Magnesium Citrate

Magnesium citrate is one of the most widely used magnesium salts as a food supplement because of its good digestive tolerance and its bioavailability. It contributes to the reduction of tiredness and fatigue, to the normal functioning of the nervous system, to normal muscle function and to another 7 physiological functions officially authorised in Europe. This page covers how it works, how it compares with other magnesium salts (bisglycinate, malate, oxide), the doses studied and where it fits within the Pleniage portfolio.

What is magnesium citrate?

Magnesium citrate is the salt formed when magnesium (a mineral that is essential for the human body) combines with citric acid (the organic acid characteristic of citrus fruits). It is one of the most widely used forms of magnesium in food supplementation for two practical reasons: it has good digestive tolerance (it usually causes fewer intestinal complaints than other salts such as oxide) and an adequate bioavailability (the body absorbs a reasonable proportion of the ingested dose).

Magnesium itself is one of the most important minerals for human physiology. An adult body contains about 25 g of magnesium, distributed mainly in the bones (around 60%) and in the soft tissues. It is an enzymatic cofactor —a molecule that enzymes need in order to function correctly— of more than 300 biochemical reactions, which justifies its role in energy metabolism, muscle and nerve function, and protein synthesis, among many other functions we will look at below.

What is it used for? Functions authorised in Europe

In Europe, the EFSA (European Food Safety Authority) has evaluated the physiological functions of magnesium and has officially authorised ten health claims for this mineral. It is one of the nutrients with the highest number of authorised green EFSA claims, reflecting the diversity of biological functions in which it takes part. These claims may be used in the labelling and communication of food supplements that provide at least 15% of the nutrient reference value (NRV) per recommended dose.

Reduction of tiredness and fatigue

Magnesium contributes to the reduction of tiredness and fatigue (authorised EFSA claim, ID 244). This function reflects the central role of magnesium in cellular energy metabolism: adequate metabolic efficiency translates into better energy availability for the body's daily functions.

Normal functioning of the nervous system

Magnesium contributes to the normal functioning of the nervous system (authorised EFSA claim, ID 242). Magnesium is involved in nerve transmission by modulating the ionic balance in the membranes of nerve cells and the release of neurotransmitters at the synapses.

Normal muscle function

Magnesium contributes to normal muscle function (authorised EFSA claim, ID 241). Magnesium takes part in the muscle contraction-relaxation cycle, balancing the action of calcium in the muscle fibres. Adequate magnesium function is necessary for muscles to work and recover correctly.

Normal energy-yielding metabolism

Magnesium contributes to normal energy-yielding metabolism (authorised EFSA claim, ID 233). This function is linked to its role as a cofactor of many enzymes involved in the production of ATP, the "energy currency" of cells.

Other officially authorised functions

In addition to the above, magnesium has six additional green EFSA claims, all of them with the same level of regulatory backing:

• Electrolyte balance (authorised EFSA claim, ID 235): magnesium is one of the essential ions for the balance between the body's fluid compartments.
• Normal psychological function (authorised EFSA claim, ID 245): contribution to the balance of the central nervous system at a functional level.
• Maintenance of normal bones (authorised EFSA claim, ID 239): magnesium is one of the mineral components of bone tissue.
• Maintenance of normal teeth (authorised EFSA claim, ID 236).
• Normal protein synthesis (authorised EFSA claim, ID 234): cofactor in the translation of proteins.
• Process of cell division (authorised EFSA claim, ID 240): cofactor in the enzymes involved in DNA replication.

How it works: cofactor of more than 300 reactions

Magnesium is one of the most prevalent enzymatic cofactors in the human body. It takes part in more than 300 different biochemical reactions, which explains why it is involved in so many diverse physiological functions. The most important functional areas include:

• Cellular energy production (ATP): magnesium associates with the ATP molecule in its active form (Mg-ATP), which is the form usable by metabolic enzymes. Without magnesium, ATP cannot release its energy to cellular processes.
• Synthesis and repair of DNA and RNA: cofactor in the polymerases that copy and repair the genetic material.
• Protein synthesis: cofactor in the formation of peptide bonds during ribosomal translation.
• Nerve transmission and muscle contraction: it regulates the ion channels of excitable membranes (nerves and muscles), modulating the balance with calcium.
• Stabilisation of cellular and mitochondrial membranes.
• Cofactor in the metabolism of glucose, lipids and amino acids.

