Human stomach acid, with a pH of roughly 1.5 to 3.5, activates the enzyme pepsin and kills many ingested pathogens.

the verdict

SUPPORTED

the evidence backs this

Recorded sources

7 sources for · 0 against

Counts group repeated records of the same source within each side. They do not measure evidence strength or source independence.

Is it true that human stomach acid, with a pH of roughly 1.5 to 3.5, activates the enzyme pepsin and kills many ingested pathogens?

Yes. A reference source states human gastric acid pH is between one and three, protects against ingested pathogens, and activates pepsinogen to pepsin, covering the claim. Other sources partially support acid's role in activating pepsin and inhibiting pathogens, though some use animal models or lack the pH range.

Verdict: SUPPORTED · 7 sources for, 0 against · Last checked 2 Oct 2026

The private library was unavailable for some searches in this check. Missing library results are not evidence against the claim.

Evidence for · 7

The Evolution of Stomach Acidity and Its Relevance to the Human Microbiome

2015

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Beasley, D. E., Koltz, A. M., Lambert, J. E., Fierer, N., & Dunn, R. R. (2015). The Evolution of Stomach Acidity and Its Relevance to the Human Microbiome. doi.org. https://doi.org/10.1371/journal.pone.0134116

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More for · 6

Influence of Gastric Acid on Susceptibility to Infection with Ingested Bacterial Pathogens -

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Influence of Gastric Acid on Susceptibility to Infection with Ingested Bacterial Pathogens - PMC Lock. (n.d.). pmc.ncbi.nlm.nih.gov. https://doi.org/10.1128/IAI.01138-07

Characteristics of Crude Pepsin Enzyme from Catfish Stomach (Clarias sp.)

2025

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Fatiranes, E., Sidauruk, S., & Hasan, B. (2025). Characteristics of Crude Pepsin Enzyme from Catfish Stomach (Clarias sp.). doi.org. https://doi.org/10.58920/aqlis0202418

Human Digestive System/Stomach

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Human Digestive System/Stomach. (n.d.). en.wikibooks.org. https://en.wikibooks.org/wiki/Human_Digestive_System/Stomach

Dysbiotic infection in the stomach.

2015

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Iizasa, H., Ishihara, S., Richardo, T., Kanehiro, Y., & Yoshiyama, H. (2015). Dysbiotic infection in the stomach.. doi.org. https://doi.org/10.3748/wjg.v21.i40.11450

Gastric acid

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Gastric acid. (n.d.). en.wikipedia.org. https://en.wikipedia.org/wiki/Gastric_acid

The Structure of Dairy Products at Different Length Scales Drives the Mechanism of Digestion and the Nutrient Bioavailability

2025

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The Structure of Dairy Products at Different Length Scales Drives the Mechanism of Digestion and the Nutrient Bioavailability. (2025). hal.inrae.fr. https://hal.inrae.fr/hal-05463762v1

also asked as

Does human stomach acid have a pH between 1.5 and 3.5 to activate pepsin and kill pathogens?
Is it true that stomach acid with a pH of 1.5 to 3.5 activates pepsin and destroys ingested germs?
Does stomach acid function with a pH around 1.5 to 3.5 to kill pathogens and activate pepsin?
Is it a fact that human stomach acid activates pepsin and kills pathogens at a pH of 1.5 to 3.5?

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