Tonoferon) at 3 mg/kg in Children: 12-Week RCT
PubMed

Randomized comparative trial of ferrous ascorbate (Feronia-XT) vs colloidal iron (Tonoferon), each at 3 mg/kg elemental iron a day for 12 weeks; primary outcome was the hemoglobin rise; funded by Zuventus Healthcare, which markets Feronia-XT and employed the second author (Yewale et al. 2013, Indian J Pediatr)

73 children aged 6 months to 12 years in Navi Mumbai, India, diagnosed with anemia from low stores (81 screened).

Hemoglobin rose 3.59 vs 2.43 g/dL (P < 0.01), and 64.86% vs 31.03% of children were no longer anemic at 12 weeks (P < 0.01).

6
Ferrous Ascorbate 3 mg/kg vs Liposomal Ferric Diphosphate 1 mg/kg in Young Children: One-Month RCT
PubMed

Randomized, unblinded trial (CTRI/2024/06/068445) of ferrous ascorbate suspension at 3 mg/kg a day vs liposomal ferric diphosphate suspension at 1 mg/kg a day for one month; no outside funding reported (Rangaraj et al. 2025, Cureus)

98 children aged 6 to 60 months with anemia from low stores in Tamil Nadu, India; 82 analyzed.

After one month hemoglobin was 9.31 vs 8.57 g/dL (P = 0.0018) and serum storage levels 40.9 vs 21.7 mcg/L (P < 0.0001), both higher on ferrous ascorbate. Constipation was more common on ferrous ascorbate (59.5% vs 37.5%, P = 0.046), and adherence and tolerability were poorer. The arms received different doses.

7
Ferrous Asparto Glycinate vs Ferrous Ascorbate in Pregnancy: Double-Blind RCT
PubMed

Double-blind, randomized, multicenter 28-day trial at three Indian centers; doses not given in the abstract; first author from the medical services department of Akumentis Healthcare (Kamdi et al. 2015, J Obstet Gynaecol)

73 pregnant women at 12 to 26 weeks with iron-deficiency anemia.

Hemoglobin and ferritin were significantly higher with ferrous asparto glycinate than with ferrous ascorbate at days 14 and 28. Ferrous ascorbate was the comparator here, and the abstract gives no figures.

8
Oral Ferrous Ascorbate 100 mg vs Intravenous Iron Sucrose in Pregnant Women with Normal Hemoglobin: RCT
PubMed

Randomized controlled trial (CTRI/2024/04/066003) of oral ferrous ascorbate (100 mg elemental iron daily until 32 weeks) vs three 200 mg infusions of iron sucrose; primary outcome was maintenance of hemoglobin; no outside funding reported (Yamini Purna et al. 2025, Cureus)

100 pregnant women in Karnataka, India, with hemoglobin of 11 g/dL or more, 50 per group; 91 analyzed (44 on infusions, 47 on oral iron).

At 12 weeks hemoglobin (11.63 vs 12.19 g/dL) and ferritin (81.28 vs 163.26 ng/mL) were lower on oral ferrous ascorbate than on intravenous iron (P < 0.0001). Nausea (17%) and vomiting (12.8%) occurred only on oral iron; intravenous iron caused rashes, chills and local pain in some women.

Side effects and drug interactions

Common Potential side effects

Digestive complaints occur: in a pregnancy trial 42% on ferrous ascorbate reported effects such as nausea, epigastric pain and constipation, and in young children constipation affected 59.5% on ferrous ascorbate suspension.
The US Tolerable Upper Intake Level for iron is 45 mg a day for adults (40 to 45 mg for infants, children and teens). High doses (45 mg a day or more) may cause nausea and constipation.
People with hereditary hemochromatosis absorb too much iron and are at risk of overload; do not take iron unless a blood test shows you need it.
Accidental overdose of iron-containing products is a leading cause of fatal poisoning in children under 6. Keep iron out of reach of children, and if a child swallows iron, call a doctor or poison control center immediately.

Important Drug interactions

Calcium and dairy: calcium may reduce absorption of both heme and nonheme iron; take calcium and iron supplements at different times.
Tetracycline and quinolone antibiotics: iron binds them and lowers their absorption; follow the antibiotic label on spacing.
Levothyroxine: iron reduces its absorption; labels advise not taking levothyroxine within 4 hours of iron.
Levodopa: iron supplements may reduce how much levodopa the body absorbs.
Proton pump inhibitors: by lowering stomach acid they can reduce iron absorption.
Vitamin C: enhances absorption of nonheme iron.

