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What iron does
Most of the body's iron sits in haemoglobin, the protein in red blood cells that carries oxygen from the lungs to every tissue. Smaller amounts go into myoglobin in muscle and into the enzymes mitochondria use to make energy. What isn't in use is stored as ferritin, mainly in the liver. [1]
Iron deficiency happens in stages. Stores run down first: ferritin falls, but haemoglobin is still normal. You can already feel tired at this point. Only when stores are empty does haemoglobin drop, and that is iron deficiency anaemia. This is why a "normal" haemoglobin result does not rule out low iron, and why ferritin is the more useful number. [1]
The body has no active way to excrete iron. It controls how much it holds almost entirely by controlling how much it absorbs. The hormone that does this, hepcidin, explains most of the dosing advice on this page. [1]
Test before you take it
Not all anaemia is iron deficiency
In India, anaemia can also come from vitamin B12 or folate deficiency (common in vegetarians), from thalassaemia trait (which makes red cells small, just like iron deficiency, but isn't fixed by iron), or from chronic disease. Taking iron for anaemia that isn't caused by low iron does nothing for it and adds iron you don't need. A CBC plus serum ferritin is an inexpensive test at most labs, and it tells you whether iron is the answer. [1]
How to read the ferritin number:
- Below 15 µg/L: iron deficiency in an otherwise healthy adult, per the WHO. [2]
- Below 70 µg/L with infection or inflammation: ferritin rises during inflammation, so the WHO sets a higher cut-off when it's present. [2]
- 15–50 µg/L with unexplained tiredness: a grey zone. In the Vaucher trial, women with ferritin under 50 µg/L and normal haemoglobin had less fatigue on iron than on placebo. [3]
How iron absorption works — and why daily dosing backfires
Iron from plants and supplements (non-haem iron) is absorbed in the upper small intestine. It crosses into the blood through a single exit channel, ferroportin. Hepcidin, made by the liver, shuts ferroportin down. When iron levels rise, hepcidin rises and absorption falls. [1]
A supplement triggers this system itself. Moretti and colleagues showed that a dose of 60 mg or more raises hepcidin for up to 24 hours, so the next morning's dose is absorbed less well. Splitting the dose twice a day made the rise in hepcidin bigger. [4] Stoffel and colleagues then tested schedules directly. Alternate-day dosing gave higher total absorption than daily dosing, and one morning dose absorbed as well as the same amount split in two. [5] A follow-up in women who were already anaemic found the same result at 100 mg and 200 mg doses, with a trend toward fewer stomach side effects. [6]
Clinical evidence — what the trials show
| Study | Form / dose | Duration | n | Key finding | Grade |
|---|---|---|---|---|---|
| Moretti et al. (2015) — Blood doi:10.1182/blood-2015-05-642223 |
Ferrous sulphate 40–240 mg, isotope-labelled | Short-term absorption studies | Iron-depleted young women | Doses of 60 mg or more raised hepcidin for up to 24 h and lowered absorption from the next day's dose. Twice-daily dosing raised hepcidin more than once-daily. This is the mechanism behind alternate-day dosing. | B |
| Stoffel et al. (2017) — Lancet Haematol doi:10.1016/S2352-3026(17)30182-5 |
Ferrous sulphate 60 mg; daily vs alternate day; single vs split dose | 14 days vs 28 days | Two RCTs, iron-depleted women | Total fractional absorption 21.8% on alternate days vs 16.3% on consecutive days. One morning dose absorbed as well as the same amount split twice daily. | A |
| Stoffel et al. (2020) — Haematologica doi:10.3324/haematol.2019.220830 |
Ferrous sulphate 100 mg and 200 mg | Crossover | Women with iron deficiency anaemia | The alternate-day advantage held in women who were already anaemic, not just depleted. There was a trend toward fewer GI side effects on alternate days. | B |
