Mechanism of Action
Iron operates at multiple levels of cellular metabolism. Within mitochondria (the cell's energy powerhouses), it forms the catalytic core of electron transport chain complexes. Without iron, ATP production (the universal energy molecule) collapses.
Iron is also the central component of haemoglobin, the red blood cell protein that captures oxygen in the lungs and delivers it to tissues. Myoglobin, its muscular counterpart, serves a comparable role as an oxygen reserve within muscle fibres.
Beyond oxygen transport, iron participates in DNA synthesis and cell division. It also contributes to the production of neurotransmitters such as dopamine and serotonin, as well as to the normal function of the immune system.
The downside of this reactivity: free iron (not bound to a transport protein) can react with hydrogen peroxide to generate hydroxyl radicals. These reactive species damage DNA, membrane lipids, and proteins. The body sequesters iron in ferritin and transferrin to contain this threat. This control weakens when stores exceed storage capacity.
Key Benefits
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Blood that carries oxygen more effectively: iron contributes to normal formation of red blood cells and haemoglobin, as well as to normal oxygen transport in the body. A Cochrane synthesis of 51 trials and 6,861 menstruating women measures higher haemoglobin at the end of intervention, and less frequent low stores.
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Less day-to-day tiredness: iron contributes to the reduction of tiredness and fatigue. That contribution follows directly from its role in oxygen transport and in cellular energy production, two functions that low stores slow down.
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Energy available for exertion: iron contributes to normal energy-yielding metabolism. Muscles depend on it twice over, for the oxygen they receive and for the energy they draw from it.
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Sustained thinking: iron contributes to normal cognitive function. The brain uses a large share of the oxygen the blood delivers, and it relies on iron to build several of its chemical messengers.
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Better-supported immune defences: iron contributes to the normal function of the immune system. Defence cells multiply quickly when called upon, and that rapid multiplication requires iron.
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Tissues that keep renewing: iron has a role in the process of cell division, a fundamental mechanism for replacing cells and maintaining biological integrity over time.
Dosage & Forms
The iron forms available for supplementation fall into three categories. Inorganic salts (sulphate, fumarate, gluconate) offer a high cost-effectiveness ratio but frequently cause digestive discomfort. Encapsulated forms, such as liposomal ferric pyrophosphate, aim to improve tolerance at a higher technological cost. Amino acid chelates, including ferrous bisglycinate, maintained iron status at a lower elemental dose than iron salts in two randomised trials.
The European nutrient reference value is 14 milligrams per day, and the maximum daily amount permitted in food supplements in France is 21 milligrams of elemental iron. Intervention trials work higher: 40 to 80 milligrams to preserve stores during pregnancy, 80 milligrams in the fatigue trials.
Timing matters as much as quantity. A trial published in The Lancet Haematology measured higher fractional absorption with a single morning dose every other day than with closely spaced daily doses.
In the Singular Formula
Inclusion rationale
Iron contributes to normal formation of red blood cells and haemoglobin, to normal oxygen transport in the body and to the reduction of tiredness and fatigue. Included only according to your profile. Iron is a double-edged element: indispensable for oxygen transport and cellular respiration, but potentially pro-oxidant in excess via the Fenton reaction. This is why its supplementation is personalized and not systematic in the formula. Vitamin C (present in the formula) increases non-heme iron absorption by keeping it in reduced form (Fe2+) in the intestinal tract. The balance with zinc and copper (also present in the formula in bisglycinate form) is carefully calibrated to avoid mineral absorption competition. Two randomised trials in pregnant women, over three to five months, compared iron bisglycinate with ferrous sulphate: at 15 then 25 mg of iron against 40 and 50 mg, it maintained iron status with fewer digestive complaints. The dose is calibrated on ferritin, transferrin saturation and haemoglobin, three markers re-read at every blood panel.
Selected form
PHARMAGNESIA® FBg A is a fully reacted ferrous bisglycinate hydrochloride containing 17 to 22% elemental iron and no added excipient. Each iron atom (Fe2+) is bonded to two glycine molecules, which form the chelate's intrinsic ligand. Iron contributes to the reduction of tiredness and fatigue, and to normal oxygen transport in the body.
Formula dosage
0 to 21 mg.