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Frequently asked questions about Ferrous Ascorbate (Iron)

What is ferrous ascorbate?

It is an iron salt of vitamin C: one iron(II) ion bound to two ascorbate molecules, by formula about 13.8% iron. It is widely prescribed in India, usually as a tablet labeled 100 mg of iron with folic acid, and as a suspension for children. Labels state the elemental iron, which is the number to compare.

Does the vitamin C in it make it work better than other iron?

Not clearly. Vitamin C helps absorption, and some trials found slightly higher hemoglobin than with ferrous sulfate or iron polymaltose, but others found it equal to three other salts. A pooled analysis found no significant hemoglobin or ferritin gain from ferrous ascorbate over iron alone.

Is it easier on the stomach than ferrous sulfate?

Somewhat, in one pregnancy trial: side effects affected 42% vs 62% on a higher dose of ferrous sulfate, though only epigastric pain differed significantly. Nausea, constipation and dark stools still occur, and constipation was more common than with a low-dose liposomal iron in children.

How much iron does it provide, and who should take it?

Trial tablets gave 100 mg of iron a day, more than the 45 mg US adult upper limit, which is why such doses are used to correct low iron under medical care. Take iron only if a blood test shows low iron or a doctor or midwife advises it, keep iron away from children, and if you have hemochromatosis, do not take iron unless your doctor advises it.

What is Ferrous Ascorbate used for?

Ferrous Ascorbate is researched primarily for Women's Health. In a four-arm trial of 120 pregnant women with low iron, 200 mg of iron a day as ferrous ascorbate, sulfate, fumarate or carbonyl iron worked equally well.

Is Ferrous Ascorbate safe, and does it have side effects?

Side effects and cautions reported for Ferrous Ascorbate include: Digestive complaints occur: in a pregnancy trial 42% on ferrous ascorbate reported effects such as nausea, epigastric pain and constipation, and in young children constipation affected 59.5% on ferrous ascorbate suspension. It may also interact with some medications. Ferrous Ascorbate is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Ferrous Ascorbate interact with any medications?

Possible interactions include: Calcium and dairy: calcium may reduce absorption of both heme and nonheme iron; take calcium and iron supplements at different times. Tetracycline and quinolone antibiotics: iron binds them and lowers their absorption; follow the antibiotic label on spacing. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Ferrous Ascorbate?

