IngredientsGuanidinoacetic acid (GAA, also known as glycocyamine, betacyamine, or N-amidinoglycine) belongs to the class of organic compounds known as alpha amino acids and derivatives. Glycocyamine (or guanidinoacetate) is a metabolite of glycine in which the amino group has been converted into a guanidine by guanylation — that is, by the transfer of a guanidine group from arginine.
GAA has the chemical formula C₃H₇N₃O₂ and is produced endogenously in the human body from the non-essential amino acids glycine and arginine, in a reaction controlled by the enzyme L-arginine:glycine amidinotransferase (AGAT). The CAS registry number for glycocyamine is 352-97-6, and its molecular weight is 117.11 g/mol.
The compound carries multiple synonyms in the scientific and regulatory literature. These include guanidinoacetic acid, guanidinoacetate, glycocyamine, and betacyamine — all of which refer to the same molecular entity. Guanidinoacetic acid (GAA) is a naturally occurring alpha amino acid derivative and newly recognized dietary compound obtainable by different foods and nutritional supplements.
Guanidinoacetic acid was first prepared synthetically in 1861 by Adolph Strecker by reaction of cyanamide with glycine in aqueous solution. In addition, the recent patent literature describes the synthesis of glycocyamine by catalytic oxidation of ethanolamine to glycine and subsequent reaction with cyanamide in aqueous solution in high yield, analogous to the synthesis of creatine starting from 2-methylaminoethanol via sarcosine.
Regarding its standing in pharmacopeias and regulatory databases: no recorded standards of identity, quality, and corresponding analytical methods for GAA are currently available in the U.S., European, or Japanese pharmacopeias. The European Food Safety Authority (EFSA, 2009) concluded that GAA did not have mutagenic or genotoxic properties. Guanidinoacetic acid is a nutritional feed additive approved by the European Commission for chickens for fattening, weaned piglets, and pigs for fattening.
GAA is synthesized endogenously from non-essential amino acids glycine and L-arginine in the human kidney and pancreas, but could also be obtained from a regular diet. The reaction mainly takes place in the kidney, liver, and pancreas; however, GAA is also produced in the skeletal muscle, brain, and across the gut.
The content of GAA appears to vary across different foods, with meat-based products containing the highest relative amount of GAA (~50 mg per kg), followed by a dairy group (~0.3 mg per kg), and plant-based foods (~1 μg per kg), with the latter considered to be almost negligible. More specifically, the amount of GAA in piglet meat varies from less than 1 mg/kg in the muscle, to 2.2 mg/kg in the liver, and 154 mg/kg in the kidney. In chickens, GAA content fluctuates from 1.8 to 23.7 mg/kg in breast muscle (mean = 9.3 mg/kg).
GAA-containing foods comprise 22.6% of all foods consumed, with the most prevalent dietary sources of GAA being meat-based foods (51.6%), followed by the dairy group (42.6%), and apple (5.9%). The mean dietary intake of GAA was 9.9 ± 9.7 mg per day (95% CI, from 9.6 to 10.1), with the highest consumption recorded in a 50-year-old man at 116.0 mg/day. The dietary exposure to GAA is relatively low among U.S. adults, and the average intake (~10 mg/day) only contributes marginally to the total daily turnover of creatine.
By contrast, dietary supplementation can deliver up to 1,000 mg of GAA per serving, essentially providing up to two orders of magnitude more GAA than a regular omnivore diet. Anecdotal evidence suggests that the GAA exposure from supplements might be a major source of GAA supply, outcompeting other food sources for several orders of magnitude.
According to the NIH Dietary Supplement Label Database (DSLD), a search using synonyms for GAA revealed a total of 118 dietary supplements containing GAA, with the three most recent products added to the database in March 2021. Of the total number of GAA-containing dietary supplements, 82 products were currently available in the U.S. market.
About 85 years ago, Dr. Clarence J. Weber from the University of Kansas School of Medicine was arguably the first to isolate GAA (also known as glycocyamine) from the urine of two patients with pseudo-hypertrophic muscular dystrophy and the urine of normal humans collected during the period of fasting. This seminal work advanced GAA as a regular constituent of normal urine (and serum), and its presence was implied not to be a result of its intake from food but rather an intermediary product in creatine metabolism.