| Tolkien et al. (2015) — PLoS One doi:10.1371/journal.pone.0117383 |
Ferrous sulphate vs placebo or IV iron | Meta-analysis | 43 trials, 6,831 adults | Ferrous sulphate more than doubled the odds of GI side effects vs placebo (OR 2.32) and tripled them vs IV iron (OR 3.05). The review found no clear link to dose. | A |
| Fischer et al. (2023) — Nutr Rev doi:10.1093/nutrit/nuac106 |
Ferrous bisglycinate vs other iron salts | 4–20 weeks | 17 RCTs | In pregnant women (9 trials): +0.54 g/dL haemoglobin and 64% fewer GI adverse events with bisglycinate. In children (4 trials): no difference. There isn't enough data in non-pregnant adults to call it. | A |
| Vaucher et al. (2012) — CMAJ doi:10.1503/cmaj.110950 |
80 mg/day prolonged-release ferrous sulphate vs placebo | 12 weeks | 198 | In menstruating women with unexplained fatigue, ferritin under 50 µg/L and normal haemoglobin, fatigue fell 47.7% on iron vs 28.8% on placebo. Haemoglobin and ferritin rose by week 6. | A |
| Li et al. (2020) — JAMA Netw Open doi:10.1001/jamanetworkopen.2020.23644 |
100 mg iron ± 200 mg vitamin C, every 8 h | 2-week primary endpoint | 440 | Haemoglobin rose 2.00 g/dL with vitamin C vs 1.84 g/dL without after 2 weeks, which met the trial's test for equivalence. A separate vitamin C pill added nothing meaningful. | B |
The overall picture: iron corrects iron deficiency, and that is not in question. [1] Most of the recent research is about getting more of each dose absorbed with fewer side effects, because side effects are the main reason people stop taking it. [7]
Dosage and timing
Evidence-based protocol
Diagnosed iron deficiency (with or without anaemia): 60–120 mg elemental iron as one morning dose, on alternate days, for at least 3 months. Recheck haemoglobin and ferritin at 6–8 weeks. [5][6] Low ferritin with fatigue, normal haemoglobin: about 80 mg elemental iron, the dose used in the Vaucher trial, with bloods rechecked at 6 weeks. [3] Prevention in menstruating women: the government's Anaemia Mukt Bharat programme uses one 60 mg iron + 500 mcg folic acid tablet weekly. [8] Pregnancy: follow your obstetrician. The national protocol is 60 mg daily from the fourth month for at least 180 days. [8]
The chai rule
Polyphenols in tea and coffee bind non-haem iron in the gut. Black tea drunk with a meal cut iron absorption by 79–94% in Hurrell's absorption studies, and coffee and cocoa had similar effects. [9] Taking the iron tablet with morning chai throws most of it away. Take it at least an hour before tea or coffee. Keep it apart from calcium supplements and antacids too, and ask your pharmacist about spacing it from thyroid medicine and antibiotics such as tetracyclines and fluoroquinolones. (Our chai and caffeine research covers the other side of your tea habit.)
Empty stomach or with food?
An empty stomach absorbs best, and that is also when stomach side effects are worst. If the tablet makes you nauseous, taking it with a light, low-tea, low-calcium breakfast is fine. Absorbing somewhat less beats stopping altogether. Switching to alternate days or to bisglycinate are the other two ways to make it easier on the stomach. [6][7]
Vitamin C: food yes, pill probably not
Vitamin C makes iron from a single meal much easier to absorb. Across a whole diet, though, the effect is far smaller than single-meal studies suggest. [10] And in the 440-patient Li trial, adding a 200 mg vitamin C pill to the iron tablet made no meaningful difference to haemoglobin. [11] Don't pay extra for "iron + vitamin C" combinations. Lemon on your dal, or guava or amla with meals, is enough.
Which form to buy
Ferric forms (ferric pyrophosphate, iron polymaltose, "carbonyl iron") and "plant-based" or curry-leaf iron extracts all appear on Indian shelves. The ferrous salts above have far more trial evidence behind them. If a label hides the form or the elemental iron amount, treat that as the answer. Monthly prices above assume one tablet a day, based on the products in the table below.
