Citrate malate

Other Names

1,2,3-propanetricarboxylic acid, 2-hydroxy-, calcium salt2-hydroxy-1,2,3-propanetricarboxylic acid calcium salt mixture with hydroxybutanedioic acid calcium saltbutanedioic acid, hydroxy-, calcium saltcalcium 2-hydroxybutanedioatecalcium citrate malatecalcium citrate malate pentahydratecalcium citrate malate saltCCMcitric acid malic acid calcium saltcitric and malic acids calcium saltfruit acid calciumhexacalcium 2-hydroxybutanedioate 2-hydroxypropane-1,2,3-tricarboxylate hexahydrate

Synopsis

Citrate Malate: A Comprehensive Encyclopedic Reference

1. Identity, Chemical Names, and Structural Forms

The term citrate malate refers not to a single, fixed chemical compound but to a family of salts and complexes formed by combining citric acid (or its anion, citrate) with malic acid (or its anion, malate), typically alongside a mineral cation — most commonly calcium, but also magnesium, potassium, iron, and others. In common commercial and scientific usage, the phrase "citrate malate" almost always appears as part of a mineral salt designation: calcium citrate malate (CCM), magnesium citrate malate, or, in a structurally distinct supplement category, citrulline malate (in which the nitrogenous amino acid L-citrulline, rather than citric acid, is paired with malate). Each of these is addressed in this article.

Calcium citrate malate is the calcium salt of citric acid and malic acid with variable composition. It does not have a fixed defined structure; it may consist of a mixture of calcium citrate and calcium malate, a complex of calcium containing citrate and malate ligands, a mixture of a calcium salt with citric acid and malic acid, or combinations thereof. The composition is more soluble than calcium citrate or calcium malate alone, and when prepared by the established process, consists of a metastable complex salt which is distinct from either pure calcium citrate or pure calcium malate.

The molar ratio of citrate to malate in calcium citrate malate preparations ranges from about 1:0.16 to about 1:13.5, with a preferred molar citrate:malate ratio of about 1:1.5 cited in foundational patent literature. A preferred calcium citrate malate has a calcium:citrate:malate molar composition of about 6:2:3 or 4:2:1.

A Japanese patent application (SHO 56/097,248, Tanaka, 1981) first described a calcium citrate malate salt of increased solubility; this salt uses a 5:2:2 ratio of calcium:citrate:malate, with 2 molecules of calcium malate associated with 1 molecule of calcium citrate. The product is described as a white crystalline powder soluble at 0.5 g/100 ml of water at 20°C and with a pH of 6 to 6.5.

PubChem records calcium citrate malate under CID 156596391, with the molecular formula C₂₄H₃₄Ca₆O₃₅ for one common stoichiometry, while a simpler salt form (CID 86746885) carries the formula C₁₀H₁₂CaO₁₂. Both entries are catalogued by PubChem, which records their structure, chemical names, physical and chemical properties, classification, biological activities, and safety information.

Citrulline malate is a structurally different compound. As an organic salt, citrulline malate is formed through the combination of L-citrulline (C₆H₁₃N₃O₃), a non-essential amino acid involved in the urea cycle, and malate (or malic acid, C₄H₆O₅), a tricarboxylic acid (TCA) intermediate. In commercial supplements, the most commonly sold ratio is 2:1 (L-citrulline to malic acid by weight).

2. Constituent Components and Their Natural Sources

2.1 Malic Acid / Malate

Malic acid has two stereoisomeric forms (L- and D-enantiomers), though only the L-isomer exists naturally. The salts and esters of malic acid are known as malates. The malate anion is a metabolic intermediate in the citric acid cycle. The word "malic" is derived from the Latin mālum, meaning "apple." Malic acid was first isolated from apple juice by Carl Wilhelm Scheele in 1785; Antoine Lavoisier in 1787 proposed the name acide malique, derived from the Latin word for apple.

Malic acid is a naturally occurring organic acid found in many fruits, including apples, cherries, grapes, and pears; it has a sour taste but is milder than citric acid, providing a smooth and persistent sourness. L-malic acid is the naturally occurring form, whereas a mixture of L- and D-malic acid is produced synthetically. Industrially, world production of malic acid is estimated at around 60,000 tonnes per year, most of it made by chemical hydration of maleic or fumaric acid at high temperature (180–220°C) and high pressure (14–18 bar), yielding the racemic mixture of DL-malic acid; biological processes produce only the L-isomer.

