How to fix your gut - stomach acid maxxing (part 1)

Stomach acid maxxing

OVERVIEW: What Is Stomach Acid and why we need it?

Stomach acid is primarily hydrochloric acid (HCl), secreted by parietal cells in the gastric glands of the stomach lining.
Its main functions:

• Activate pepsinogen → pepsin (protein digestion)

• Denature proteins (for absorption)

• Kill pathogens

• Facilitate mineral absorption (e.g., iron, calcium, magnesium)

  • Low stomach acid can lead to deficiencies such as zinc, folate, magnesium, etc, which can lead to low testosterone, ED, brain fog, low grade inflammation, low dopamine, stress intolerance, etc.

• Immune defence

Poor stomach acid can lead to undigested food reaching the colon. Bacteria will then ferment on those food particles (lipids, starches, amino acids, etc.) and create toxins, which will then inflame the intestine and cause leaky gut. Then the toxins will enter into the body and cause low-grade inflammation in every organ.

THE PHASES OF STOMACH ACID SECRETION

There are three main phases of gastric acid secretion, coordinated by the nervous and hormonal systems:

1. Cephalic Phase (30% of acid secretion)

• Triggered before food enters the stomach—from thought, smell, sight, taste, or chewing.

• Mediated by the vagus nerve (cranial nerve X).

• Vagus releases acetylcholine (ACh), which stimulates:

  • Parietal cells directly to release HCl.

  • Enterochromaffin-like (ECL) cells to release histamine.

  • G cells to release gastrin.

• These signals prime the stomach for digestion.

2. Gastric Phase (60% of acid secretion)

• Begins once food enters the stomach.

• Stimuli: stomach distension, presence of proteins, amino acids, and pH rise.

• Stretch and chemical signals stimulate:

  • Gastrin release (from G cells in the antrum)

  • Histamine release (from ECL cells)

  • ACh via local and vagal reflexes

• Gastrin and histamine potentiate parietal cells to secrete more HCl.

3. Intestinal Phase (10%)

• Occurs when chyme enters the duodenum.

• Initially causes a small stimulatory effect via intestinal gastrin.

• Soon after, inhibitory feedback dominates to avoid over-acidification of the small intestine.

THE PARIETAL CELL: Mechanism of HCl Secretion

Parietal cells use a proton pump (H⁺/K⁺ ATPase) to secrete H⁺ ions into the stomach lumen:

1. CO₂ + H₂O → (via carbonic anhydrase) → H₂CO₃ (carbonic acid)

2. H₂CO₃ dissociates → H⁺ + HCO₃⁻

3. H⁺ is pumped out into the gastric lumen via H⁺/K⁺ ATPase.

4. Cl⁻ enters the cell via a basolateral chloride-bicarbonate exchanger and exits into the lumen to combine with H⁺ → HCl.

STIMULATORS OF ACID SECRETION

Neural:

• Acetylcholine (ACh) – from the vagus nerve

  • Directly stimulates parietal cells

  • Indirectly promotes histamine and gastrin release

Hormonal:

• Gastrin – secreted by G cells

  • Stimulates parietal and ECL cells

• Histamine – released by ECL cells

  • Binds H2 receptors on parietal cells to increase HCl

• Ghrelin – hunger hormone that can indirectly increase acid

Local:

• Stomach stretch (mechanoreceptors)

• Protein presence (especially aromatic amino acids)

INHIBITORS OF ACID SECRETION

Hormonal:

• Somatostatin – secreted by D cells when pH drops too low

  • Inhibits G cells (gastrin), ECL cells (histamine), and parietal cells directly

• Secretin – from the duodenum, in response to acidic chyme

  • Stimulates bicarbonate release from pancreas

  • Inhibits gastric acid

• Cholecystokinin (CCK) – also inhibits gastric emptying and acid

Neural:

• Enterogastric reflex – triggered by duodenal distension, low pH, or high osmolarity

  • Reduces vagal output

Others:

• Low gastric pH (<3) – directly suppresses further gastrin release

How to maximize stomach acid secretion…

…to maximize nutrient absorption and prevent dysbiosis.

I discuss:

• How to increase stomach acid

• How to eat meals to support proper stomach acid secretion

• Which supplements to use (basic and advanced stack)

• What inhibits stomach acid secretion

• What to do about GERD

The mistake people often make is to add digestive enzymes, but they skip stomach acid optimization. Stomach acid breaks down food into smaller particles so that digestive enzymes can do their work. But when there isn’t enough stomach acid, food particles aren’t properly broken down, thus digestive enzymes aren’t very useful.

Let’s start with how to increase stomach acid: