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What is GABA? - Function, Benefits & Side Effects

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  • 0:01 GABA as a Neurotransmitter
  • 2:03 GABA as a Supplement
  • 5:33 Lesson Summary
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Lesson Transcript
Instructor: Jay Mallonee

Jay is a wildlife biologist, college professor and writer. His master's degree is in neurobiology and he has studied animal behavior since 1976.

GABA is a common neurotransmitter in the brain and is also used as a medicinal supplement to help reduce anxiety in some people. However, its effects are controversial. Does GABA actually reduce anxiety or not? Judge for yourself.

GABA as a Neurotransmitter

Your brain is composed of trillions of nerve cells, some of which can produce impulses. These cells are called neurons. When they communicate with one another, circuits are formed which allow you to think, feel, and function properly in response to your surroundings. Unlike in computers, this circuitry is alive and can change on its own over time. Therefore, it is responsive to surrounding chemicals. For example, the neurons that comprise a circuit don't actually touch, but instead are separated by tiny gaps called synapses. Specific molecules or compounds, known as neurotransmitters, are released by a neuron (presynaptic) on one side of the synapse and float across the gap to communicate with the next neuron in line (postsynaptic). The neurotransmitters literally fit into receptor sites, like a docking station for space craft, and either begin another impulse in the postsynaptic neuron or prevent it.

In the mammalian brain, which includes humans, there are two main neurotransmitters: Glutamate and GABA (gamma-aminobutyric acid). Glutamate is excitatory, which means that when it fits into its corresponding receptor sites a new impulse is initiated in the postsynaptic neuron. When GABA fits into its receptor sites, the production of a new impulse is prevented and, therefore, has an inhibitory effect. The interaction between GABA and glutamate provides a stable and balanced emotional environment for the brain under normal conditions. Because of its inhibitory characteristic, GABA has become a popular medicinal supplement for people that suffer from excessive anxiety. The presumption is that GABA will help suppress the circuits in the brain that are causing the anxiety. But does it work? Ingesting GABA orally doesn't necessarily mean it will ultimately end up in the brain, and if it does, are there any side effects?

GABA as a Supplement

The nutrient supplement industry makes two important claims about the effects of GABA when ingested orally:

  1. GABA reduces anxiety by suppressing the circuitry in the brain that causes the anxiety
  2. GABA increases growth hormone secretion, thus increasing muscle mass

Let's look at each of these claims and see if they are true, starting with suppressing anxiety.

Your body is designed to take good care of your central nervous system (CNS), which consists of your brain and spinal cord. The main mechanism is the blood brain barrier. Your CNS is surrounded by a tough membrane that contains very small blood vessels called capillaries. In many areas of the body, capillaries exchange substances contained in the blood with surrounding tissues, such as oxygen and glucose. The same occurs in the brain but is highly regulated. These particular capillaries are surrounded by cells that are packed tightly together.

Therefore, only certain substances can pass through, thus creating a barrier of sorts that helps to protect the CNS. When it comes to GABA, it is already produced within the brain and used as a neurotransmitter. If you were to ingest a GABA supplement, it would have to pass through the blood brain barrier to reach the brain. Does it? Mostly no. It does so at very low levels, which means the barrier blocks the majority of GABA from reaching the brain. Therefore, It appears that GABA supplements don't really reduce the activity of brain circuits responsible for increased anxiety. However, more studies are necessary to know for certain.

Let's see if it works at causing the secretion of growth hormones.

This hormone is located in the Anterior pituitary of your brain. When secreted into the bloodstream, it causes an increase in muscle tissue production. Body builders and other athletes exploit this process by consuming growth hormone supplements. However, the supplements enter the bloodstream directly and don't require simulation of the pituitary gland.

For GABA to produce the same effect, in theory, it would have to pass through the blood brain barrier to even reach the pituitary gland. Of course not much gets there, yet some muscle mass increase has been documented when GABA supplements are used. So what's happening? It turns out that growth hormone has over 100 different forms that can float through the bloodstream at any given moment, a few of which GABA can interact with. So, when GABA supplements enter the bloodstream, these reactions can cause a slight increase in growth hormone production. The result can be increased muscle mass over time.

Now, let's look at the potential side effects.

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