2.2 Citric Acid / Citrate

Citric acid is the first committed intermediate of the TCA cycle, formed from the condensation of acetyl-CoA and oxaloacetate, catalyzed by citrate synthase; its primary role is to initiate the oxidative breakdown of carbon substrates. It occurs abundantly in citrus fruits (lemons, limes, oranges), berries, and many other plant sources. Industrially, it is produced by fermentation of sugars using Aspergillus niger.

2.3 L-Citrulline (in citrulline malate)

L-Citrulline is a non-essential amino acid that occurs naturally in watermelon (Citrullus lanatus), from which its name derives, as well as in cucumbers, squash, and other cucurbits. It is an intermediate in the hepatic urea cycle. In supplement manufacturing, L-citrulline is produced synthetically or by fermentation.

3. Common Preparations and Dosage Forms

Citrate malate-based ingredients are commercially available in several forms:

Calcium citrate malate (CCM): Sold as tablets, capsules, and powder; also used to fortify beverages and juices. Calcium citrate malate can be provided as a solid or liquid solution.
Magnesium citrate malate: Available in tablet and powder form, marketed primarily for energy support and muscle function.
Citrulline malate: Predominantly sold as a bulk powder or in pre-workout capsules, with the 2:1 ratio (L-citrulline:malic acid by weight) being the most widely distributed form.
Magnesium malate: Tablets or capsules, sometimes labeled "malic acid + magnesium."

Various calcium salts are in clinical use and include carbonate, phosphate, citrate, and citrate malate. Calcium citrate malate is a well-absorbed form of calcium used in some fortified juices.

The preparation of calcium citrate malate typically involves reacting a calcium base (carbonate, hydroxide, or oxide) with a solution of citric and malic acids. Preferred calcium citrate malate mixtures are made by adding calcium carbonate, calcium hydroxide, or other suitable source to a mixture of citric and malic acids. Finished compositions may contain at least about 15%, and in some formulations at least about 20%, calcium by weight of the calcium citrate malate composition.

4. Traditional and Historical Use

Citric acid and malic acid, the component acids of citrate malate, have long individual histories in food, medicine, and pharmacopoeia, though the specific combined salt form "citrate malate" was a twentieth-century invention arising from nutritional science and the food fortification industry.

Malic acid has been used empirically for centuries in fermented foods and traditional beverages, deriving from its natural presence in fruit. In folk and early medical traditions across Europe and Asia, sour fruit juices containing malic and citric acids were employed as tonics, digestive aids, and to prevent scurvy-like conditions. However, these uses applied to the whole fruit or juice matrix, not to isolated or combined salt forms.

Citrate salts have a recognized pharmacopeial history. Potassium citrate and sodium citrate appear in classical dispensatories as urinary alkalinizers and antacids. Citric acid salts are used clinically to correct metabolic acidosis.

Citrulline malate has a more recent and specifically European pharmaceutical history. The ingestion of citrulline malate was originally prescribed to enhance the muscle performance of patients suffering from asthenia and to facilitate the recovery of muscle function resulting from acute diseases. It was used clinically in France from the 1970s onward, and a branded oral form (Stimol, a 1.76 g/dose oral solution) was registered as a pharmaceutical product for convalescence and asthenia in several European countries before the compound migrated into the sports nutrition market.

The specific calcium citrate malate complex as a defined supplement entity emerged primarily in the 1980s from food science research, particularly the effort to fortify orange and apple juices with highly bioavailable calcium. Smith et al. ("Calcium Absorption from a New Calcium Delivery System (CCM)", Calcified Tissue International, 41: 351–352, 1987) reported an experiment in humans wherein calcium from CCM was absorbed significantly better than from either calcium carbonate or milk — 38.3% vs. 29.6% and 29.4% respectively. This landmark finding drove widespread industrial interest.