This multiplicity of functions is the biochemical basis of the ten authorised green EFSA claims.

Citrate vs other magnesium salts

Elemental magnesium is never administered as an isolated supplement: it is always used in the form of a salt, that is, bound to another molecule that stabilises it and modulates its absorption. The different magnesium salts differ in two key practical aspects: bioavailability (what proportion of the elemental magnesium is absorbed by the intestine) and digestive tolerance (how much laxative effect or other gastrointestinal effects they produce).

This comparison explains why the choice of magnesium salt matters and why professional supplements always specify the exact salt used (not just "magnesium"). Citrate is one of the most widely used options for its good balance between absorption and tolerance.

Food sources and daily requirements

Magnesium is present in a wide variety of foods. The sources with the highest concentration are:

• Dark green leafy vegetables (spinach, chard, kale): magnesium is part of the centre of the chlorophyll molecule.
• Nuts and seeds (almonds, cashews, pumpkin seeds, sunflower seeds).
• Legumes (beans, lentils, chickpeas, peas).
• Whole grains (whole oats, whole wheat, brown rice, quinoa).
• Pure cocoa and dark chocolate with a high cocoa percentage.
• Oily fish (mackerel, salmon, sardines).
• Avocado, banana.
• Mineral waters rich in magnesium.

The nutrient reference value (NRV) in the European Union for magnesium is 375 mg/day (EU Regulation 1169/2011 on food information). International recommendations for adults range between 320 mg/day (women) and 420 mg/day (men) according to the US National Academies.

Deficiency: signs and at-risk populations

Unlike other vitamins and minerals, subclinical magnesium deficiency (that is, levels below optimal without clear symptoms of overt deficiency) is relatively frequent in the general population of Western countries. Several factors explain this prevalence: the loss of magnesium during food refining processes (refined grains, sugar), the increased consumption of ultra-processed foods, the decline in the mineral content of some agricultural soils, and population factors (advanced age, certain chronic medications, chronic digestive diseases).

Signs and symptoms of low levels

Mild to moderate magnesium deficiency can manifest in a non-specific way: tiredness, irritability, occasional muscle cramps, sleep disturbances. Severe deficiency can produce clearer clinical signs (electrolyte disturbances, marked muscle spasms, heart rhythm disturbances) and requires specialist medical assessment.

Populations at greater risk

• Older people: intestinal absorption of magnesium decreases with age and its renal excretion increases.
• People on chronic treatment with diuretics, proton pump inhibitors (PPIs) or certain antibiotics: these medications increase magnesium loss.
• People with chronic digestive diseases (inflammatory bowel disease, malabsorption): they reduce intestinal absorption.
• People with poorly controlled type 2 diabetes: it increases urinary excretion of magnesium.
• Athletes with intense training: additional losses through sweat.
• People with high alcohol consumption.

Studied doses and bioavailability

Magnesium citrate supplements typically provide between 100 and 400 mg of elemental magnesium per dose (an amount referring to elemental magnesium, not to the weight of the complete salt, which is greater). The usual regimens in general maintenance supplementation are between 200 and 400 mg/day. In specific clinical contexts, doses can be adjusted under medical supervision.

The bioavailability of magnesium depends on several factors:

• Salt used: organic salts (citrate, bisglycinate, malate) have higher bioavailability than inorganic oxide.
• Dose: doses split across several intakes tend to be better absorbed than a single high dose.
• Taking with or without food: citrate is well absorbed with or without food.
• Gastric acidity: adequate gastric acidity favours the solubility of the salts. People on prolonged treatment with proton pump inhibitors may have reduced absorption.
• Baseline nutritional status: in people with depletion, absorption tends to increase as an adaptive mechanism.

An analytical series published in Nutrients (Pajuelo et al., 2024) compared the absorption of different magnesium formulations in humans, confirming that the differences between salts are clinically relevant for supplement choice. Another study published in Biometals (Ivanovic et al., 2022) evaluated how magnesium supplementation modifies serum levels of ionized and total magnesium in the short term, providing data on absorption kinetics.

Safety and precautions

Magnesium in supplementation at the usual doses has a favourable safety profile. EFSA has established a tolerable upper level of 250 mg/day of elemental magnesium from food supplements (not counting dietary magnesium), a limit set specifically because of the laxative effect of magnesium salts at higher doses. This limit is conservative and does not imply toxicity above it, but rather the threshold below which no gastrointestinal effects are observed in most people.

