Sodium nitrite, pepsin nitration and stomach ulcers in rats
What it found
In rats, sodium nitrite and nitrite-rich human saliva led to a modified form of the stomach enzyme pepsin, and this was linked to fewer stomach ulcers.
The work was done in animals, not people.
What they found
Studies in people
Saliva nitrite after lettuce
In one person, nitrite in saliva rose from 95.1 micromolar after fasting to 1182.0 micromolar one hour after eating 90 grams of iceberg lettuce.
Animal and lab studies
Nitric oxide in stomach
In rats, putting sodium nitrite into the stomach raised nitric oxide gas about 200-fold. Human saliva with nitrite did the same. Urate, a substance also found in saliva, reduced this rise.
Pepsin nitration in rats
After nitrite was put into the stomach, a modified form of pepsin called nitrated pepsin was found in both the stomach lining and the stomach juice of rats. Urate prevented this change.
Stomach damage score
Rats given pentagastrin alone had stomach damage scored at 3.8 on a 0 to 6 scale. With nitrite the score fell to 2.8, and with human saliva it was 2.9. When urate was added to block pepsin nitration, the score rose to 4.6.
Myeloperoxidase in stomach
Nitrite, both as sodium nitrite and in human saliva, lowered the amount of the enzyme myeloperoxidase in the stomach lining of rats. This enzyme is a marker of inflammation.
What the authors conclude
“In sum, this work unravels a novel dietary-dependent nitrating pathway in which pepsin is nitrated and inactivated in the stomach, preventing the progression of gastric ulcers.”
Also in their conclusions
- They conclude that nitrite from the diet or from saliva triggers a process in the stomach that modifies pepsin, making it less active.
- They say this modified pepsin helps prevent the development of acute stomach ulcers in rats.
- They call for more research into how diet-dependent reactions in the gut, including effects on gut bacteria, might work.
How it was done
The authors wanted to understand whether the nitrite that reaches the stomach from saliva, after eating nitrate-rich vegetables, can change proteins in the stomach and what effect that might have.
They gave rats pentagastrin to stimulate stomach secretions, then put sodium nitrite or nitrite-rich human saliva directly into their stomachs. They measured nitric oxide gas, looked for nitrated pepsin, and scored damage to the stomach lining.
What it can’t tell you
- These experiments were done in rats. They cannot show whether the same changes in pepsin and stomach ulcers would happen in people.
- The study used a single sample of human saliva and one person's saliva for the nitrite measurement, so it does not show how much these levels vary between people.
Who paid
- Authors work at
- University of Coimbra, Portugal; Karolinska Institute, Sweden; Center for Free Radical and Biomedical Research, Uruguay
The paper
- Title
- Role of nitrite, urate and pepsin in the gastroprotective effects of saliva
- Type
- Study
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Rocha BS, Lundberg JO, Radi R, Laranjinha J (2016). Role of nitrite, urate and pepsin in the gastroprotective effects of saliva. Redox biology. doi:10.1016/j.redox.2016.04.002Free full textPubMed 27156250DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error