GAA has been investigated as an energy-boosting dietary supplement in humans for more than 70 years. In the 1950s, GAA's use as a therapeutic agent was explored, showing that supplemental GAA improved patient-reported outcomes and work capacity in clinical populations. These early investigations were largely centered in the United States and were driven by an emerging mid-20th-century biochemical understanding of creatine metabolism.
The most substantial body of early clinical work came from the laboratory of Henry Borsook at the California Institute of Technology (Caltech). The group of Henry Borsook from Caltech University demonstrated the beneficial effects of GAA (combined with betaine) in treating cardiac decompensation. The authors treated cardiac patients with a daily dosage of ~70 mg of GAA per kg body weight for up to 12 months.
A series of papers showed that a combination of betaine and guanidinoacetate (glycocyamine) improves the symptoms of subjects with chronic illness, including heart disease, without toxicity. Betaine can provide a methyl group to guanidinoacetate, via methionine, for the formation of creatine. Overall, treatment led to an improved sense of well-being, less fatigue, greater strength and endurance, and increased desire for (and performance of) physical and mental work.
Studies that began in the 1950s showed positive effects of GAA in patients with decompensated heart failure, anxiety (which increases sympathetic activity, overloading the cardiovascular system), and depression. Further, early studies from the 1950s reported beneficial effects of dietary GAA for heart disease (Graybiel and Patterson, 1951; Van Zandt and Borsook, 1951), anxiety (Dixon, Dickel, Shanklin, Peterson, and West, 1954), and acute anterior poliomyelitis (Borsook, Billig, and Golseth, 1962), and promoted GAA for its "creatine recovery effect."
The rationale for combining glycocyamine with betaine was biochemical: a series of studies showed that a combination of betaine and glycocyamine improves the symptoms of patients with chronic illness, including heart disease, without toxicity. Betaine served as a methyl donor to support the conversion of GAA to creatine in the liver, thereby reducing the risk of methyl group depletion that could accompany GAA use alone. The simultaneous intake of methyl-providing substances such as betaine appears advisable because of the risk of homocysteine formation with glycocyamine alone. These clinical applications were not associated with any identifiable indigenous or botanical traditions; glycocyamine's historical use is entirely within the framework of Western biomedical research from the mid-20th century onward.
GAA (chemical formula C₃H₇N₃O₂) is produced endogenously in the human body from non-essential amino acids glycine and arginine, in a reaction controlled by the enzyme L-arginine:glycine amidinotransferase (AGAT). AGAT catalyzes the transfer of an amidino group (–C(=NH)NH₂) from arginine to glycine to synthesize GAA, with ornithine as a byproduct.
In the next step, GAA is combined with S-adenosyl-L-methionine, a reaction catalyzed by guanidinoacetate N-methyltransferase (GAMT), to produce creatine and S-adenosyl-L-homocysteine. The creatine is then released into the bloodstream.
Glycocyamine plays a role in the metabolism of the amino acids serine, threonine, and proline. Additionally, glycocyamine is formed in the mammalian organism primarily in the kidneys by the enzyme L-Arg:Gly-amidinotransferase (AGAT). From L-arginine, ornithine is thus produced, which is metabolized in the urea cycle by carbamoylation to citrulline.
GAA plays several essential roles in the human body, predominantly acting as a direct precursor of creatine, a critical molecular facilitator of cellular bioenergetics. GAA is suggested to effectively increase low levels of tissue creatine and improve clinical features of cardiometabolic and neurological diseases, with GAA often outcompeting traditional bioenergetics agents in maintaining ATP status during stress.
A distinctive aspect of GAA compared to creatine is its route of cellular uptake. This perhaps happens due to a favorable delivery of GAA through specific membrane transporters (such as SLC6A6 and SLC6A13), previously dismissed as untargetable carriers by other therapeutics, including creatine. This difference in transporter usage may explain why, in some studies, GAA proved more effective than creatine itself at raising tissue creatine concentrations.
