Benefits
Higher creatine levels in tissues
In small trials from one research group, GAA taken for 4 weeks to 3 months raised creatine in thigh muscle and several brain regions. In 21 women taking 2.4 g a day for 3 months, muscle creatine rose 36% versus 2% on placebo. Brain results varied by region: in 5 men, thalamus creatine fell after 4 weeks while other regions rose.
Grip strength and upper-body muscular endurance
In a 6-week placebo-controlled trial in 48 young adults, handgrip strength improved more than placebo at 1.2 and 2.4 g a day, and bench press repetitions at 1.2 and 4.8 g a day, with no dose-response pattern. In an 8-week pilot in 21 adults aged 65 and over, handgrip rose with 2 g of GAA but not with creatine; there was no placebo group and confidence intervals were wide.
Physical performance tests in adults aged 65 and over
In a placebo-controlled crossover pilot in 21 healthy adults aged 65 and over, 8 weeks of 2 g GAA plus 2 g creatine a day improved gait speed, sit-to-stand and Timed Up and Go results more than placebo and raised muscle and brain creatine. Cognitive screening and quality-of-life scores did not differ. With creatine in the mix, the effect cannot be credited to GAA alone.
GAA with creatine compared with creatine alone
In a 4-week crossover in 14 healthy young men, 1 g of GAA plus 3 g of creatine a day raised muscle creatine by about 17% versus 2% with 4 g of creatine alone, and gray matter creatine by about 6% versus 2%, with slightly better bench press results and less weight gain. Endurance, blood markers and side effects did not differ between the two.
Reaction time on a word recognition test
In a 6-week placebo-controlled trial in 58 healthy, active adults, GAA (2 g a day) plus creatine (10 g a day) gave faster reaction times than placebo on one delayed word recognition test. GAA alone only trended toward faster responses. Picture recognition, vigilance, spatial memory and Stroop tests showed little or no effect, so this is not evidence of better thinking overall.
Fatigue scores and exercise capacity
In a 3-month placebo-controlled crossover in 21 women with chronic fatigue syndrome, 2.4 g of GAA a day did not change the main outcome, general fatigue, or muscle pain. Muscle creatine rose, and changes in strength and aerobic power were greater than with placebo. This is one small trial in a patient group, not evidence for everyday tiredness.
Mechanism of action
One methylation step from creatine
GAA is the direct precursor of creatine. The enzyme GAMT, mainly in the liver, moves a methyl group from S-adenosylmethionine (SAMe) onto GAA to make creatine, which is then released into the blood and taken up by tissues through a specific transporter. The by-product of this step is broken down into homocysteine.
Methyl-group demand and homocysteine
Each GAA molecule needs a methyl group to become creatine, so extra GAA increases demand on the methylation cycle, which produces homocysteine as a by-product. In trials, fasting homocysteine rose with GAA alone, serum B vitamins did not fall over 6 weeks, and methyl donors given alongside limited the rise.
Blood levels rise faster than the dose
After single oral doses of 1.2, 2.4 or 4.8 g in 48 volunteers, blood GAA exposure rose more than in proportion to the dose, and plasma creatine rose 80%, 116% and 293% above placebo. Elimination half-life was under 1.75 hours at the two lower doses and over 2.1 hours at the highest.
Clinical trials
Randomized, double-blind trial comparing GAA 2.4 g/day alone with GAA plus methyl donors (1.6 g/day betaine HCl, 5 µg vitamin B12, 10 mg vitamin B6, 600 µg folic acid) for 8 weeks (registered NCT01371357). Supported in part by an Alzchem grant; Alzchem supplied the formulation and one co-author worked at Alzchem. (Ostojic et al. 2013, Br J Nutr)
20 healthy men and women.
Serum and urine creatine rose in both groups. Hyperhomocysteinemia (high homocysteine) developed in 55.6% of those on GAA alone and in no one on GAA plus methyl donors (P = 0.01). Minor adverse events were 33.3% versus 10.0% (P = 0.30). Very small, no placebo arm; it compares two GAA regimens.
Randomized, double-blind, placebo-controlled pilot trial of GAA at 1.2, 2.4 or 4.8 g/day for 6 weeks, testing strength, anaerobic and aerobic performance. Its size, doses and participant ages match registered trial NCT01133899, funded by an Alzchem grant, whose blood and urine results appear in two other papers listed under References. (Ostojic et al. 2015, J Investig Med)
48 young men and women (mean age 22.3).
