Why anemia leads to decreased acidity
Iron is necessary for the functioning of enzymes involved in acid secretion. The majority of hydrochloric acid is produced by the parietal cells of the stomach. For these cells to function properly, enzymes containing iron and zinc are required. In iron deficiency anemia, the activity of enzymes (for example, H⁺/K⁺-ATPase) decreases, which reduces acid secretion.
Lack of oxygen and energy in the gastric mucosa. Anemia reduces the oxygen supply to tissues, including the gastric mucosa. Parietal cells require high energy (ATP) expenditure to produce HCl. In hypoxia, their activity decreases, which reduces acidity.
Accompanying deficiency of vitamin B12 and folate. Anemia is often associated with a deficiency of B12 (pernicious anemia). A lack of B12 is linked to atrophy of the gastric mucosa and decreased acid secretion.
Why low acidity leads to anemia
Impaired iron absorption. Iron from food is absorbed in the form of Fe³⁺, which needs to be reduced to Fe²⁺. This process occurs specifically in the acidic environment of the stomach.
With low acidity, iron remains in an inaccessible form and is poorly absorbed in the duodenum, leading to iron deficiency anemia.
Reduced absorption of vitamin B12. The absorption of B12 requires intrinsic factor, which is synthesized by parietal cells. In hypochlorhydria and atrophy of the mucosa, both acidity and the production of intrinsic factor decrease, leading to B12 deficiency anemia.
Impaired protein digestion. With low acidity, pepsinogen is poorly converted to pepsin, and proteins are incompletely broken down. This reduces the intake of amino acids necessary for the synthesis of hemoglobin and enzymes involved in erythropoiesis.
Vicious circle:
- Anemia decreases acidity → absorption of iron and B12 worsens → anemia worsens.
- Low acidity worsens the absorption of iron and B12 → anemia progresses → acidity decreases even further.
This cycle is particularly pronounced in atrophic gastritis, autoimmune damage to parietal cells, and prolonged use of proton pump inhibitors.