NutraSmarts rates the evidence for Ferrous Ascorbate as Moderate (3 out of 5). It is backed by 8 study summaries and 16 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(16 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Patki A, Jyothi GS, Thobbi V, Srivastav A, Ganu G, Shah AS. Efficacy and safety of emulsified microsomal ferric pyrophosphate vs. Ferrous Ascorbate in pregnancy with iron-deficiency anemia- a randomized, comparative study. Sci Rep. 2025;15(1):39671. doi: 10.1038/s41598-025-23353-9.PubMedUsed to support: Randomized, open-label, multicenter 4-week trial (CTRI/2024/07/070773) in 111 second-trimester pregnant women in India with hemoglobin 9 to 10.5 g/dL and ferritin below 15 mcg/L (108 completed). One SunActive Fe tablet a day (27 mg iron plus 50 mg vitamin C, 0.75 mcg vitamin B12, 250 mcg folic acid and 10 mg glycine) raised hemoglobin by 2.63 g/dL, against 2.62 g/dL on ferrous ascorbate (100 mg iron with 1.5 mg folic acid); the prespecified non-inferiority margin was met, and ferritin, reticulocyte hemoglobin and FACIT-Fatigue scores (14.1% vs 14.2%) did not differ between groups. Adverse events (nausea, hyperacidity, dark stools) occurred in 6 of 54 women on ferrous ascorbate and none on SunActive Fe (P = 0.028). Material and testing costs were paid by Generex Pharmassist, which employed two co-authors; no Taiyo Kagaku staff were authors.
  2. Gamad N, Saha PK, Sharma P, Suri V, Chakrabarti A, Saha L. A randomized controlled trial comparing the efficacy, tolerability, and cost of oral iron preparations in iron-deficiency anemia in pregnancy. J Obstet Gynaecol Res. 2021;47(11):3828-3841. doi: 10.1111/jog.14999.PubMedUsed to support: Prospective, randomized, open-label, blinded-endpoint trial in 120 pregnant women with iron-deficiency anemia in Chandigarh, India (30 per group): ferrous sulfate, ferrous fumarate, ferrous ascorbate and carbonyl iron, each at 200 mg elemental iron a day. The primary outcome was the share of women reaching hemoglobin of 11 g/dL or more. All four salts were equally effective for hemoglobin and other blood measures and equally cost-effective; adverse effects were most common on ferrous fumarate (56.7%). The authors are from a government teaching institute; funding is not described in the abstract and the full text was not accessible.
  3. Chavan S, Rana P, Tripathi R, Tekur U. Comparison of efficacy & safety of iron polymaltose complex & ferrous ascorbate with ferrous sulphate in pregnant women with iron-deficiency anaemia. Indian J Med Res. 2021;154(1):78-84. doi: 10.4103/ijmr.IJMR_1753_18.PubMedUsed to support: Single-center, randomized, open-label trial in New Delhi (2014 to 2015) in pregnant women at 12 to 26 weeks with hemoglobin 7 to 9.9 g/dL: ferrous sulfate 60 mg iron twice daily plus 5 mg folic acid, iron polymaltose 100 mg iron with 0.55 mg folic acid, or ferrous ascorbate 100 mg iron with 1.5 mg folic acid (Ferium XT) once daily for 90 days; 177 randomized, 150 analyzed. At day 90 hemoglobin was 11.3 g/dL on ferrous ascorbate vs 10.99 g/dL on ferrous sulfate (P < 0.05), with no difference vs iron polymaltose and no difference at days 30 and 60; ferritin rose from about 8.7 to 31.8 mcg/L, not different between groups. Adverse effects: 42% on ferrous ascorbate vs 62% on ferrous sulfate, a significant difference only for epigastric pain (9 vs 15 women). Emcure Pharmaceuticals gifted the ferrous ascorbate and polymaltose products; the authors declared no conflicts.
  4. Patil P, Geevarghese P, Khaire P, Joshi T, Suryawanshi A, Mundada S, Pawar S, Farookh A. Comparison of Therapeutic Efficacy of Ferrous Ascorbate and Iron Polymaltose Complex in Iron Deficiency Anemia in Children: A Randomized Controlled Trial. Indian J Pediatr. 2019;86(12):1112-1117. doi: 10.1007/s12098-019-03068-2.PubMedUsed to support: Randomized trial at a government hospital in Aurangabad, India, in 125 children aged 1 to 12 with signs of iron-deficiency anemia: ferrous ascorbate or iron polymaltose complex at 6 mg/kg elemental iron a day for 3 months. Hemoglobin rose more with ferrous ascorbate at 1 month (3.13 vs 2.0 g/dL, P = 0.017) and 3 months (4.88 vs 3.33 g/dL, P = 0.001), with larger early rises in MCV and reticulocytes. Minor adverse reactions occurred on ferrous ascorbate and none on iron polymaltose. The authors declared no conflicts; blinding is not described in the abstract.