Dose expressed as active substance, excluding excipients and carriers of the raw material.
Synergies in the formula
Safety & Precautions
Ferrous bisglycinate is well tolerated at standard doses. In two randomised trials in pregnant women, it produced dark stools in 8% of participants, against 22 to 31% under ferrous fumarate or sulphate.
Iron supplementation is not recommended without prior assessment of iron status. Excess iron accumulates in organs and promotes oxidative stress. Individuals with haemochromatosis, who absorb iron in excess, should not supplement without specialist supervision. A 2024 European opinion sets a safe level of intake of 40 milligrams per day in adults, including pregnant and lactating women.
Iron absorption is reduced by calcium, tea, coffee, and phytates, found in whole grains and legumes. Vitamin C, conversely, enhances its absorption. A two-hour interval between iron intake and calcium or zinc is recommended to limit absorption competition.
Pregnant or breastfeeding women, as well as individuals taking medication, are advised to consult a healthcare professional before any iron supplementation.
Scientific Studies
| Authors | Year | Type | Journal | |
|---|---|---|---|---|
| Low MS et al. | 2016 | Meta-analysis | Cochrane Database of Systematic Reviews | View on PubMed |
Daily iron supplementation for improving anaemia, iron status and health in menstruating women Cochrane systematic review of 67 trials and 8,506 menstruating women: daily supplementation raises haemoglobin and iron stores, improves exercise performance and appears to reduce symptomatic fatigue, at the cost of more frequent digestive effects. | ||||
| Houston BL et al. | 2018 | Meta-analysis | BMJ Open | View on PubMed |
Efficacy of iron supplementation on fatigue and physical capacity in non-anaemic iron-deficient adults: a systematic review of randomised controlled trials Systematic review of 18 trials and 1,170 adults with low stores but no anaemia: reduced self-reported fatigue scores across 714 participants, with no improvement in objective measures of physical capacity. | ||||
| Milman N et al. | 2014 | Randomised Controlled Trial | Journal of Perinatal Medicine | View on PubMed |
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 Randomised double-blind trial in 80 Danish pregnant women, from week 15 to delivery: iron bisglycinate at 25 mg was not inferior to ferrous sulphate at 50 mg, with fewer digestive complaints. | ||||
| Fischer JAJ et al. | 2023 | Meta-analysis | Nutrition Reviews | View on PubMed |
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 Meta-analysis of 17 randomised trials: in pregnant women, iron bisglycinate yields higher haemoglobin and around two thirds fewer digestive events than other iron forms. In children, no difference, and other populations remain too little studied. | ||||
| Tolkien Z et al. | 2015 | Meta-analysis | PLoS One | View on PubMed |
Ferrous sulfate supplementation causes significant gastrointestinal side-effects in adults: a systematic review and meta-analysis Meta-analysis of 43 trials and 6,831 adults: ferrous sulphate multiplies the risk of digestive effects by 2.3 compared with placebo, with no relationship found with dose. | ||||
| Vaucher P et al. | 2012 | Randomised Controlled Trial | CMAJ | View on PubMed |
Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial Randomised trial in 198 women aged 18 to 53 with low ferritin and normal haemoglobin: 80 mg of elemental iron daily for 12 weeks reduced the fatigue score, with no effect on quality of life, mood or anxiety. | ||||
| Stoffel NU et al. | 2017 | Randomised Controlled Trial | The Lancet Haematology | View on PubMed |
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 Two open-label randomised trials: cumulative fractional iron absorption is higher with single morning doses on alternate days than with closely spaced daily doses. | ||||
| Murray-Kolb LE, Beard JL | 2007 | Randomised Controlled Trial | The American Journal of Clinical Nutrition | View on PubMed |
Iron treatment normalizes cognitive functioning in young women Controlled intervention study in 149 women aged 18 to 35, over 16 weeks: a rise in ferritin was accompanied by better cognitive scores, and a rise in haemoglobin by faster task completion. The effect is reported as an association, not as a between-group comparison. | ||||
| Pasricha SR et al. | 2021 | Review | The Lancet | View on PubMed |
Iron deficiency Comprehensive Lancet review covering iron physiology, functional consequences of low stores, and evidence-based supplementation strategies. | ||||