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This essential neurotransmitter may be associated with a number of neurological and mental health conditions.

Otherwise known as gamma-aminobutyric acid, GABA is an amino acid produced in the brain that acts as a neurotransmitter. “It facilitates communication among brain cells,” says Michael J. Breus, Ph.D., “The Sleep Doctor,” a clinical psychologist and both a Diplomate of the American Board of Sleep Medicine and a Fellow of The American Academy of Sleep Medicine.

He explains that GABA’s main function is to reduce the activity of neurons in the brain and central nervous system (which includes the brain and spinal cord). “It has the effect of moving the brain and the body into lower gear,” continues Breus. As a result, research indicates GABA can help promote relaxation.

“By inhibiting neural activity, GABA facilitates sleep, reduces mental and physical stress, lowers anxiety and creates a calmness of mood,” he adds. Furthermore, Breus states that GABA may also encourage improved immunity and gut health, as well as a better functioning metabolism.

“The significance of this key neurotransmitter has been recognized only in recent years, but it is now suspected to play a role in a multitude of health conditions, including ADHD, inflammation, and premenstrual syndrome,” says Josh Axe, D.N.M., C.N.S., D.C., founder of Ancient Nutrition.

Even though some foods either naturally contain this amino acid (such as green, black, and oolong tea, along with fermented foods, like miso and tempeh) or boost its production (including mushrooms, tomatoes, spinach, broccoli, oat, wheat, brown rice, and sweet potato) according to the Cleveland Clinic and a review published in the journal Nutrients, GABA is also available as a dietary supplement.

Dietary supplements are products intended to supplement the diet. They are not medicines and are not intended to treat, diagnose, mitigate, prevent, or cure diseases. Be cautious about taking dietary supplements if you are pregnant or nursing.

While blood tests cannot indicate a GABA deficiency, decreased levels of GABA could be linked to certain symptoms and health conditions, including:

Data indicates that research on the effectiveness of GABA capsules is limited, yet below are some of the most common uses for this supplement:

“One of the main functions of GABA is to reduce nerve excitability, which could be linked to feelings of anxiety and fear,” says Axe. “In fact, certain anxiety disorders have even been associated with decreased levels of GABA.” One study involved 13 volunteers who underwent an EEG (electroencephalogram, a test which records electrical activity in the brain) one-hour after taking a GABA supplement. The researchers from Japan noticed that the non-invasive test revealed that the participants’ experienced significantly increased alpha waves (which shows relaxation), as well as decreased beta waves (which indicates a less awakened state).

Another study published in the same journal as the previous research focused on eight adults who suffered from acrophobia (a fear of heights) and were instructed to cross a suspended bridge. The volunteers who were given GABA showed significantly higher levels of Immunoglobulin A (IgA) levels in their saliva compared to the placebo group, indicating that the supplement may enhance immunity under stressful conditions.

Reduced levels of GABA have been linked to disrupted sleep, along with trouble falling and/or staying asleep, says Breus. In one study published in the journal Sleep, individuals living with insomnia had approximately 30% lower GABA activity compared to those who didn’t suffer from this disorder. “Plus, low GABA levels also corresponded to more restless, wakeful sleep,” he says.

Breus refers to a study conducted in Korea that suggests a combination of GABA and 5-hydroxytryptophan (also known as 5-HTP, a compound made in the body that produces serotonin, a neurotransmitter that plays a role in sleep-wake cycles, along with mood, digestion, and sexual desire) could improve sleep quality and increase sleep time. “Given the importance of GABA to the body’s sleep patterns, more research into the effects of GABA supplements on sleep is sorely needed.”

An article published in the journal Nutrients stated that some evidence points to a moderate drop in blood pressure after taking a GABA dietary supplement. In a 12-week study comprised of 80 adults with borderline hypertension, volunteers were recorded having significantly lower blood pressure readings after consuming a chlorella supplement, a GABA-rich type of algae. “In addition to being important on its own, maintaining a healthy blood pressure can also help protect your sleep,” states Breus.

“Although inflammation is a normal response triggered by the immune system as a result of illness or injury, chronic inflammation can contribute to diseases like arthritis, heart disease, and cancer,” says Axe. A review published in the Journal of Neuroinflammation theorizes that GABA may reduce the activity of a pathway that triggers joint inflammation in rheumatoid arthritis, he explains. Also, a research paper published in the peer-reviewed journal EBioMedicine suggests that not only might GABA help regulate the release of both pro- and anti-inflammatory cytokines (small proteins) in adults living with type 1 diabetes, but targeting GABA signaling could be the key in finding a cure for types of diabetes.

Muscle pain and headaches could be symptoms of low GABA levels, states Breus. According to a 12-week study conducted by researchers from Japan, healthy men between the ages of 26 and 48 who performed resistance training exercises, such as leg presses, leg extensions, and leg curls, twice a week experienced enhanced muscular hypertrophy (meaning muscle growth) after taking post-workout GABA supplementation with whey protein.

Breus says possible side effects include:

The United States Pharmacopeia (USP)—an independent, non-profit organization that sets quality, purity, strength, and identity standards for medicines, food ingredients, and dietary supplements—conducted a safety evaluation of GABA supplements and their results showed no serious side effects associated when consuming 120 milligrams daily for 12 weeks, as reported in an article published in Nutrients. Doses vary based on age, sex and weight, states Axe. “Before starting supplementation, it’s best to talk to your doctor and determine if it’s right for you as well as how much you should take.”

Axe warns that pregnant and breastfeeding women should refrain from taking GABA since studies have yet to be conducted. And lastly, both doctors add that GABA may interfere with prescription medications that treat high blood pressure, depression, anxiety, and insomnia.