Stomach Acid

Stomach acid isn't just to help you digest your food, although thats a big part of it. It also helps break down food proteins so they cant trigger immune reactions if they make it across the gut, kill any viruses, bacteria, or parasites in your food, and plays a 100% required role in absorbing a lot of your vitamins and minerals.

The Fix:

Just so you don't have to read the entire article if you know you have low stomach acid, I'll start with how to fix it.

• The number one fix is to identify what is causing it and fix that. I have listed a bunch of possible causes below. Fixing the root cause is more of a marathon than a sprint, so you may need to use Apple Cider Vinegar or Betaine-HCL in the meantime and that's absolutely fine!

• Apple Cider Vinegar. This increases the acidity of your stomach acid. It's more of a band-aid and not an actual fix, but will help in the meantime. You'll want to take 1-2 teaspoons right before your meals.

  • You can usually buy this at any grocery store. You want one with "the mother". Braggs is a great brand. You can buy it on Amazon here.

• Betaine-HCL: This is my favorite. It increases the acid of your stomach and gives you betaine, also called trimethylglycine. Betaine can be used by the liver as a back-up to run the methylation pathway and is a relatively safe supplement. You'll want to take it as directed by the instructions on the bottle, usually right before you eat.

  • Enzymedica makes a good Betaine-HCL supplement. Amazon Link Here

Symptoms of Low Stomach Acid:

Common Digestive Symptoms

• Feeling full quickly after meals.

• Bloating and burping.

• Heartburn or acid reflux.This is the most counter-intuitive symptom. Low acid means the stomach's contents aren't being properly processed and can sit there for too long, creating pressure that pushes the valve at the top of the stomach (the LES) open, allowing acid and food to splash up into the esophagus.

• Indigestion and stomach upset. A general feeling of discomfort, heaviness, or "rock" in your stomach after eating.

• Undigested food in stool. You may notice visibly undigested food particles in your stool, as the initial breakdown of food hasn't happened properly.

• Nausea After taking supplements. Especially with vitamin pills or mineral supplements, which can irritate the stomach if not properly dissolved in acid.

Unfortunately, you can also develop nutrient deficiencies when you have chronic low stomach acid. Stomach acid is needed to absorb vitamins and minerals like folate, B12, iron, calcium, magnesium, and zinc and macronutrients like protein.

Symptoms Related to Nutrient Malabsorption

• Brittle hair, skin, and nails.

• Fatigue and low energy. This can be linked to iron-deficiency anemia (poor iron absorption) or B12 deficiency (acid is needed to separate B12 from food proteins).

• Weak bones (osteoporosis/osteopenia). This is due to low absorption of calcium, magnesium, and other bone-building minerals over time.

• Hair loss, usually because of low iron or zinc.

• Neurological symptoms like tingling in the hands and feet or "brain fog," which can be linked to B12 deficiency.

Symptoms of Long Term Low Stomach Acid

• Food sensitivities and allergies. Incompletely digested proteins can pass into the bloodstream, triggering an immune response.

• Leaky gut syndrome. The undigested food particles and potential bacterial overgrowth can damage the intestinal lining.

• Small Intestinal Bacterial Overgrowth (SIBO). Stomach acid normally kills most bacteria we ingest. With low acid, these bacteria can travel to the small intestine and colonize it.

• Chronic intestinal infections such as parasites, Candida overgrowth, or H. pylori (which can both cause and thrive in a low-acid environment).

• Weak immune system. Frequent infections due to the compromised first line of defense.

• Acne and skin rashes. Often linked in scientific studies to gut health and bacterial overgrowth.

Causes of Low Stomach Acid:

Physiological and Age-Related Causes

• Aging: Natural decline in gastric acid secretion with age. Up to 30–40% of adults over 60 have low stomach acid.

• Chronic stress. Long-term activation of the sympathetic nervous system (“fight or flight”) reduces parasympathetic (“rest and digest”) activity, decreasing stomach acid production.

• Low histamine tone. Histamine H₂ receptors on parietal cells trigger acid secretion. Low histamine (or antihistamine use) can reduce acid output.

Nutrient Deficiencies

Stomach acid production depends on several nutrients:

• Zinc deficiency. Zinc is required for carbonic anhydrase and other enzymes in parietal cells.

• Vitamin B1 (thiamine). Needed for ATP production. Low energy impairs acid secretion.

• Sodium and chloride deficiency. Acid production depends on chloride ions (HCl = hydrogen + chloride).

• Magnesium. Needed to run ATP-dependent proton pumps.

• Protein deficiency. Low protein intake reduces gastrin stimulation (the hormone that triggers acid release).

Neuroendocrine and Hormonal Causes

• Low gastrin secretion. Gastrin (from G cells in the stomach) stimulates acid production. Chronic atrophic gastritis or infection can suppress it.

• Hypothyroidism. Slows metabolism and gut motility, reducing acid secretion.

• Adrenal fatigue / low cortisol. Decreases digestive function, especially during chronic stress.

• Low vagal tone. Vagus nerve stimulation normally triggers acid release. Poor vagal tone (ex: from chronic anxiety or trauma) suppresses it.

Infectious and Autoimmune Causes

• H. pylori infection. This bacterium produces urease, which neutralizes acid locally and can damage acid-producing parietal cells over time.

• Autoimmune gastritis / pernicious anemia. Antibodies against parietal cells or intrinsic factor destroy acid-producing cells and impair B12 absorption.

• Chronic inflammation. Repeated gastritis can damage parietal cells and decrease acid output.

Medications and Chemicals

• Proton pump inhibitors (PPIs). Directly block acid production.

• H₂ blockers (ex: famotidine, ranitidine). Inhibit histamine-mediated acid release.

• Antacids / alkaline water. Neutralize existing acid and can suppress feedback loops that stimulate new acid secretion.

• NSAIDs or corticosteroids. Cause mucosal injury. Body may compensate by suppressing acid to reduce irritation.

Chronic Illnesses or Conditions

• Diabetes (autonomic neuropathy). Impairs vagus nerve and stomach motility.

• Celiac disease / gluten sensitivity. Chronic intestinal inflammation can secondarily suppress gastric function.

• SIBO (small intestinal bacterial overgrowth). Often both a cause and effect of low stomach acid.

• Chronic fatigue syndrome, fibromyalgia, or long COVID. Often involve low parasympathetic tone and poor digestive secretions.

Lifestyle and Environmental Factors

• Eating too quickly / under stress. Inhibits the cephalic phase of digestion (acid secretion starts before food enters the stomach).

• Drinking too much water during meals. Can dilute acid.

• Low-salt diet. Reduces available chloride ions for HCl.

• Excess alcohol or caffeine. Chronic overuse can damage parietal cells.

• Toxin exposure (ex: heavy metals). Damages mitochondria and glandular cells.