GABA: What Is It and What Does It Do?

Gamma-aminobutyric acid (GABA) is one of the essential amino acids in the human brain. GABA acts as an inhibitory neurotransmitter, meaning it binds to neurons and hinders their ability to receive or respond to signals from other nerve cells. Without GABA in the brain, the nerves and central nervous system would be extraordinarily overactive and cause conditions like seizures, epilepsy, or mood disorders. However, with too much GABA, one would feel consistently tired or sluggish.

When GABA attaches to a GABA receptor in the brain, it results in producing a calming effect, which can help with feelings of fear, anxiety, or stress. Since GABA is not available from foods other than fermented kimchi, miso, or tempeh, GABA supplements have spiked in popularity.

Because of GABA’s importance, many GABA-related drugs specifically target GABA receptors. These drugs either activate GABA receptors (agonists) or increase the receptors’ sensitivity to GABA (positive allosteric modulators). Both of which increase the effects of GABA in the brain, which lowers neuron activity similar to when someone sleeps. These drugs include many sedatives and tranquilizers like barbital or Valium and Xanax. Alcohol even appears to affect these GABA receptors. However, rather than supply or restrict GABA levels in the brain, these drugs manipulate the sensitivity of GABA receptors.

Concerning GABA supplements, there are conflicting opinions as to whether GABA consumed in food or supplement form can cause any of the beneficial effects of GABA in the brain. This is largely because of the brain’s blood-brain barrier (BBB), which restricts a lot of the molecules that can enter the brain. While some studies say GABA can enter through the BBB, other reviews say either GABA cannot or only small amounts can enter the BBB. This is also why GABA-related drugs do not manage GABA levels, only the sensitivity of GABA receptors.

The first study that investigated GABA and its relationship with the BBB was performed in 1958 and found that GABA could not pass the BBB [1], and later studies confirmed [2] [3] [4]. However, other studies claimed GABA did pass through the BBB but in small amounts [5] [6] [7] [8] [9].

While it may be inconclusive whether GABA supplements influence brain-GABA levels, GABA supplements do seem to affect the enteric nervous system (ENS), which is the nervous system that influences all digestive processes and is not protected behind the BBB. The ENS contains GABA itself and many GABA receptors, and correspondingly, researchers in 2015 proposed that GABA in diet could change GABA levels in the brain in one’s diet through the ENS [10]. So, though we may not know for sure whether GABA directly influences GABA in the brain, there have been numerous studies investigating the clinical benefits of GABA supplementation, and we will review those studies now.

Anxiety and Relaxation

In 2006, researchers investigated and reviewed two studies concerning GABA. In the first study, the researchers examined the anti-anxiety effects of GABA against a placebo, either water or L-theanine [11]. After 60 minutes, the researchers found that the GABA supplementation significantly increased alpha waves and decreased beta waves in the brain, when compared to water or L-theanine. These findings denoted that GABA not only induced relaxation but also reduced anxiety. In the second study, researchers compared a GABA group and a placebo group through a stress test and measured their immunoglobulin A (IgA) levels. The placebo group showed lower IgA levels, while GABA group showed significantly higher levels. After reviewing these two studies, the researchers concluded, “GABA could work effectively as a natural relaxant and its effects could be seen within 1 hour of its administration to induce relaxation and diminish anxiety. Moreover, GABA administration could enhance immunity under stress conditions” [11].

High Blood Pressure

In a 2003, randomized, placebo-controlled, single-blind trial, scientists investigated the blood-pressure-lowering effects of GABA in patients with mild high blood pressure [12]. When compared against the placebo group, there was a significant decrease in blood pressure within 2 to 4 weeks, and the blood pressure remained decreased for the duration of the 12-week study. On average, the mean reduction was 17.4±4.3 mmHg in the systolic BP (SBP) and 7.2±5.7 mmHg in the diastolic BP (DBP), which are the top and bottom blood pressure measurements, respectively [12]. Another 2009, placebo-controlled, double-blind study investigating GABA’s effects on patients with mild high blood pressure had comparable results [13].


In 2018, researchers conducted a randomized, double-blind trial investigating the sleep-aiding effects of GABA supplementation in patients who complained of insomnia symptoms [14]. After four weeks of 300mg/day supplementation, sleep latency decreased, and sleep efficacy increased only in the GABA treatment group. The researchers concluded, “GABA improved not only the subjective sleep quality but also the objective sleep efficacy without severe adverse events” [14].

Fatigue and Stress

Along with studies investigating the GABA-related effects of anxiety and relaxation, researchers have also investigated the GABA-related effects of fatigue and stress.

In a 2011 study, Japanese researchers investigated the effects of beverages containing either 25mg or 50mg of GABA and compared the results [15]. The researchers found that the drinks reduced various measures of mental and physical fatigue while performing a problem-solving task through decreasing levels of chromogranin A (CgA) and cortisol, which are markets of physical exhaustion and fatigue. The two doses, 25mg and 50mg, lowered these levels significantly more than the placebo group’s levels, and the researchers noted the 50mg group had lower mental and physical fatigue measurements than the 25mg group, meaning the higher dose was more efficacious [15].

In a 2009 study, researchers investigated the stress-lowering effects of chocolate containing GABA [16]. Fifteen minutes after the chocolate was eaten, the subjects were assigned an arithmetic task for 15 minutes, and after the job was completed, the researchers measured the patient's heart rate and CgA levels in their saliva. After eating the GABA-infused chocolate, the patient’s heart rate returned quickly to the average level after performing the stressful task, and the patient’s CgA level did not increase. The researchers concluded, “From these results, GABA chocolate was considered to have a psychological stress-reducing effect” [16].

In a 2011 randomized, single-blind, placebo-controlled, crossover-designed study, researchers investigated how GABA effects the mood and central nervous system during stressed conditions caused by mental tasks [17]. With a 100mg dose of GABA, the researchers noted GABA seemed to alleviate the stress induced by mental tasks [17].


While it still may be unclear whether GABA supplementation directly influences GABA levels in the brain, these studies lay the groundwork for future GABA research because they do report various GABA-related benefits such as anxiety, sleep, and stress. It is also important to note these studies are small, and this is primarily due to the fact GABA is a niche and newer supplement that has not had the opportunity to be studied as thoroughly as, let’s say, alpha-lipoic acid.

Nevertheless, many people who use GABA seem to swear by its effects.

If you are interested in trying a GABA product, Healthmasters’ Total Rest product offers 100mg of GABA per serving, along with other ingredients, to support a healthy state of mind.

If you have any questions about Healthmasters’ Total Rest, please feel free to call our office at 800.726.1834.