India-specific context
Why iron is India's most important supplement
The vegetarian plate problem
Most Indian dietary iron comes from cereals, pulses and greens. That is non-haem iron, absorbed far less efficiently than the haem iron in meat. Phytate in whole grains and dal, and polyphenols in tea, reduce it further. [12][9] On paper, a vegetarian diet can meet the iron RDA. In practice, much of that iron is never absorbed. Isotope studies put absorption at 5–12% for vegetarian diets vs 14–18% for mixed diets, and ICMR's RDA allows for this. [13] Soaking, sprouting and fermenting (idli, dosa, dhokla) break down some of the phytate. So does eating a vitamin C source at the same meal.
Who should be tested
Any woman who menstruates heavily, anyone pregnant or planning to be, vegetarians with unexplained tiredness, breathlessness on stairs, brittle nails or hair shedding, frequent blood donors, and endurance athletes. Also test before "just starting a multivitamin with iron": if you have thalassaemia trait, extra iron won't help your anaemia. Our guide to iron deficiency in Indian women covers symptoms and testing in more depth.
Reading the label
Three checks, in this order:
- Elemental iron in mg. "Ferrous sulphate 200 mg" is not 200 mg of iron. It's roughly 40–65 mg depending on the hydrate. Good labels state the elemental figure separately.
- The exact salt. "Iron", "chelated iron" or "iron complex" without naming the compound means you can't judge it. This matters: our HK Vitals re-score documents a product that quietly switched from bisglycinate to sulphate with the same front label.
- What it's combined with. Folic acid and B12 are sensible partners. Large amounts of calcium in the same tablet work against the iron.
Indian brand comparison
| Brand & product | Price | Form | Score | Our take |
|---|---|---|---|---|
| Govt IFA "red tablet" (Anaemia Mukt Bharat) | Free | Ferrous sulphate 60 mg + folic acid 500 mcg | — | The right dose, free at PHCs and anganwadis. Works as well as anything on this list if you tolerate sulphate. Start here if cost matters. |
| Purayati Iron + Folic Acid + B12 | ₹549 / 60ct | Ferrous bisglycinate · methylfolate · methylcobalamin | 7.7 (B) | Active forms of all three. The best-formulated combination for Indian women with iron-deficiency anaemia. Top pick. |
| Swisse Ultiboost Iron | ₹1,199 / 30ct | Ferrous bisglycinate 25 mg | 7.3 (B) | Correct form, import pricing. You're paying for the brand, not better iron. |
| Himalayan Organics Iron Bisglycinate 25 mg | ₹449 / 90ct | Ferrous bisglycinate 25 mg | 7.1 (B) | Correct form at the lowest cost per dose for bisglycinate. No COA published. Best value. |
| Oziva Plant-Based Iron + Vitamin C | ₹899 / 30 days | Ferric pyrophosphate + vitamin C | 6.7 (C) | Gentle, but a less-studied form, a vitamin C add-on that trials say is unnecessary, and no COA. |
| HK Vitals Iron Folic Acid B12 | ₹299 / 60ct | Ferrous fumarate · cyanocobalamin | 6.4 (C) | Functionally adequate. Fumarate works; the B12 form is the cheaper one. |
| HK Vitals Iron + Folic Acid (capsule) | ₹249 / 60ct | Switched to ferrous sulphate (Apr 2026) | 6.1 | Silent reformulation from bisglycinate. Sulphate isn't bad; hiding the change is. Full re-score → |
| Baidyanath Punarnava Mandur | ₹249 / 80ct | Classical iron-herb preparation | 5.8 (D) | Traditional use, few modern trials, and possible heavy metals in classical preparations. Not a substitute for tested iron. |
Scores and prices come from our product database (2026). Prices change; check the listing before buying. Full rankings: vitamins & minerals compared.
Safety
Stomach upset and constipation
The main reason people stop. Ferrous sulphate more than doubles the odds of GI side effects vs placebo. [7] Fix it in this order: alternate days, then take with food, then switch to bisglycinate. Black stools are normal on iron and not a sign of bleeding by themselves.
Keep it away from children
Iron tablets are a leading cause of fatal poisoning in young children, and sugar-coated red tablets look like sweets. Store them locked and out of reach.