Common adverse effects

The most frequent adverse effect of magnesium in supplementation is the laxative effect (loose stools or diarrhoea), which depends greatly on the salt used and on the dose. Oxide and sulfate are the most laxative; citrate has a moderate laxative effect at high doses; bisglycinate is the best tolerated in this respect. If this effect appears, it usually resolves by splitting or reducing the dose.

Relevant pharmacological interactions

• Quinolone and tetracycline antibiotics: magnesium can reduce the intestinal absorption of these antibiotics. Separate the intakes by at least 2 hours.
• Bisphosphonates (osteoporosis): magnesium reduces their absorption. Separate the intakes.
• Levothyroxine: separate the intakes by at least 4 hours.
• Diuretics and other cardiac medications: they can modify the renal excretion of magnesium. People on chronic treatment should consult their doctor before supplementing.

Renal insufficiency

People with moderate or severe renal insufficiency have a reduced capacity to excrete excess magnesium and may accumulate the mineral with supplementation. Magnesium supplementation in these people requires specialist medical supervision and should NOT be started without consulting the nephrologist.

How to choose a supplement

Key technical criteria for selecting a magnesium citrate supplement:

• Salt specified explicitly: avoid products that only say "magnesium" without indicating the salt. Professionally, the labelling should declare "magnesium citrate" (or the corresponding salt).
• Clear elemental magnesium dose: the labelling should distinguish between the total weight of the salt and the elemental magnesium content. What matters for supplementation is this second figure.
• Divisible dose: capsules or sachets that allow the dose to be adjusted to the usual intakes.
• Purity and traceability: third-party certificates of analysis (USP, NSF) where available.
• Consistency with the indication: if the goal is rest/calm, bisglycinate may be preferred; for general use, citrate is a good option; oxide is avoided except for budget limitations.
• Absence of unnecessary additives: avoid formulations with titanium dioxide, excess magnesium stearate or artificial colourings.

Magnesium citrate in the Pleniage portfolio

In the PLENIAGE® ENERGY PRO formulation, magnesium citrate is incorporated together with the complete B complex (B1, B2, B3, B5, B6, B12), alpha-lipoic acid (175 mg), vitamin C, vitamin E and biotin. The formula is designed to provide magnesium (cofactor of >300 enzymatic reactions) in a coordinated way, in synergy with the B-group vitamins (cofactors of energy metabolism) and the antioxidants involved in cellular function. Each ingredient has its own individual scientific research and, in the case of magnesium, ten officially authorised claims in Europe; the specific combination of this formula has not been the subject of its own clinical trial.

The choice of the citrate salt in ENERGY PRO is due to its good balance between bioavailability and digestive tolerance. For more detail on how it compares with other salts, see the H2-4 section of this same page.

This page is part of the Energy and performance cluster. To explore other related components in more depth, see the Alpha-lipoic acid page (a complementary mitochondrial cofactor in the formula) and the Vitamin B5 page (part of the B complex in the same formula).

Frequently asked questions about magnesium citrate

Is saying "magnesium citrate" the same as "citrate of magnesium"?

Yes, they are two ways of referring to the same salt. They both refer to magnesium combined with citric acid. On European food-supplement labels, "trimagnesium dicitrate" may also appear as the full chemical name.

What is magnesium citrate used for?

In Europe, magnesium has ten claims officially authorised by EFSA, including: it contributes to the reduction of tiredness and fatigue (ID 244), to the normal functioning of the nervous system (ID 242), to normal muscle function (ID 241), to normal energy-yielding metabolism (ID 233), to electrolyte balance (ID 235), to normal psychological function (ID 245), to the maintenance of normal bones (ID 239) and teeth (ID 236), to normal protein synthesis (ID 234) and to the process of cell division (ID 240). These functions reflect the role of magnesium as a cofactor of more than 300 biochemical reactions.

Which magnesium salt is best: citrate, bisglycinate or oxide?

It depends on the goal. Citrate has a good balance between bioavailability and digestive tolerance, which is why it is one of the most widely used options for general supplementation. Bisglycinate (the form chelated with glycine) is the best tolerated digestively and is often preferred in supplements aimed at rest/calm. Oxide has low bioavailability and poorer digestive tolerance, although it is cheaper. For general maintenance use, organic salts (citrate, bisglycinate, malate) are preferable to inorganic oxide.

How much magnesium citrate can I take per day?