Even the seminal paper that described the biochemical basis of GAA treatment recognized the possible risk of methyl group depletion following GAA consumption. Since the transformation of GAA to creatine requires a donation of a methyl group (–CH₃) from S-adenosyl-L-methionine, an excessive GAA intake can hypothetically drain the stores of methyl donors in the human body (e.g., methionine, choline, folic acid, B vitamins). The metabolic burden of methyl donor deficiency can perturb many cellular functions, including DNA methylation, neurotransmission, antioxidant defense, and protein synthesis.
The formation of creatine from GAA consumes methyl groups and increases the production of homocysteine. There is also a proposed secondary mechanism: GAA may have the potential to stimulate insulin secretion. Insulin reduces plasma homocysteine and raises methyl group supply. It is possible that the ability of GAA to trigger insulin secretion modulates methyl group metabolism, and comparatively counterbalances the direct effect of GAA on increased methylation demand.
The most developed clinical research domain for glycocyamine/GAA as a dietary supplement involves its use for exercise performance and muscle creatine loading. The pivotal human pilot trial was conducted by Ostojic and colleagues. The study enrolled 48 young participants (age 22.3 ± 1.5 years), who received oral doses of GAA (1.2, 2.4, or 4.8 g/d) for 6 weeks in a randomized, double-blind, placebo-controlled trial. The purpose of this pilot study was to evaluate the effects of supplemental GAA on muscle strength, anaerobic performance, and aerobic performance in healthy men and women.
A separate small crossover trial compared GAA directly with creatine monohydrate as a means of raising tissue creatine levels. In this randomized, double-blind, crossover trial evaluating 4-week supplementation with GAA versus creatine in healthy men (n = 5), GAA (3.0 g/day) resulted in a more powerful rise (up to 16.2%) in tissue creatine levels in vastus medialis muscle, middle-cerebellar peduncle, and paracentral grey matter, as compared with creatine.
A larger superiority trial subsequently examined whether a GAA–creatine combination could outperform creatine alone. A randomized, double-blinded, crossover superiority trial was performed at the University of Novi Sad from December 2016 to November 2017. A total of 14 healthy young men were randomized to receive GAA-creatine mixture (1 gram of GAA and 3 grams of creatine per day) or equimolar creatine (4 grams per day) by oral administration for 4 weeks. Results showed the creatine-GAA mixture was superior to creatine alone for increasing mean creatine levels in skeletal muscle (16.9 ± 20.2 vs. 2.0 ± 6.0%; P = 0.02) and grey matter (5.8 ± 5.3% vs. 1.5 ± 3.2%; P = 0.02), and also for bench press performance (6.0% vs. 5.1%; P < 0.01). Compared with creatine administration alone, combined GAA and creatine resulted in less weight gain (1.6 ± 0.2 kg vs. 0.7 ± 0.2 kg; P < 0.01). No inter-group differences were observed in terms of cardiorespiratory endurance, serum biomarkers, or adverse events.
Evidence strength assessment: The evidence base for GAA as an ergogenic agent is preliminary. Available trials are small (n = 5 to 48), often conducted by overlapping research groups, and some have received partial industry funding. A few studies have examined the safety and efficacy of GAA and suggest potential ergogenic benefits for physically active men and women. Larger, independent replication studies are needed before firm conclusions can be drawn.
Guanidinoacetic acid (GAA), a metabolic precursor of creatine, appears to be a novel energy-enhancing supplement, with GAA being superior to creatine in facilitating creatine concentrations in the human brain and skeletal muscle. The superior brain uptake of GAA compared to creatine is attributed to its use of different membrane transporters, including SLC6A6 and SLC6A13.
In the domain of inherited creatine deficiency disorders, GAA has also been studied. Arginine-glycine amidinotransferase (AGAT) deficiency is a rare inherited metabolic disorder that severely affects brain bioenergetics. Characterized by mental retardation, language impairment, and behavioral disorders, AGAT deficiency is a treatable condition, where long-term creatine supplementation usually restores brain creatine levels and improves its clinical features. In some cases of AGAT deficiency, creatine treatment might be somewhat limited due to possible shortcomings in the performance and transport of creatine to the brain. GAA, a direct metabolic precursor of creatine, has recently been suggested as a possible alternative to creatine to tackle brain creatine levels in experimental medicine.