45 mg/day without supervision
The tolerable upper limit for adults is 45 mg/day of elemental iron, set on GI side effects. [14] Treatment doses above this are normal, but they're for diagnosed deficiency with follow-up bloods, not for "energy".
Thalassaemia, haemochromatosis, gut disease
People with thalassaemia (not just the trait), haemochromatosis or repeated transfusions can build up dangerous iron overload. Inflammatory bowel disease, and anaemia that doesn't respond to oral iron, need a doctor. So does unexplained iron deficiency in men or in women after menopause, because it can signal hidden bleeding. [1]
Commonly taken together
Folic acid + Vitamin B12
High synergyRed-cell production needs all three. Anaemia in Indian vegetarians can be mixed, iron plus B12. Folic acid comes with iron in every government IFA tablet for this reason. See our B12 deep-dive.
Vitamin C (from food)
Moderate synergyImproves iron absorption from meals, especially plant meals. It doesn't need to be a pill: the Li trial found no extra haemoglobin gain from adding 200 mg vitamin C to iron tablets. [11]
Vitamin D3
Moderate synergyNo direct interaction with iron. The same people, mostly Indian women indoors most of the day, are often low in both, so it's worth testing both at once. See our vitamin D3 deep-dive.
Calcium, tea, coffee
Keep apartNot partners. They reduce iron absorption when taken at the same time. Take calcium at night and iron in the morning, with at least an hour between iron and chai. [9]
Scoring rubric — full breakdown
1. Evidence quality
That iron corrects iron deficiency is settled, and dosing schedules are now tested with isotope-labelled absorption trials. The Vaucher RCT extends the benefit to non-anaemic women with low ferritin. We deduct because the advantage of bisglycinate is shown clearly only in pregnancy, and most absorption trials are small. [5][15]
2. Dosage confidence
The dose range is clear, ferritin gives a measurable target, and the hepcidin work explains why timing matters. We deduct because the best total dose for alternate-day regimens over months, rather than absorption in the short term, is still being studied. [4][6]
3. India market fit
Anaemia affects 57% of Indian women, and the diet is mostly vegetarian, drunk with chai, and hard to absorb iron from. A free government tablet makes iron accessible to everyone. No other supplement is as clearly needed in India. [8][13]
4. Safety profile
Safe at the right dose for people who are actually deficient. The score reflects real downsides: GI side effects that cause many people to stop, overdose risk in children, overload risk in people with thalassaemia or haemochromatosis, and the risk of treating anaemia that isn't iron deficiency. [7][14]
5. Label accuracy (tested products)
Too many Indian iron products give the compound weight instead of elemental iron, don't name the salt, or change it without notice (see the HK Vitals case). Few brands publish COAs. The government IFA tablet is clearly labelled.
Frequently asked questions
Should I take iron every day or every other day?
A dose of 60 mg or more raises the iron-regulating hormone hepcidin for about 24 hours, which cuts absorption from the next day's dose. In iron-depleted women, taking iron on alternate days gave higher total absorption than daily dosing (21.8% vs 16.3% fractional absorption in Stoffel 2017). For someone who is not in a hurry, one morning dose on alternate days absorbs better and usually causes fewer stomach problems. If a doctor is correcting severe anaemia or you are pregnant, follow their schedule.
Is ferrous bisglycinate better than ferrous sulphate?
It is gentler, and in pregnancy it performs better. A 2023 meta-analysis of 17 trials found bisglycinate raised haemoglobin more (+0.54 g/dL) and caused about 64% fewer stomach side effects than other iron salts in pregnant women. In children there was no difference. Ferrous sulphate still works and is what the free government IFA tablet uses; bisglycinate is worth paying for if sulphate upsets your stomach.
Does chai stop iron absorption?
Yes, strongly. In a classic absorption study, black tea taken with a meal cut non-haem iron absorption by 79–94%. Take your iron at least an hour away from tea and coffee.
Do I need vitamin C with my iron tablet?
Probably not as a separate pill. In a 440-patient randomised trial, adding 200 mg vitamin C to oral iron gave the same haemoglobin rise as iron alone. Vitamin C-rich food does help iron absorption from meals, so a squeeze of lemon on dal or an amla is still sensible.