The nutrient reference value (NRV) in the European Union for magnesium is 375 mg/day of elemental magnesium. EFSA has established a tolerable upper level of 250 mg/day of elemental magnesium from food supplements only (not counting dietary magnesium), a limit set because of the laxative effect at higher doses. The usual maintenance supplementation regimens are between 200 and 400 mg of elemental magnesium per day, split across several intakes. People with renal insufficiency or on chronic treatment with diuretics should consult their doctor before supplementing.

Does magnesium citrate have side effects?

The most frequent adverse effect is the laxative effect (loose stools or diarrhoea), especially at high doses or when the whole dose is concentrated into a single intake. Citrate has a moderate laxative effect at high doses, lower than oxide or sulfate. If this effect appears, it usually resolves by splitting or reducing the dose. People with moderate or severe renal insufficiency require medical supervision in order to supplement, as they may accumulate magnesium.

Does it have interactions with medications?

Yes, several relevant ones. Magnesium can reduce the absorption of quinolone antibiotics (ciprofloxacin) and tetracyclines (separate the intakes by at least 2 hours), of bisphosphonates (osteoporosis medication) and of levothyroxine (separate by at least 4 hours). People on chronic treatment with diuretics or cardiac medication may have altered renal excretion of magnesium and should consult their doctor before starting supplementation.

Does magnesium citrate help you sleep better?

Magnesium contributes to normal psychological function (authorised EFSA claim, ID 245) and to the normal functioning of the nervous system (EFSA claim, ID 242). In people with low magnesium levels, correcting the deficit may improve sleep quality. However, magnesium supplements aimed specifically at rest often use the bisglycinate salt (better tolerated and with no notable laxative effect, which avoids night-time awakenings due to intestinal urgency). Magnesium citrate is also valid for this use, but it is important to adjust the dose and the timing of intake to avoid the laxative effect at night.

Magnesium citrate is one of the most widely used magnesium salts in supplementation because of its good balance between bioavailability and digestive tolerance. Magnesium itself is one of the minerals with the highest number of authorised green EFSA claims (ten), reflecting its central role as an enzymatic cofactor in more than 300 biochemical reactions. The choice of magnesium salt matters: organic salts such as citrate, bisglycinate or malate are preferable to inorganic oxide for maintenance supplementation. If you are interested in exploring energy-support strategies in more depth, consult your doctor or pharmacist to assess whether magnesium supplementation is appropriate for your situation.

At PLENIAGE® we publish scientific content on evidence-based supplementation. You can explore the Energy and performance cluster for more pages and related articles.

---

References

The statements in this article are based on the available scientific literature and on the health claims officially authorised by EFSA (European Food Safety Authority).

• EFSA Health Claims Register — magnesium: authorised claims ID 233 (normal energy-yielding metabolism), 234 (normal protein synthesis), 235 (electrolyte balance), 236 (maintenance of normal teeth), 239 (maintenance of normal bones), 240 (process of cell division), 241 (normal muscle function), 242 (normal functioning of the nervous system), 244 (reduction of tiredness and fatigue), 245 (normal psychological function). Official source: EU Register of Nutrition and Health Claims.
• EU Regulation 1169/2011 on the provision of food information to consumers — Annex XIII (nutrient reference value NRV for magnesium: 375 mg/day).
• EFSA Panel on Dietetic Products, Nutrition and Allergies — Tolerable Upper Intake Level (UL) for magnesium from food supplements: 250 mg/day.
• Boyle NB, Lawton C, Dye L. The Effects of Magnesium Supplementation on Subjective Anxiety and Stress—A Systematic Review. Nutrients. 2017;9(5):429. PMID: 28445426.
• Pickering G, Mazur A, Trousselard M, et al. Magnesium Status and Stress: The Vicious Circle Concept Revisited. Nutrients. 2020;12(12):3672. PMID: 33260549.
• Pajuelo D, Meissner JM, Negra T, Connolly A, Mullor JL. Comparative Clinical Study on Magnesium Absorption and Side Effects After Oral Intake of Microencapsulated Magnesium (MAGSHAPETM Microcapsules) Versus Other Magnesium Sources. Nutrients. 2024. PMID: 39770988.
• Ivanovic ND, Radosavljevic B, Zekovic M, et al. Effects of short-term magnesium supplementation on ionized, total magnesium and other relevant electrolytes levels. Biometals. 2022. PMID: 35041150.