It is important to distinguish between the therapeutic role of providing exogenous GAA to correct an AGAT deficiency (where GAA is absent or too low) versus the separate and clinically distinct situation of GAMT deficiency, where GAA pathologically accumulates. GAMT deficiency is an autosomal recessive inborn error of creatine synthesis, biochemically reflecting creatine deficiency and a marked accumulation of guanidinoacetate (GAA) in brain and body fluids, which results in a number of physical or mental disabilities, such as global developmental delay/intellectual disability, epilepsy, movement disorders, speech or language delay, and behavioral problems.
Evidence strength assessment: The neurological applications of supplemental GAA remain largely preliminary and preclinical. Clinical use in AGAT deficiency is at a theoretical and early exploratory stage. The population-level trials on brain creatine elevation using MR spectroscopy are small (n = 5–14) and require replication.
The earliest clinical investigation of glycocyamine as a therapeutic involved its use in heart disease. Studies that began in the 1950s showed positive effects of GAA in patients with decompensated heart failure, anxiety, and depression. However, the studies were not able to demonstrate the appearance of atherosclerosis or other cardiovascular impairments.
These early investigations were largely uncontrolled observational or open clinical series, conducted before the modern era of randomized controlled trials. They were typically conducted using a co-administration strategy pairing glycocyamine with betaine in order to supply the methyl donors needed for creatine formation and to prevent homocysteine elevation.
Evidence strength assessment: The cardiac evidence is historical and methodologically weak by modern standards. No rigorously controlled trials have been published since the 1950s specifically evaluating glycocyamine for cardiac indications. The historical data is insufficient to support any definitive cardiological claims.
A pharmacokinetics study in humans examined what happens after a single oral dose. Twenty-four young healthy participants (12 males and 12 females, age 22.3 ± 1.3 years) voluntarily ingested a single dose of GAA (2.4 g) or placebo, followed by serial measurement of serum GAA, creatine, creatinine, and total homocysteine within the next 24 hours. In response to GAA ingestion, a substantial rise in serum GAA and creatine concentration was observed occurring 1 hour after the ingestion (peak value of 144.9 ± 24.8 μmol/L and 65.5 ± 18.6 μmol/L, respectively).
A separate dose-ranging study examined the longer-term metabolic effects of three different doses. The purpose of this study was to investigate the effect of three different dosages of GAA (1.2, 2.4, and 4.8 g/day) administered for 6 weeks on serum and urinary variables related to GAA metabolism. Forty-eight healthy volunteers participated in the randomized, placebo-controlled, double-blind, repeated-measure study. At baseline and after 1, 2, 4, and 6 weeks, participants provided both fasting blood samples and 24-hour urine. GAA intervention significantly increased serum and urinary GAA, creatine, and creatinine as compared to placebo (P < 0.05).
GAA deficiency (as indicated by low serum GAA) has been reported in various conditions, yet this intriguing clinical entity appears to be poorly characterized as yet, either as a primary deficit or as a sequel of secondary disease. This includes kidney and thyroid dysfunctions, neurological diseases and post-traumatic GAA deficit, along with L-arginine:glycine amidinotransferase deficiency, ornithine aminotransferase deficiency, and urea cycle disorders.
Glycocyamine/GAA is available in oral forms, primarily as a powder or encapsulated powder included in pre-workout, muscle-building, and energy-support formulations. The NIH DSLD search revealed a total of 118 dietary supplements containing GAA.
The following dosages have been specifically reported in human clinical or pharmacokinetic studies:
The amount of guanidinoacetic acid (GAA) in nutritional supplements registered in the U.S. National Institutes of Health dietary supplement database varies considerably. Pork and poultry render up to 160 mg of GAA per kilogram of food, while GAA supplements can provide up to 1,000 mg per single serving.