5. Key Constituents, Biochemistry, and Mechanisms of Action

5.1 Role of Malate in Cellular Energy Metabolism

Malic acid, especially in the form of its anion malate, is a key intermediate in the major biochemical energy-producing cycle in cells — the citric acid or Krebs cycle — located in the cells' mitochondria. Malic acid appears in the TCA cycle, generated from fumarate by the enzyme fumarase, and is then converted to oxaloacetate via malate dehydrogenase, producing NADH in the process — critical for ATP generation via oxidative phosphorylation.

Citric acid is a key carbon source for fat synthesis, while malic acid participates in gluconeogenesis and the malate-aspartate shuttle to maintain mitochondrial redox balance. The malate-aspartate shuttle is the primary mechanism by which cytosolic NADH equivalents are transferred into the mitochondria for oxidative phosphorylation, underscoring malate's role beyond simple TCA intermediate status.

Malic acid weakly acts as an antioxidant but chelates metal ions (Fe²⁺, Cu²⁺) to reduce hydroxyl radical formation and support glutathione activity. Citric acid is a strong chelator that inhibits lipid peroxidation and prevents calcium oxalate kidney stones.

5.2 Mechanism of Action of Calcium Citrate Malate

Calcium citrate malate's bioavailability stems from its water-solubility and its method of dissolution; when dissolved, it releases calcium ions and a calcium citrate complex. Calcium citrate malate is claimed to be approximately six times the solubility of either calcium citrate or calcium malate, both of which are themselves substantially more soluble than calcium carbonate.

Fructose in orange juice and apple juice has been shown to promote positive calcium bioavailability from calcium citrate malate, and organic acids such as citric acid, malic acid, and ascorbic acid may also play a role in the favorable absorption of calcium from CCM. Citrate forms soluble, non-ionized complexes with calcium in the intestinal lumen that maintain calcium in solution at neutral and higher pH ranges, facilitating passive diffusion and transcellular transport across the intestinal epithelium.

Calcium citrate malate provides elemental calcium of 26% and bioavailability of above 35%, which is reported as the highest among all calcium formulations available. Calcium citrate malate has better absorption in high gastric pH as compared to calcium carbonate. This is a clinically relevant advantage for elderly patients and individuals with achlorhydria or those taking acid-suppressing medications.

5.3 Mechanisms of Action of Citrulline Malate

As a nitric oxide (NO) enhancer, citrulline malate has been touted as a potential ergogenic aid to both resistance and high-intensity exercise performance as well as the recovery of muscular performance. The mechanism has been associated with enhanced blood flow to active musculature, though it might be more far-reaching in that ammonia homeostasis could be improved, or ATP production could be increased via greater availability of malate. Moreover, citrulline malate might improve muscle recovery via increased nutrient delivery and/or removal of waste products.

More specifically, the proposed mechanism for citrulline malate ingestion is firstly dependent on the citrulline component via the L-arginine-NO pathway, such that following NO synthesis the smooth muscle may relax, leading to vasodilation. Outside of the common practice of oral supplementation of beetroot juice, L-citrulline ingestion has been the most researched nutritional strategy to stimulate NO production; this is likely explained by studies showing L-citrulline ingestion to be the most efficient means of elevating plasma arginine concentrations, which in turn produces NO.

Malate is an intermediate of the tricarboxylic acid (TCA) cycle, and its greater availability after citrulline malate supplementation may augment aerobic ATP production by the TCA cycle through anaplerotic reactions, resulting in decreased muscle fatigue and improved muscle performance. Citrulline malate has been reported to augment aerobic energy production during exercise and increase phosphocreatine (PCr) during exercise recovery, improve ammonia (NH₃) elimination during recovery from exhaustive exercise, attenuate muscle soreness after high-intensity resistance exercise, and increase performance during repeated bouts of high-intensity resistance exercise.

Regarding the relative contribution of each component: it has been suggested that citrulline is the active ingredient, as malic acid is utilised to allow the supplement to form a stable salt for storage and neutralise the basicity of the supplement; nonetheless, the malic acid portion of the supplement has also been attributed a role as an intermediate utilised in the citric acid cycle.