  5. Yewale VN, Dewan B. Treatment of iron deficiency anemia in children: a comparative study of ferrous ascorbate and colloidal iron. Indian J Pediatr. 2013;80(5):385-90. doi: 10.1007/s12098-012-0906-6.PubMedUsed to support: Randomized trial in Navi Mumbai, India, in children aged 6 months to 12 years with iron-deficiency anemia (81 screened, 73 included): ferrous ascorbate (Feronia-XT) or colloidal iron (Tonoferon), each at 3 mg/kg elemental iron a day for 12 weeks; the primary outcome was the rise in hemoglobin. Hemoglobin rose more on ferrous ascorbate (3.59 vs 2.43 g/dL, P < 0.01), and more children were no longer anemic (64.86% vs 31.03%). Zuventus Healthcare, which markets Feronia-XT, is listed as the funder, and the second author works in its medical services department (per the publisher's article page).
  6. Rangaraj S, Suresh P, Sundar S, Raju P. Liposomal Iron vs. Conventional Iron in the Treatment of Iron Deficiency Anemia in Children: A Randomized Controlled Trial. Cureus. 2025;17(11):e97183. doi: 10.7759/cureus.97183.PubMedUsed to support: Randomized, unblinded trial (CTRI/2024/06/068445) at a medical college hospital in Tamil Nadu, India, in 98 children aged 6 to 60 months with iron-deficiency anemia: liposomal ferric diphosphate suspension at 1 mg/kg a day vs ferrous ascorbate suspension at 3 mg/kg a day for one month (82 analyzed). Hemoglobin was 9.31 vs 8.57 g/dL and ferritin 40.9 vs 21.7 mcg/L after one month, both higher on ferrous ascorbate (P = 0.0018 and P < 0.0001). Constipation was more common on ferrous ascorbate (59.5% vs 37.5%, P = 0.046), and adherence and oral tolerability were poorer; diarrhea did not differ. The arms received different iron doses. The authors reported no outside funding.
  7. Kamdi SP, Palkar PJ. Efficacy and safety of ferrous asparto glycinate in the management of iron deficiency anaemia in pregnant women. J Obstet Gynaecol. 2015;35(1):4-8. doi: 10.3109/01443615.2014.930098.PubMedUsed to support: Double-blind, randomized, multicenter trial at three centers in India in 73 pregnant women at 12 to 26 weeks with iron-deficiency anemia: ferrous asparto glycinate vs ferrous ascorbate for 28 days. Hemoglobin and ferritin were significantly higher with ferrous asparto glycinate at days 14 and 28. Doses are not given in the abstract. The first author works in the medical services department of Akumentis Healthcare, an Indian drug company.
  8. Yamini Purna M, Patil N, Yaliwal RG, Biradar A, Shiragur S. A Randomized Controlled Trial to Compare the Role of Intravenous Iron Sucrose Versus Oral Ferrous Ascorbate for the Prophylaxis of Anemia in Pregnant Women. Cureus. 2025;17(4):e82941. doi: 10.7759/cureus.82941.PubMedUsed to support: Randomized trial at a medical college hospital in Karnataka, India, in 100 pregnant women with hemoglobin of 11 g/dL or more: intravenous iron sucrose 200 mg at 20 to 24, 24 to 28 and 28 to 32 weeks vs oral ferrous ascorbate providing 100 mg elemental iron daily until 32 weeks; the primary outcome was maintenance of hemoglobin. Of 100 randomized, 91 were analyzed (44 and 47). At 12 weeks hemoglobin (12.19 vs 11.63 g/dL) and ferritin (163.26 vs 81.28 ng/mL) were higher with intravenous iron (P < 0.0001). Nausea (17%), vomiting (12.8%) and other digestive effects occurred on oral iron, none on intravenous iron, which caused rashes, chills and local pain in some women. No outside funding was reported.
  9. Loganathan V, Bharathi A, Prince AM, Ramakrishnan J. Treatment efficacy of vitamin C or ascorbate given as co-intervention with iron for anemia - A systematic review and meta-analysis of experimental studies. Clin Nutr ESPEN. 2023;57:459-468. doi: 10.1016/j.clnesp.2023.07.081.PubMedUsed to support: Systematic review and meta-analysis (PROSPERO CRD42022306612) of experimental studies in people with confirmed anemia comparing oral vitamin C or ascorbate given with iron against iron alone; 9 studies reviewed, 7 (905 participants) pooled. For ferrous ascorbate as the intervention, the differences in hemoglobin (SMD 0.44, 95% CI -0.30 to 1.26) and ferritin (SMD 0.03, 95% CI -0.68 to 0.73) were not statistically significant, and for iron plus a separate vitamin C supplement the hemoglobin difference (SMD 0.11, 95% CI -0.05 to 0.28) was also not significant; its ferritin estimate (SMD -0.90, 95% CI -1.09 to -0.72) favored iron alone, although the abstract describes it as not significant. The authors rated the methodological quality of the evidence very low.
