L-Glutamine
The most abundant amino acid in your body — and the primary fuel source for your gut lining and immune cells. Here's when supplementing makes sense and how much to take.
L-glutamine is the amino acid your gut lining and immune cells run on. When you're stressed, training hard, or dealing with gut issues, your body uses more glutamine than it can make. Supplementing helps repair and maintain your intestinal barrier (reducing "leaky gut"), supports immune function, and aids muscle recovery.
Good for you if: You have gut issues (bloating, food sensitivities, IBS), train intensely, get sick frequently, or are recovering from illness or surgery.
Dive deeper into the researchCommon side effects
- Generally very well tolerated
- Bloating or gas possible when starting high doses
- Avoid if you have liver cirrhosis or kidney disease
What does L-glutamine do?
Your gut lining replaces itself every 3–5 days. That rapid cell turnover requires enormous amounts of fuel — and the fuel your gut cells prefer is glutamine. When glutamine is depleted (from stress, intense exercise, poor diet, or illness), your gut barrier weakens. Small gaps form between cells, allowing food particles and bacteria to cross into your bloodstream. This is what's commonly called "leaky gut."
Supplementing with L-glutamine gives your gut the building blocks it needs to repair and maintain a tight barrier. It's also the primary fuel for your immune cells (lymphocytes and macrophages), which is why immunity drops when glutamine is depleted.
What can you expect?
- Less bloating and gut discomfort — as your intestinal barrier repairs
- Fewer food sensitivities — a tighter gut barrier means less immune activation
- Faster muscle recovery — reduced soreness after intense training
- Stronger immunity — fewer colds and infections, especially during heavy training
- Reduced sugar cravings — glutamine provides an alternative fuel for the brain
How to take it
5 g twice daily (10 g total), mixed in water. Take on an empty stomach — morning and before bed work well. For intensive gut repair, some practitioners use 15–20 g/day for 4–8 weeks, then reduce to maintenance.
Powder is the most cost-effective form. Dissolves easily in water with almost no taste.
How long to take it: Gut barrier improvements begin within 2–4 weeks. For ongoing gut support, many people take 5 g/day as maintenance. For exercise recovery, take it around training.
Which form to buy?
| Form | Dose | Notes |
|---|---|---|
| L-Glutamine powder | 5–15 g/day | Best value; unflavoured, dissolves easily |
| Capsules | 500–1000 mg each | Convenient but expensive per gram |
| Gut-repair blends | Varies | Often combined with zinc carnosine and DGL |
Widely available in India from MuscleBlaze, NOW Foods, and Optimum Nutrition. Powder is very affordable: ₹500–800 for 250 g (about a month's supply at 10 g/day).
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Get early accessFrequently Asked Questions
Does L-glutamine actually fix leaky gut?
Yes, there's good evidence. Glutamine is the primary fuel for enterocytes (gut lining cells). Clinical studies in critically ill patients and athletes show it helps maintain intestinal barrier integrity. Supplementing tightens the junctions between gut cells, reducing permeability.
Can L-glutamine help with sugar cravings?
Many people report this. Glutamine can serve as an alternative fuel for the brain when blood sugar dips, potentially reducing the craving signal. Take 500 mg under the tongue when a craving hits. The clinical evidence is anecdotal but the mechanism makes physiological sense.
Is L-glutamine good for athletes?
Yes. Intense training depletes glutamine stores, which can impair immunity and slow recovery. Studies show supplementation reduces post-exercise infections and muscle soreness. Take 5–10 g around training sessions.
Can I take L-glutamine long-term?
Yes. Glutamine is a naturally occurring amino acid present in most protein-rich foods. Supplementing at 5–15 g/day is well-tolerated long-term. Those with liver or kidney disease should avoid it or consult their doctor.
How it works in your body
Glutamine serves as the primary metabolic fuel for enterocytes (intestinal lining cells) and immune cells. In your gut, it maintains the tight junctions between cells that form the intestinal barrier. When glutamine is depleted — from stress, illness, or intense exercise — these junctions weaken, increasing intestinal permeability ("leaky gut").
For immunity, glutamine fuels the rapid proliferation of lymphocytes and provides substrate for macrophage function. Plasma glutamine drops significantly during critical illness and heavy training, correlating with increased infection rates. Supplementation helps maintain immune competence during these high-demand periods.
What the studies show
- Gut barrier: Maintains intestinal tight junction integrity in ICU patients and athletes
- IBS: Reduced intestinal permeability and symptoms in diarrhoea-predominant IBS
- Exercise immunity: Reduced post-marathon upper respiratory infections
- Muscle recovery: Reduced delayed-onset muscle soreness in resistance training
- Hospital outcomes: Reduced infections and length of stay in surgical patients
Side effects & safety
- Very well tolerated — Side effects are rare at recommended doses (5–15 g/day).
- Bloating — Possible when starting high doses. Ramp up gradually.
- Liver disease — Avoid in liver cirrhosis. Glutamine is metabolised to ammonia, which the liver must clear.
- Kidney disease — High-dose glutamine may stress kidneys. Consult your doctor.
- Cancer — Theoretical concern that glutamine may fuel tumour growth. Discuss with your oncologist if relevant.
Which labs to check
- hsCRP — tracks systemic inflammation (often elevated with leaky gut)
- Liver enzymes (ALT, AST) — baseline check, especially at higher doses
- Albumin — overall nutritional and gut health status
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