What ferritin level means I am iron deficient?
The WHO uses serum ferritin below 15 µg/L for iron deficiency in healthy adults, and below 70 µg/L when infection or inflammation is present. Many clinicians treat symptomatic women below 30–50 µg/L; the Vaucher trial showed less fatigue with iron in non-anaemic women with ferritin under 50 µg/L.
How much iron should I take?
ICMR-NIN 2020 sets the dietary RDA at 19 mg/day for men and 29 mg/day for women. For treating diagnosed deficiency, trials use 60–120 mg elemental iron per dose. The adult upper limit for routine intake without medical supervision is 45 mg/day. Get haemoglobin and ferritin tested before taking high-dose iron, and recheck after 6–8 weeks.
References
- 1Pasricha SR, Tye-Din J, Muckenthaler MU, Swinkels DW. Iron deficiency. Lancet. 2021;397(10270):233–48.doi:10.1016/S0140-6736(20)32594-0
- 2World Health Organization. WHO guideline on use of ferritin concentrations to assess iron status in individuals and populations. Geneva: WHO; 2020. NCBI Bookshelf
- 3Vaucher 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):1247–54.doi:10.1503/cmaj.110950
- 4Moretti D, Goede JS, Zeder C, et al. Oral iron supplements increase hepcidin and decrease iron absorption from daily or twice-daily doses in iron-depleted young women. Blood. 2015;126(17):1981–9.doi:10.1182/blood-2015-05-642223
- 5Stoffel NU, Cercamondi CI, Brittenham G, et al. Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split dosing in iron-depleted women: two open-label, randomised controlled trials. Lancet Haematol. 2017;4(11):e524–33.doi:10.1016/S2352-3026(17)30182-5
- 6Stoffel NU, Zeder C, Brittenham GM, Moretti D, Zimmermann MB. Iron absorption from supplements is greater with alternate day than with consecutive day dosing in iron-deficient anemic women. Haematologica. 2020;105(5):1232–9.doi:10.3324/haematol.2019.220830
- 7Tolkien Z, 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.doi:10.1371/journal.pone.0117383
- 8Ministry of Health and Family Welfare, Government of India. Anemia Mukt Bharat: Intensified National Iron Plus Initiative — Operational Guidelines. 2018. nhm.gov.in. Prevalence figures: International Institute for Population Sciences. National Family Health Survey (NFHS-5), 2019–21: India Report. Mumbai: IIPS; 2021. dhsprogram.com
- 9Hurrell RF, Reddy M, Cook JD. Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. Br J Nutr. 1999;81(4):289–95.doi:10.1017/S0007114599000537
- 10Cook JD, Reddy MB. Effect of ascorbic acid intake on nonheme-iron absorption from a complete diet. Am J Clin Nutr. 2001;73(1):93–8.doi:10.1093/ajcn/73.1.93
- 11Li N, et al. 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
- 12Hurrell R, Egli I. Iron bioavailability and dietary reference values. Am J Clin Nutr. 2010;91(5):1461S–7S.doi:10.3945/ajcn.2010.28674F
- 13ICMR–National Institute of Nutrition. Nutrient Requirements for Indians: Recommended Dietary Allowances and Estimated Average Requirements. Hyderabad: ICMR-NIN; 2020.
- 14Institute of Medicine (US) Panel on Micronutrients. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington DC: National Academies Press; 2001.doi:10.17226/10026
- 15Fischer JAJ, Cherian AM, Bone JN, Karakochuk CD. The effects of oral ferrous bisglycinate supplementation on hemoglobin and ferritin concentrations in adults and children: a systematic review and meta-analysis of randomized controlled trials. Nutr Rev. 2023;81(8):904–20.doi:10.1093/nutrit/nuac106
Medical note. This page is educational and not a diagnosis. Iron deficiency has causes, such as bleeding or malabsorption, that a supplement will hide rather than fix. Get tested and talk to a doctor before taking treatment doses, and always during pregnancy.
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