  10. Li N, Zhao G, Wu W, Zhang M, Liu W, Chen Q, Wang X. The Efficacy and Safety of Vitamin C for Iron Supplementation in Adult Patients With Iron Deficiency Anemia: A Randomized Clinical Trial. JAMA Netw Open. 2020;3(11):e2023644. doi: 10.1001/jamanetworkopen.2020.23644.PubMedUsed to support: Single-center, open-label equivalence trial (NCT02631668) in 440 adults in China with newly diagnosed iron-deficiency anemia (96.8% women): a 100 mg oral iron tablet with or without 200 mg vitamin C every 8 hours for 3 months. The hemoglobin rise at 2 weeks was 2.00 vs 1.84 g/dL (difference 0.16 g/dL, 95% CI -0.03 to 0.35), meeting equivalence, and the ferritin rise at 8 weeks (35.75 vs 34.48 ng/mL) and adverse events (20.9% vs 20.5%) did not differ. It tested a separate vitamin C tablet, not ferrous ascorbate.
  11. Valenzuela C, Olivares M, Brito A, Hamilton-West C, Pizarro F. Is a 40 % absorption of iron from a ferrous ascorbate reference dose appropriate to assess iron absorption independent of iron status? Biol Trace Elem Res. 2013;155(3):322-6. doi: 10.1007/s12011-013-9797-2.PubMedUsed to support: Pooled analysis of 646 participants (582 women, 64 men) from iron absorption studies by a University of Chile group that used a ferrous ascorbate reference dose. Absorption of the reference dose was 19% in men with normal iron status, 34% in women with normal status, 40% in women with depleted stores, 43% in iron deficiency without anemia and 67% in iron-deficiency anemia; serum ferritin correlated inversely with absorption (r = -0.41). It measured absorption of a reference dose, not supplementation outcomes.
  12. Plug CM, Dekker D, Bult A. Complex stability of ferrous ascorbate in aqueous solution and its significance for iron absorption. Pharm Weekbl Sci. 1984;6(6):245-8. doi: 10.1007/BF01954553.PubMedUsed to support: Laboratory chemistry study of ferrous ascorbate in water. It found that ferrous ascorbate is almost completely dissociated into ferrous iron and ascorbate at about pH 5, so chelate formation does not contribute significantly to iron absorption, while between pH 6 and 8 ascorbate kept iron more soluble, which may be relevant to absorption. It notes that greater absorption from ferrous ascorbate than ferrous sulfate in the body had been attributed to ascorbate slowing iron oxidation and to chelation. Laboratory data, not human evidence.
  13. National Center for Biotechnology Information. PubChem Compound Summary for CID 86763295, Ferrous ascorbate. PubChem, National Library of Medicine. 2026;Compound record CID 86763295, accessed November 2026..SourceUsed to support: Not PubMed-indexed (NIH chemical database, read 2026). Lists ferrous ascorbate (iron(II) L-ascorbate; CAS 24808-52-4) with the molecular formula C12H14FeO12 and a molecular weight of 406.08, that is, one iron(II) ion with two ascorbate anions. From this formula iron makes up about 13.8% of the compound's weight (55.85 of 406.08).
  14. NIH Office of Dietary Supplements. Iron: Fact Sheet for Health Professionals. National Institutes of Health. 2025;Online fact sheet, updated September 4, 2025..SourceUsed to support: Not PubMed-indexed (official NIH fact sheet; read via a 2026 web archive copy because the live site blocked automated access). States the Tolerable Upper Intake Level for iron is 45 mg for adults and 40 to 45 mg for infants, children and adolescents; that supplemental iron at 45 mg/day or more may cause nausea and constipation; that experts suggest taking calcium and iron supplements at different times; that vitamin C enhances nonheme iron bioavailability; that people with hereditary hemochromatosis are at risk of iron overload; that iron supplements may interact with levodopa and levothyroxine (labels advise against taking levothyroxine within 4 hours of iron) and that proton pump inhibitors can reduce iron absorption; and quotes the required US warning that accidental overdose of iron-containing products is a leading cause of fatal poisoning in children under 6.
  15. MedlinePlus, National Library of Medicine. Ciprofloxacin: MedlinePlus Drug Information. MedlinePlus. 2026;Online drug information page, last revised August 15, 2026..SourceUsed to support: Not PubMed-indexed (official NIH National Library of Medicine drug information, read 2026). Advises that antacids or multivitamins containing calcium, magnesium hydroxide, aluminum hydroxide, zinc or iron be taken at least 6 hours before or 2 hours after ciprofloxacin.
  16. Chartwell RX, LLC. Doxycycline hyclate tablets, capsules and powder for suspension: prescribing information (DailyMed). DailyMed, National Library of Medicine. 2026;Structured product label, set ID 3e7cf78f-3b48-4614-9fa4-c6d1e0c05a35, published October 19, 2026..SourceUsed to support: Not PubMed-indexed (US drug label, read 2026). States that absorption of tetracyclines is impaired by antacids containing aluminum, calcium or magnesium and by iron-containing preparations.