You finally committed to following a clean, whole-foods-based diet. You’re working on your gut health like everyone says you should.

You picked up the detox-friendly food list, cleared your pantry of anything ending in -itos or -oodles, and stocked up on probiotic-rich foods and gut-repairing supplements.

You start your day like a health optimization champ: a protein-forward breakfast, a glass of lemon water, your full stack of supplements—and of course, a hefty scoop of L-glutamine because everybody says it’s amazing for gut health.

And then it hits you.

Not energy.

Not clarity.

But rage.

You’re short-tempered, irritable, and irrationally angry about things that normally wouldn’t faze you.

The barista took too long? That’s it—you’re fuming. Your spouse left a dish in the sink? You’re ready to start Googling divorce lawyers. Even your dog breathing too loudly seems like a personal attack.

You don’t want to admit it, but you’re suddenly turning into the Incredible Hulk—with collagen creamer and gut supplements.

What gives?

When Gut Healing Goes Off the Rails

If you’re experiencing this strange twist—trying to do something good for your gut but ending up with the temperament of a caffeinated honey badger—you’re not crazy.

And you’re definitely not alone.

It could be your glutamine.

More specifically, how your brain and nervous system are responding to your new flood of glutamine—an amino acid that plays a key role in gut repair, immune health, and even brain function.

For most people, glutamine is incredibly beneficial. But for a small subset of people, especially those with specific genetic variations or neurotransmitter imbalances, too much glutamine can turn up the volume on their nervous system, leading to anxiety, restlessness, irritability, or even aggression.

Let’s dig into the science of how this happens.

What Is Glutamine, Anyway?

Glutamine is the most abundant amino acid in your body. Your muscles, brain, and gut all use it like it’s going out of style.

In your gut, it’s a critical fuel source for your intestinal cells, helping to repair leaky gut, reduce inflammation, and support immune function. That’s why you see it recommended in every gut-healing protocol known to man.

In your brain, however, glutamine is a precursor to neurotransmitters.

And this is where things get interesting (and sometimes uncomfortable).

Glutamine is converted into glutamate, which is your brain’s primary excitatory neurotransmitter.

You need glutamate to focus, stay alert, and get things done. But when you have too much glutamate—or your body has trouble converting it into calming neurotransmitters like GABA—things can go sideways fast.

Glutamate vs. GABA: The Yin and Yang of Your Brain

Think of glutamate as the gas pedal and GABA as the brakes.

When you’re in balance, you accelerate when needed (glutamate), and you can slow down and relax (GABA).

But if you’re adding extra glutamine and your brain is already tilted toward high glutamate activity—or you’re not converting it well into GABA—you’re slamming the gas pedal without any brakes.

Cue the road rage. Or fridge rage. Or mild-mannered-text-message-from-your-mother rage.

This is especially common in people with:

• MTHFR mutations (which affect methylation and neurotransmitter balance)
• Low GABA levels or GAD gene variants (which impair GABA synthesis)
• COMT mutations, which can impair the breakdown of stimulating neurotransmitters
• High stress lifestyles (hello, cortisol rollercoaster)
• Poor sleep or overuse of stimulants

So... Should You Ditch Glutamine?

Not necessarily.

For most people, glutamine is one of the most effective, inexpensive, and science-backed supplements for gut repair, especially post-antibiotics, after hard training, during illness recovery, or when trying to reverse leaky gut.

It:

• Repairs and strengthens the intestinal lining
• Helps regulate immune response
• Supports blood sugar balance
• Reduces sugar cravings
• Helps muscle recovery and even post-surgery healing

But if you’re among the sensitive few, you may need to go slower—or support your neurotransmitter balance first.

What to Do If Glutamine Makes You Feel Like You Could Punch a Hole in the Wall

Here’s what I recommend:

1. Start low and slow. Try 1–2 grams at first instead of the typical 5–10 grams. Gauge how you feel.

2. Take it away from other stimulating supplements. Don’t stack it with caffeine, pre-workouts, or nootropics until you know how your body reacts.

3. Take it at the right time. For gut healing, glutamine is best first thing in the morning or between meals—on an empty stomach.

4. Support GABA production. Supplement with magnesium glycinate, L-theanine, taurine, or even GABA itself (if tolerated) to balance the excitatory effects.

5. Eat for neurotransmitter health. Get plenty of B6, magnesium, zinc, and protein to help your brain stay balanced.

6. Consider your genetics. If you know you have MTHFR, COMT, or GAD variants, be especially cautious. Glutamine may still work for you—it just may need more support.

Glutamine Isn’t the Villain

If you had a strange reaction to glutamine, it’s not because it’s a bad supplement. It’s because you’re biochemically unique—and that’s something worth celebrating, not fearing.

For 90% of people, glutamine is one of the best things they can take for gut repair, immune resilience, and post-workout recovery.

In fact, I recommend LTH Repair L-Glutamine (if you're in the U.S.) because:

• It’s pure, pharmaceutical-grade
• It mixes easily and is unflavored
• It comes from a trusted, quality-tested source
• And it's the exact same kind I use myself and recommend to clients

But if you’re the person who got hit with a surprise wave of Hulk-mode while trying to fix your gut—take heart.

You’re not broken. You’re not crazy. You’re just wired a little differently.

And now you know.

Support your gut, support your brain, and get back to healing—without needing an anger management coach.

👉 Click here to try LTH Repair L-Glutamine (U.S. only).

Your gut—and everyone around you—will thank you.

In faith, fitness, and fortitude, Tom Nikkola, CSCS

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