5.4 Mechanisms of Action of Magnesium Malate

A central hypothesis for magnesium malate's clinical relevance posits that fibromyalgia symptoms are predominantly caused by enhanced gluconeogenesis with breakdown of muscle proteins, resulting from a deficiency of oxygen and other substances needed for ATP synthesis; data supporting a critical role for magnesium and malate in ATP production under aerobic and hypoxic conditions, and indirect evidence for magnesium and malate deficiency in fibromyalgia, has been presented. Magnesium is an essential cofactor for numerous ATP-producing enzymatic reactions, while malate serves as an anaplerotic substrate that can sustain TCA cycle flux when oxygen delivery is limited.

6. Scientific Evidence by Area of Use

6.1 Bone Health and Osteoporosis (Calcium Citrate Malate)

The strongest and most consistent body of human evidence for calcium citrate malate concerns skeletal health. Multiple controlled trials have examined its effects on bone mineral density (BMD) across different populations.

Postmenopausal women: A double-blind, placebo-controlled, randomized trial enrolled 301 healthy postmenopausal women, half with a calcium intake lower than 400 mg/day and half with an intake of 400 to 650 mg/day; the women received placebo, calcium carbonate, or calcium citrate malate at 500 mg of calcium per day for two years. In those with the lower calcium intake, calcium citrate malate prevented bone loss during the two years of the study; its effect was significantly different from placebo (P < 0.05) at the femoral neck (mean change in bone density, 0.87 ± 1.01% vs. −2.11 ± 0.93%), radius (1.05 ± 0.75% vs. −2.33 ± 0.72%), and spine (−0.38 ± 0.82% vs. −2.85 ± 0.77%). Calcium carbonate maintained bone density at the femoral neck and radius but not the spine. This trial was published in the New England Journal of Medicine in 1990 and remains one of the most-cited studies in this area.

Children and adolescents: A three-year, double-blind, placebo-controlled trial examined the effect of 1,000 mg of calcium citrate malate per day on bone mineral density in 70 pairs of identical twins (mean age 10 ± 2 years; range, 6–14); 45 pairs completed the study, with bone mineral density measured by photon absorptiometry at two sites in the radius and at three sites in the hip and spine. Results supported supplemental calcium's benefit for bone accrual during growth. The vast majority of peak adult bone mass is accumulated by the time longitudinal growth is complete; as peak bone mass is an important determinant of future fracture risk, the goal of calcium intake during youth is to allow individuals to reach their full genetic potential for acquiring skeletal mass. Studies using calcium citrate malate indicated that the then-current RDAs were insufficient to support optimal bone mass gain during growth and development.

Elderly adults (men and women ≥65 years): A published PubMed-indexed trial (Dawson-Hughes et al., NEJM, 1997) examined the effect of calcium (500 mg/day as calcium citrate malate) and vitamin D supplementation on bone density in men and women aged 65 or older, finding significant benefits for bone density preservation and, notably, a reduction in nonvertebral fractures.

Osteopenia comparative study: A randomized open-label clinical study evaluated the efficacy, safety, and bioavailability of calcium lysinate in comparison to other calcium supplements in improving BMD in osteopenia patients; 24 osteopenia patients were randomly divided into three groups of eight, receiving calcium lysinate, calcium carbonate, or calcium citrate malate. There was significant improvement in the T-score of BMD in all groups. The study's small sample size (n=8 per group) is a significant limitation.

Evidence assessment: For postmenopausal and elderly populations with low calcium intake, the evidence from randomized controlled trials supports calcium citrate malate's efficacy in preserving bone mineral density. However, whether calcium supplementation in adequately nourished individuals prevents fractures is less clear. Calcium and vitamin D supplementation does not reduce fracture risk in community-dwelling and institutionalized middle-aged to older adults according to some analyses. The NIH Office of Dietary Supplements notes that it is not clear whether calcium supplements help prevent fractures, and more research is needed to better understand whether consuming more calcium from food or supplements improves bone health in older adults.

6.2 Calcium Bioavailability (Comparative Studies)

The European Food Safety Authority (EFSA) has concluded that calcium citrate malate is "slightly more bioavailable" than other forms of calcium supplementation. EFSA's scientific opinion on dietary reference values for calcium noted reports of higher percentage absorption from calcium citrate malate. The EFSA Panel on Food Additives evaluated calcium citrate malate in 2007 as a source for calcium added to foods for Particular Nutritional Uses, food supplements, and foods intended for the general population.