The most studied and substantiated safety concern with supplemental GAA is hyperhomocysteinemia. Preliminary human studies suggest that dietary GAA has a relatively acceptable safety profile, yet medium-term intake appears to provoke unfavorable biochemical abnormalities, such as the rise in serum homocysteine (which could be attenuated by GAA co-ingested with creatine).
However, elevated homocysteine levels have been shown to produce cardiovascular and skeletal problems. A post-marketing surveillance study of the GAA-creatine combination found a different result: 38 individuals (34.2% female) completed the evaluation period. Serious side effects were absent. Two participants (5.3%) reported transitional nausea during the introductory weeks; no participants stopped the treatment. Baseline T-Hcy levels were 11.6 ± 3.1 μmol/L. The intervention induced a mild reduction in T-Hcy levels across the monitoring period (p = 0.028), with T-Hcy levels after 1, 2, 3, and 6 months of 10.4, 10.6, 10.1, and 9.3 μmol/L, respectively.
At low doses, homocysteine does not appear to be problematic. No significant changes in total plasma homocysteine levels were demonstrated during a 17-week study using low-dose GAA (starting at 0.5 g/day), and no cases of GAA-induced hyperhomocysteinemia (T-Hcy >15 μmol/L) were detected among participants with normal baseline T-Hcy levels. These preliminary findings suggest the medium-term safety of supplemental GAA when administered in doses commonly found in dietary supplements.
Since the transformation of GAA to creatine requires a donation of a methyl group from S-adenosyl-L-methionine, an excessive GAA intake can hypothetically drain the stores of methyl donors in the human body (e.g., methionine, choline, folic acid, B vitamins). The metabolic burden of methyl donor deficiency can perturb many cellular functions, including DNA methylation, neurotransmission, antioxidant defense, and protein synthesis. Co-ingestion with a methyl donor such as betaine or creatine has been proposed as a mitigation strategy.
Animal studies reported neurotoxic and pro-oxidant effects of GAA accumulation, with exogenous GAA also appearing to increase methylation demand and circulating homocysteine, implying a possible metabolic burden of GAA intervention. The accumulation of GAA in the brain was also found in children with inborn errors of creatine metabolism, suggesting that extra GAA might contribute to neurological complications in humans, such as epilepsy and seizures. Critically, these neurotoxicity observations are derived primarily from animal studies and from pathological states where GAA cannot be converted to creatine (i.e., GAMT deficiency) — not from dietary supplementation studies in healthy humans. Other adverse events demonstrated in animal studies with non-enteral administration of GAA are not confirmed in human trials with supplemental GAA thus far.
Since the other two creatine deficiency syndromes (AGAT and creatine transporter deficiency) lack extrapyramidal problems, it has been suggested that basal ganglia involvement in GAMT deficiency may arise specifically from the neurotoxic effect of guanidinoacetate.
The co-administration of glycocyamine with betaine or creatine is a pharmacologically significant interaction. Betaine can provide a methyl group to guanidinoacetate, via methionine, for the formation of creatine. As a practical implication, GAA supplements without accompanying methyl donors may increase homocysteine risk, whereas those formulated with creatine or betaine appear to mitigate this concern based on available evidence.
No recorded standards of identity, quality, and corresponding analytical methods for GAA are currently available in the U.S., European, or Japanese pharmacopeias. The end-consumers might be, therefore, exposed to supplemental GAA while being unaware of possible safety issues. The European Food Safety Authority (2009) concluded that GAA did not have mutagenic or genotoxic properties.
The promising effects of dietary GAA might be countered by side-effects and possible toxicity. GAA is suggested to effectively increase low levels of tissue creatine and improve clinical features of cardiometabolic and neurological diseases, with GAA often outcompeting traditional bioenergetics agents in maintaining ATP status during stress. The overall safety profile observed in short- to medium-term human studies is relatively acceptable when GAA is used at doses consistent with those found in dietary supplements, particularly when co-administered with creatine. Dose-dependent hyperhomocysteinemia remains the most clinically relevant and evidence-supported concern at higher doses used alone. Long-term safety in humans has not been established through rigorous, large-scale trials.
Health conditions that Glycocyamine may help support.
Body systems that Glycocyamine may help support.
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