Handgrip strength improved more than placebo at 1.2 and 2.4 g/day, and change in bench press repetitions was greater than placebo at 1.2 and 4.8 g/day; there was no dose-response pattern. The abstract gives no aerobic or anaerobic results. In the same trial's blood-marker report, fasting homocysteine rose by an average of 3.5 µmol/L in the GAA groups and serum B vitamins did not change. The authors call the study preliminary.
Randomized, double-blind, placebo-controlled crossover trial of GAA 2.4 g/day or cellulose placebo for 3 months each, with a 2-month washout. (Ostojic et al. 2016, Nutrients)
21 women aged about 39 meeting 1994 CDC criteria for chronic fatigue syndrome.
No effect on the primary outcome (general fatigue on the Multidimensional Fatigue Inventory) or on musculoskeletal pain at rest or during activity. Muscle creatine rose 36.3% with GAA versus 2.4% with placebo, and changes in muscular strength and aerobic power were greater with GAA. A creatine and work-capacity signal without a change in the main symptom.
Randomized, double-blind, crossover superiority trial of 1 g GAA plus 3 g creatine per day versus 4 g creatine per day for 4 weeks (registered NCT03350282, sponsored by the University of Novi Sad; the senior author has disclosed an Alzchem advisory role and Alzchem research funding). (Semeredi et al. 2019, Nutrition)
14 healthy young men.
The mixture raised skeletal muscle creatine 16.9% versus 2.0% with creatine alone (P = 0.02) and gray matter creatine 5.8% versus 1.5% (P = 0.02), with a small edge in bench press (6.0% vs 5.1%) and less weight gain. Endurance, serum markers and adverse events did not differ. Large spread in the muscle results (plus or minus 20.2%) in a very small sample.
Randomized, double-blind, placebo-controlled crossover pilot trial (published as a letter) of 2 g GAA plus 2 g creatine per day versus inulin placebo for 8 weeks, with a 4-week washout (registered NCT04652921). (Seper et al. 2021, Ann Nutr Metab)
21 healthy adults aged 65 and over (mean age 69.6, 13 women).
The mixture improved gait speed, five-times sit-to-stand and Timed Up and Go results more than placebo and raised muscle and brain creatine on MR spectroscopy. Cognitive screening (MoCA) and sarcopenia quality-of-life scores did not differ. Serum creatinine rose 19.3% versus 14.3% on placebo, with no values above clinical thresholds. The paper reports no external funding; the senior author disclosed ties to creatine and GAA companies including Alzchem.
Double-blind, randomized, placebo-controlled trial of placebo, GAA 2 g/day, or GAA 2 g/day plus creatine monohydrate 10 g/day for 6 weeks, described by the authors as a proof-of-concept exploratory trial (ISRCTN68542582). (Chun et al. 2026, J Int Soc Sports Nutr)
58 healthy, active adults (33 women, mean age 35.5).
Significant group-by-time effects for overall and YES reaction time on the delayed word recognition test came from the GAA plus creatine group versus placebo; GAA alone only trended toward faster overall reaction time (p = 0.10). Picture recognition, digit vigilance, Corsi block and Stroop tests showed limited or no effect. No clinically meaningful changes in blood markers or side effects. Funded by the WoodNext Foundation; Alzchem donated the supplements and funded the homocysteine assays, and the senior author is a paid consultant to the chair of Alzchem's scientific advisory board.
Randomized, double-blind, exploratory pilot trial of GAA 2.0 g/day versus an equimolar dose of creatine monohydrate for 8 weeks, without structured exercise. (Todorovic et al. 2026, J Nutr Sci Vitaminol (Tokyo))
25 healthy adults aged 65 and over randomized; 21 completed (11 GAA, 10 creatine).
Handgrip strength rose with GAA but not creatine (time-by-treatment P = 0.04; Hedges' g 0.91, 95% CI 0.00 to 1.81). GAA was linked to within-group rises in fat-free mass, muscle mass and body water, with wide confidence intervals. No adverse events. The authors call the findings preliminary and hypothesis-generating; there was no placebo arm. No external funding; the senior author reports creatine-related research collaborations, consulting and intellectual property.