The absorption kinetics of orally administered calcium depend on the absolute amount of calcium; as the dose of calcium increases, the percentage absorbed decreases. According to the American Association of Clinical Endocrinology (AACE), patients with achlorhydria, a history of gastric surgery, or receiving proton-pump inhibitors or H2-receptor blockers should be prescribed calcium citrate over calcium carbonate. Calcium citrate malate shares this advantage, as it does not require an acidic gastric environment for dissolution. Among all formulations, calcium carbonate and calcium citrate malate are the most common formulations used clinically; the maximum dosage of elemental calcium that can be taken in a single dose is 500 mg or less.

6.3 Exercise Performance and Athletic Recovery (Citrulline Malate)

The use of citrulline malate as a pre-workout ergogenic aid has been the subject of numerous clinical trials since the 2000s, though results have been inconsistent.

To date, a single acute 8 g dose of citrulline malate on either resistance exercise performance or cycling has been the most common approach, which has produced equivocal results, making the effectiveness of citrulline malate to improve exercise performance difficult to determine.

The mechanism has been associated with enhanced blood flow to active musculature; however, it might be more far-reaching as either ammonia homeostasis could be improved, or ATP production could be increased via greater availability of malate. Moreover, citrulline malate might improve muscle recovery via increased nutrient delivery and/or removal of waste products.

One influential study by Pérez-Guisado and Jakeman (2010), frequently cited in the literature, reported that total repetitions during four sets to failure at 80% of one-repetition maximum were improved significantly following ingestion of 8 g citrulline malate. However, these effects are not universal across studies, with many reporting no effects of citrulline malate ingestion on resistance exercise protocols.

A double-blind crossover study in young adult men examined recovery: nine young adult men (24.0 ± 3.3 years) received 6 g of citrulline malate and placebo on two occasions, separated by a seven-day washout period; each occasion consisted of a single session of high-intensity resistance exercise and three subsequent fatigue test sessions at 24, 48, and 72 h to assess the time course of muscle recovery. In this particular study, citrulline malate did not improve muscle recovery.

A 2021 critical review in the European Journal of Applied Physiology concluded: to date, a single acute 8 g dose of citrulline malate on either resistance exercise performance or cycling has been the most common approach, which has produced equivocal results, making the effectiveness difficult to determine; reasons for the disparity in conclusions appear to be due to methodological discrepancies such as the testing protocols and the associated test–retest reliability, and dosing strategy.

Regarding dose-response, one randomized double-blind crossover pilot trial investigated a moderate (8 g; CM-MOD) and high (12 g; CM-HIGH) dose of citrulline malate on resistance exercise performance in twelve resistance-trained individuals (7 females, 5 males, age = 24 ± 2 years); participants completed barbell bent-over rows and leg presses following acute ingestion of either 8 g CM, 12 g CM, or a placebo 1 h prior to exercise.

The evidence to date specifically on citrulline malate supplementation suggests that enhanced blood flow caused by the citrulline component is not the acting mechanism, although further experimental research is required.

Evidence assessment: Overall, evidence for citrulline malate's ergogenic effects is preliminary and inconsistent. While individual studies show performance improvements, the body of evidence does not yet support firm conclusions. Sample sizes are generally small, protocols vary significantly, and blinding is sometimes inadequate. Further, questions about the actual molar content of citrulline in commercial products complicate interpretation.

6.4 Fibromyalgia and Musculoskeletal Pain (Magnesium Malate)

Malic acid is considered an important compound, together with magnesium, for the treatment of fibromyalgia, a rheumatic illness which primarily affects middle-aged women. The theoretical rationale links malate's role as a TCA intermediate to energy deficits hypothesized in fibromyalgia musculature.

Abraham and Flechas treated 15 fibromyalgia patients for an 8-week period with a combination of magnesium (300–600 mg) and malate (1,200–2,400 mg) in a randomized, placebo-controlled, open-label, crossover trial; the treatment group demonstrated improvement in the Tender Point Index scores as well as myalgia symptoms.

Russell et al. assessed the efficacy of Super Malic (containing 200 mg of malic acid and 50 mg of magnesium per tablet, given as 3 tablets twice a day) in the treatment of primary fibromyalgia syndrome; the study included 24 participants with primary fibromyalgia.

