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Gastric acid level of humans must decrease in the future.
1Department of Gastroenterology, Chiba Hokusoh Hospital, Nippon Medical Scool, Inzai 270-1694, Chiba, Japan. s-fujimori@nms.ac.jp.
World Journal of Gastroenterology
|December 3, 2020
Summary
Human gastric acid levels are high, likely due to ancient scavenging diets requiring bacterial disinfection. Modern hygiene may allow for a gradual decrease in stomach acid over time.
Area of Science:
- Human physiology
- Evolutionary biology
- Gastroenterology
Background:
- Proton pump inhibitors reduce gastric acid but do not typically impede digestion.
- The small intestine possesses enzymes for digestion and absorption, independent of stomach acid.
- Human stomach acid pH is lower than most animals, similar to scavengers.
Purpose of the Study:
- To explore the evolutionary reasons for high human gastric acid production.
- To investigate the link between ancient human diets and current physiological traits.
- To hypothesize about the future of human gastric acid levels in modern environments.
Main Methods:
- Comparative analysis of human and animal gastric acid pH.
- Review of evolutionary hypotheses regarding early human diets and locomotion.
- Correlation of environmental hygiene with physiological adaptations.
Main Results:
- High gastric acid concentration in humans may have evolved for disinfecting carrion, a likely food source for early bipedal humans.
- This adaptation allowed for the consumption of bacteria-laden food, crucial for survival.
- Modern hygienic conditions reduce the need for such high levels of gastric acid.
Conclusions:
- Human gastric acid levels are a product of evolutionary adaptation to ancient dietary practices.
- Improved sanitation has diminished the selective pressure for high gastric acid production.
- A long-term trend towards decreased gastric acid levels in humans is plausible given current environmental conditions.
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