The GAD Gene Pathway and Balance

In the complex world of genetics and biochemistry, certain genes and pathways influence our health in ways we may not always see.

One of these is the GAD pathway.

GAD stands for glutamic acid decarboxylase. It plays an important role in the balance between glutamate and GABA, two neurotransmitters involved in how the nervous system responds to stimulation, stress and the environment around us.

I find myself discussing this pathway with many of my clients, especially those who feel anxious, overstimulated, tired but wired or unable to settle. My hope is that this post helps explain the pathway without making it more complicated than it needs to be.

The GAD pathway

Glutamate is the primary excitatory neurotransmitter in the brain. It helps neurons communicate and is necessary for learning, memory and normal brain function.

GABA, or gamma-aminobutyric acid, is the primary inhibitory neurotransmitter. It helps reduce excessive neuronal firing and acts as part of the nervous system’s braking system.[1]

The body uses glutamic acid decarboxylase enzymes to convert glutamate into GABA.

These enzymes are produced primarily by two genes:

• GAD1 produces the GAD67 enzyme.

• GAD2 produces the GAD65 enzyme.

  
  

GAD67 is involved in maintaining baseline GABA production, while GAD65 is more active around nerve terminals and helps provide GABA when neuronal activity increases.[2,3]

We need both sides of this system. Glutamate is not bad and GABA is not good. Too much inhibition is no healthier than too much excitation. The goal is the ability to move between activation and rest without becoming stuck in either state.

What does a GAD gene variant mean?

Genetic variations in GAD1 and GAD2 have been studied in relation to brain function, GABA concentrations, anxiety and several neurological or psychiatric conditions.[3–5]

That does not mean that having a common GAD SNP proves someone has low brain GABA or excessive glutamate. Most common variants have relatively small effects and their significance may depend on sex, other genes, health history and environmental influences.

A genetic report shows potential susceptibility. It does not measure GAD enzyme activity, glutamate levels or GABA inside the brain.

GAD1 expression may also be influenced by epigenetic regulation, including DNA methylation. Most of this research has been conducted in brain tissue and in connection with serious neurological or psychiatric conditions. It should not be interpreted to mean that a common SNP automatically creates a generalized “methylation problem.”[3,6]

Where gluten may fit

Gluten is a protein found in wheat, barley and rye. In people with celiac disease, gluten triggers an autoimmune response that damages the small intestine. Celiac disease can also have neurological and psychiatric manifestations, including neuropathy, headaches, cognitive changes and ataxia.[7,8]

A smaller group of people may experience non-celiac gluten sensitivity. They can have gastrointestinal or neurological symptoms related to wheat or gluten without meeting the diagnostic criteria for celiac disease. This area remains more difficult to define and not every symptom that improves on a gluten-free diet is necessarily caused by gluten itself.

There is also a rare but important distinction between GAD gene variants and GAD antibodies.

Anti-GAD antibodies are autoimmune antibodies directed against glutamic acid decarboxylase. They are associated with conditions such as type 1 diabetes, stiff-person syndrome and certain autoimmune neurological disorders. Research has identified an overlap between gluten-related neurological disease and anti-GAD-associated ataxia in a small, specialized group of patients.[9,10] This is not the same as having a common GAD1 or GAD2 SNP.

The available evidence does not show that gluten routinely blocks the GAD enzyme in everyone with anxiety, digestive problems or a GAD variant. A gluten-free diet is essential for confirmed celiac disease and may be useful for carefully evaluated gluten sensitivity, but it is not an established treatment for every GAD SNP. Anyone who may have celiac disease should be tested before removing gluten. Blood tests and intestinal biopsies can become falsely negative after gluten has been eliminated.[11]

Gluten and the individual person

Although I would not recommend a gluten-free diet based on a GAD SNP alone, I may consider a structured trial when the person has:

• Digestive symptoms connected to wheat or gluten.

• A personal or family history of celiac disease or autoimmunity.

• Iron, folate or B12 deficiencies without a clear explanation.

• Dermatitis herpetiformis.

• Migraines, neuropathy or neurological symptoms that appear connected to gluten exposure.

• Symptoms that improve with removal and return with a careful rechallenge.

  
  

After appropriate celiac testing, gluten may be removed for a defined period while symptoms are tracked. It is important to look for improvement in digestion, energy, sleep, mood, pain and cognitive clarity.

The rechallenge matters. Without it, we cannot always tell whether the improvement came from removing gluten, reducing processed food, eating fewer fermentable wheat carbohydrates or changing the diet in another way.

L-theanine and nervous system support

L-theanine is a naturally occurring amino acid found primarily in tea leaves. It is known for supporting a relaxed but alert state without usually causing significant drowsiness.

Animal research suggests that L-theanine may influence GABA, glutamate, dopamine and serotonin signaling. It also interacts with glutamate receptors. Human studies provide some support for reducing perceived stress and supporting relaxation, attention and sleep.[12–14]

What we cannot say is that L-theanine bypasses a defective GAD gene or directly corrects a genetically impaired glutamate-to-GABA conversion pathway. That has not been demonstrated in humans. I prefer to think of L-theanine as a tool that may support overall neurotransmitter balance and help settle an overstimulated nervous system. It is not a replacement enzyme and it does not erase a genetic variant.