A 2021 literature review published in PMC examined this evidence base comprehensively and concluded that magnesium supplementation seems to improve fibromyalgia symptoms, but the level of evidence is still poor.

Evidence assessment: The evidence for magnesium malate in fibromyalgia is limited to small, methodologically heterogeneous trials with high risk of bias. Studies are generally underpowered (n=15–24), and some use open-label designs. No large randomized controlled trials specifically examining magnesium malate (as opposed to magnesium alone or other forms) in fibromyalgia have been conducted. Current evidence is preliminary and insufficient to support firm clinical recommendations.

6.5 Urinary and Kidney Health (Citrate Component)

The citrate component of citrate malate salts has established relevance to kidney stone disease. Among factors relevant to calcium nephrolithiasis, low urine volume, reduced urinary magnesium and citrate concentrations, and unduly acidic or alkaline urine pH are recognized pathogenic contributors. Urinary citrate inhibits the nucleation and growth of calcium oxalate and calcium phosphate crystals by forming soluble complexes with calcium. Citric acid is a strong chelator that inhibits lipid peroxidation and can prevent calcium oxalate kidney stones.

Low concentrations of intestinal calcium have been associated with increased risk of kidney stones and colon cancer; this is probably due to decreased binding and increased absorption of oxalic acid, the main constituent of kidney stones, and of carcinogens such as bile acids. Adequate calcium intake, including from CCM, may thus paradoxically reduce kidney stone risk by binding dietary oxalate in the gut.

6.6 Cardiovascular and Metabolic Health

Research suggests that malate may regulate nitric oxide (NO) production, which plays a critical role in blood vessel dilation and reducing blood pressure, supporting overall cardiovascular function. However, these observations derive largely from in vitro or mechanistic studies, and robust clinical evidence for cardiovascular benefit from citrate malate supplementation specifically is lacking.

A small feasibility study examined the use of effervescent calcium magnesium citrate (a related formulation) in chronic kidney disease patients with cardiovascular risk, in a randomized crossover design. Numerous metabolic disturbances including hyperphosphatemia, high circulating calciprotein particles, hyperparathyroidism, metabolic acidosis, and magnesium deficiency are associated with cardiovascular complications in CKD; the goal of the study was to determine whether effervescent calcium magnesium citrate ameliorates these pathogenic intermediates. This remains a specialized and preliminary area requiring further investigation.

7. Body Systems and Health Areas Associated with Citrate Malate

Skeletal system: Bone mineral density maintenance; prevention of osteoporosis and bone loss in calcium-deficient states (well-supported for CCM).
Muscular and energy systems: TCA cycle anaplerosis; ATP production under aerobic and hypoxic conditions; muscular endurance (primarily citrulline malate, evidence equivocal).
Urinary / renal system: Citrate-mediated inhibition of calcium oxalate crystallization; potential role in kidney stone prevention.
Gastrointestinal system: Organic acid stimulation of gastric secretion; calcium absorption enhancement.
Cardiovascular system: Malate-mediated NO pathway effects on vascular tone (mechanistic evidence, limited clinical data).
Musculoskeletal / rheumatologic: Magnesium malate's proposed role in fibromyalgia (preliminary evidence).
Nervous system / neuromuscular: Via magnesium component in combined magnesium malate preparations.

8. Dosage Forms and Dosages Reported in Studies

The following dosages appear in the cited peer-reviewed and institutional literature. They are reported as found in those sources and are not recommendations.

Calcium citrate malate — bone density in postmenopausal women: 500 mg of elemental calcium per day (as calcium citrate malate) for two years.
Calcium citrate malate — bone density in children: 1,000 mg of calcium citrate malate per day over a three-year trial in children aged 6 to 14 years.
Calcium citrate malate — clinical use (single dose maximum): The maximum dosage of elemental calcium that can be taken in a single dose is 500 mg or less.
Citrulline malate — resistance exercise performance: A single acute 8 g dose of citrulline malate has been the most common approach in studies examining both resistance exercise performance and cycling.
Citrulline malate — high and moderate dose trial: 8 g (CM-MOD) and 12 g (CM-HIGH) doses were compared in a pilot resistance exercise trial.
Citrulline malate — muscle recovery: 6 g of citrulline malate was used in a double-blind crossover recovery study.
Citrulline malate — repeated sprint performance: 8 × 1 g tablets each day (8 g/day total) were taken on the 2 days prior to, and with breakfast on the morning of, each experimental trial.
Magnesium malate — fibromyalgia: A combination of magnesium (300–600 mg) and malate (1,200–2,400 mg) was administered over an 8-week period in a crossover trial.
Magnesium malate (as "Super Malic") — fibromyalgia: Super Malic (containing 200 mg of malic acid and 50 mg of magnesium per tablet) was given as 3 tablets twice a day.

