Discomfort and cramping
NOW Foods L-Glutamine Powder
Plain glutamine powder at a fraction of the capsule price, for the post-infection loose bowel that the 15 g trial studied.
- Format
- Powder, once a day
- Type
- Amino acid
- Cost
- $0.27 a day
- Customer rating
- 4.6 out of 5 from 5,772 ratings from Amazon
What customers consistently report
- Loose stools and IBS-type discomfort settling over a few weeks
- A powder that dissolves in anything and tastes of nothing
- A pound that lasts months at the trial dose
Those are the themes that recur across the reviews. High review confidence — 4.6 from 5,772 Amazon ratings on the 1 lb listing.
Why it might work
Glutamine is the main fuel of the cells lining the small intestine, and demand rises when the lining is inflamed or repairing after an infection. Supplying extra is thought to restore the tight junctions between cells, which is what the trial measured with its permeability test; a tighter lining leaks less and, in that trial, produced firmer, less frequent stools. Outside that setting the mechanism has less to act on.
What the research supports
Ingredient-level evidence from one strong trial. A randomized, placebo-controlled trial in 106 adults with post-infectious diarrhea-predominant IBS and raised gut permeability gave 15 g of glutamine a day for eight weeks: 79.6% reached the primary endpoint of a 50-point fall in symptom severity against 5.8% on placebo, daily stool frequency fell from 5.4 to 2.9, stool form normalized and permeability returned to normal. It is a single trial in a specific population, published in Gut in 2019. No trial of this NOW product was found.
What the label discloses
The only ingredient is L-glutamine, a rounded teaspoon giving about 5 g; NOW Sports products carry Informed Sport certification, an independent test for banned substances and label accuracy, which the brand states for this line. Vegan and non-GMO. One to two teaspoons a day is the label dose; the trial used three.
Who this tends to suit
We match this product to people reporting loose stools, urgency, general abdominal discomfort and bloating. It fits someone whose priority is resetting after a course of antibiotics or an upset or day-to-day comfort. Whether it is the best fit for you depends on the rest of your answers — what you have already tried, what format you will take, and anything that has to be ruled out.
Where it may not fit
The label supports vegan, gluten-free, dairy-free, no added sweeteners and minimal ingredient list. A powder only works if you will take it once a day, every day.
Side effects and what to be aware of
The trial dose was 15 g a day, three heaped teaspoons, in people with post-infectious diarrhea-predominant IBS and a leaky gut on testing; the evidence does not stretch to bloating in general. A minority report stomach pain or diarrhea. Anyone with liver or kidney disease should check first before taking that much of any amino acid.
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Others we researched for the same job
These sit in the same role as NOW Foods L-Glutamine Powder — discomfort and cramping — so they are the sensible things to weigh it against.
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Related reading
Background on how this type of product works, read from the trial evidence.