Practical ways to support this pathway

1. Test before removing gluten

If celiac disease is possible, complete testing while gluten is still being eaten. Once celiac disease has been reasonably excluded, a structured gluten-free trial may be considered when the symptom pattern supports it. During the trial, focus on whole foods rather than replacing every gluten-containing product with highly processed gluten-free products. Vegetables, fruit, quality proteins, healthy fats and naturally gluten-free carbohydrates can provide a strong foundation.

At Restored Wellness, we use our RESET Plan to help people temporarily remove common inflammatory foods while learning how to build balanced meals and support steady blood sugar. It will be available on our website soon.

2. Consider L-theanine

L-theanine is naturally present in green tea and matcha. These also contain caffeine, so they may not be appropriate for someone who is already anxious, sensitive to stimulants or struggling with sleep.

Supplemental L-theanine allows for a more consistent amount without the caffeine. Human studies have commonly used approximately 200 to 400 mg per day, although I prefer to begin lower and assess the individual response.[13] Someone taking medication, dealing with low blood pressure, pregnant or breastfeeding should discuss its use with an appropriate healthcare professional.

3. Support the nutrients involved

The GAD enzymes require pyridoxal-5′-phosphate, the active form of vitamin B6, as a cofactor. Magnesium also supports normal nerve signaling and the balance between excitatory and inhibitory activity. This does not mean everyone needs a high-dose B complex or large amounts of supplemental B6. Long-term excessive B6 can cause sensory neuropathy. Nutrient support should be based on diet, symptoms, medications and appropriate testing.

4. Make room for stillness

Quiet time, prayer, deep breathing, grounding and walking outside may help move the body away from a constant fight-or-flight response. These practices are not about pretending that physical symptoms are mental. They affect real autonomic and neurological pathways. The nervous system needs repeated experiences of safety, not simply another supplement.

5. Pay attention to patterns

Notice changes in sleep, mood, digestion, sensory sensitivity, tension and the ability to recover after stress. Improvement does not prove that a GAD SNP was the cause. It tells us that the intervention may be supporting the person and gives us information about what to do next.

The GAD pathway is an important part of how the brain maintains a balance between stimulation and inhibition. Genetics may influence this pathway, but genes are only one part of the picture.

Sleep, blood sugar, inflammation, nutrient status, hormones, gut health, medications, trauma and ongoing stress can all affect how the nervous system functions.

The goal is not to diagnose low GABA from a genetic report. It is to understand the person in front of us, identify what may be keeping the nervous system on alert and choose support that fits the individual.

For some people, that may include removing gluten after appropriate testing. For others, gluten may have nothing to do with the problem. L-theanine may offer useful support for stress and relaxation, but it should not be presented as a cure for a GAD variant.

Genetics can help us ask better questions. It should not cause us to assume we already have all the answers.

Citation Guide

1. Cleveland Clinic. Gamma-aminobutyric acid (GABA): Function and relationship with glutamate.Read the overview

2. NCBI Gene. GAD1: Glutamate decarboxylase 1. National Library of Medicine.View the gene record

3. Tao R, Li C, Newburn EN, et al. GAD1 alternative transcripts and DNA methylation in human prefrontal cortex and hippocampus in brain development, schizophrenia and bipolar disorder. PLoS One. 2018.Read the study

4. Weber H, Scholz CJ, Domschke K, et al. Gender differences in associations of glutamate decarboxylase 1 gene variants with panic disorder and dimensional anxiety measures. PLoS One. 2012;7(5):e37651.Read the study

5. Colic L, et al. GAD65 promoter polymorphism rs2236418 modulates harm avoidance and brain GABA concentrations in interaction with sex. Frontiers in Behavioral Neuroscience. 2018.Read the study

6. Pearson G, et al. DNA methylation profiles of GAD1 in human cerebral cortex. International Journal of Molecular Sciences. 2022;23(16):9188.Read the study

7. Giuffrè M, et al. Celiac disease and neurological manifestations: From gluten to neuroinflammation. 2022.Read the review

8. Jackson JR, Eaton WW, Cascella NG, Fasano A, Kelly DL. Neurologic and psychiatric manifestations of celiac disease and gluten sensitivity. Psychiatric Quarterly. 2012;83(1):91–102.Read the review

9. Hadjivassiliou M, et al. GAD antibody-associated neurological illness and its relationship to gluten sensitivity. Acta Neurologica Scandinavica. 2011;123(3):175–180.View on PubMed

10. Hadjivassiliou M, et al. Clinical characteristics and management of 50 patients with anti-GAD ataxia: Gluten sensitivity and immunological overlap. Cerebellum. 2021.Read the study

11. American College of Gastroenterology. Celiac disease: Diagnosis and testing.Read the clinical guidance

12. Nathan PJ, Lu K, Gray M, Oliver C. The neuropharmacology of L-theanine. Journal of Herbal Pharmacotherapy. 2006;6(2):21–30.View on PubMed

13. Williams JL, Everett JM, D’Cunha NM, et al. The effects of green tea amino acid L-theanine consumption on the ability to manage stress and anxiety levels: A systematic review. Plant Foods for Human Nutrition. 2020;75(1):12–23.View on PubMed

14. Hidese S, Ogawa S, Ota M, et al. Effects of L-theanine administration on stress-related symptoms and cognitive functions in healthy adults: A randomized controlled trial. Nutrients. 2019;11(10):2362.Read the study