9. Safety Considerations and Known Interactions

9.1 General Tolerability of Calcium Citrate Malate

Calcium citrate malate is generally well tolerated when consumed within recommended ranges. Calcium supplements may contribute to kidney stone formation and gastrointestinal symptoms including constipation and bloating. The citrate component of CCM theoretically mitigates kidney stone risk by increasing urinary citrate, which inhibits calcium oxalate crystal growth — in contrast to the concern about calcium carbonate supplementation increasing urinary calcium without this protective effect.

The absorption kinetics of orally administered calcium depend on the absolute amount of calcium; as the dose of calcium increases, the percentage absorbed decreases. Splitting daily doses is therefore recommended in clinical practice.

9.2 Calcium Interactions with Medications and Nutrients

High protein intakes, specifically of sulfur-containing amino acids, increase urinary calcium excretion; sulfuric acid radicals are believed to decrease renal tubular resorption. However, consumption of high-phosphorus foods such as meat can diminish this effect.

Certain compounds in plants, such as oxalic acid and phytic acid, can decrease calcium absorption by forming indigestible salts with calcium; absorption of calcium is only 5% for spinach, whereas it is much higher, at 27%, for milk. This interaction applies to calcium from CCM consumed alongside high-oxalate foods.

Calcium supplements, including CCM, are known to interfere with the absorption of several drugs when taken simultaneously, including tetracycline and fluoroquinolone antibiotics, levothyroxine, bisphosphonates, and iron preparations. These interactions are attributable to the calcium cation, not to the citrate or malate components specifically.

9.3 Upper Tolerable Intake Levels for Calcium

The dietary reference intakes (DRIs) for calcium were updated in 2010; the RDA is 700 mg/day for children aged 1–3 years, 1,000 mg/day for children aged 4–8 years, 1,300 mg/day for adolescents, 1,000 mg/day for younger adults, 1,200 mg/day for women over age 51, and 1,200 mg for men and women over the age of 70. The Tolerable Upper Intake Level (UL) for calcium set by the Institute of Medicine is 2,500 mg/day for adults aged 19–50 and 2,000 mg/day for those over 50.

9.4 Safety of the Citrate and Malate Anions

Both citrate and malate are endogenous metabolites present in every human cell. Both acids generate alkaline metabolites upon oxidation, and at supplemental doses, both are well characterized as safe food ingredients with a long history of regulatory approval. The FDA recognizes citric acid and malic acid as Generally Recognized as Safe (GRAS). The European Food Safety Authority has evaluated calcium citrate malate as a source for calcium in foods for the general population. In 2007, the EFSA Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food evaluated calcium citrate malate as a source for calcium added to foods for Particular Nutritional Uses, food supplements, and foods intended for the general population.

9.5 Safety of Citrulline Malate

L-Citrulline has a well-established safety profile in human research at doses up to at least 15 g/day in short-term studies. Malic acid at supplemental doses used in citrulline malate (typically 2–6 g as part of the salt) is considered safe, consistent with its GRAS status as a food additive. No serious adverse events have been attributed to citrulline malate in published clinical trials. Mild gastrointestinal discomfort (bloating, nausea) has been reported anecdotally at high doses but has not been systematically characterized in published safety data.

9.6 Regulatory and Quality Considerations

An important analytical finding concerns product quality in commercial citrulline malate preparations. Research using NMR spectroscopy on multiple commercial supplements found that the actual citrulline:malate molar ratio in commercial products did not always match the labeled 2:1 claim. This has methodological implications for interpreting clinical trial results, as inconsistencies in supplement composition confound dose-response analyses.

References

Health Conditions

Health conditions that Citrate malate may help support.

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Body Systems

Body systems that Citrate malate may help support.

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