Stomach acid is a concoction of hydrochloric acid, or HCl, and the enzymes pepsin and lipase that is secreted from specialized cells in the stomach when you take in food, or even when you think about food. Stomach acid plays a vital role in both digestive and immune system function.
Low stomach acid is a condition in which the stomach doesn’t make enough HCl to maintain a proper pH, leading to poor digestion and possible health problems. In this article, we will dive into what low stomach acid is and how the inflammation it causes can drive autoimmune diseases. We’ll cover the root causes, common symptoms, and strategies to address low stomach acid so you can better understand and manage your digestive health. (Source)
What Does Stomach Acid Do?
The two main jobs of stomach acid are to break food down into nutrient particles that can be absorbed and utilized by the body, and to kill any ingested pathogens. Stomach acid is produced by the parietal cells, which are found in the stomach lining. This process is mediated by several hormones, including gastrin and ghrelin (known as the “hunger hormone”), which stimulate HCl output. Hydrogen molecules in HCl stimulate the secretion of pepsin, which is another key component of stomach acid, and important for digestion. The vagus nerve is responsible for signaling many of the hormones involved in stomach acid regulation, and is often affected in autoimmune conditions. (Source, Source)
Healthy levels of stomach acid lead to a low stomach pH, meaning your stomach is very acidic. This low pH is essential for digestive enzyme function. Proteins (which are relatively large nutrient compounds) entering the stomach must be broken down by stomach acid before the enzyme pepsin can convert them into bioavailable amino acids. Bacteria and fungi that can cause infections can’t survive the acidic environment of the stomach. (This is why some probiotics are ineffective at repopulating the microbiome — they can’t survive the extremely acidic conditions of the stomach, either.) (Source, Source)
What Is Low Stomach Acid?
Low stomach acid, also known as hypochlorhydria, occurs when the stomach does not produce enough hydrochloric acid. Since stomach acid production is mediated by so many different pathways, there is no one root cause of low stomach acid. Some common risk factors include:
- Helicobacter pylori infection
- nutritional deficiencies
- a diet rich in refined carbohydrates
- excessive alcohol intake
- long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs) and proton pump inhibitors (antacids)
What Are the Symptoms of Low Stomach Acid?
Low stomach acid may present in many different ways, depending on individual factors such as age and other health conditions. Some common symptoms include:
- indigestion, especially after eating fatty foods or high protein foods
- fatigue after a meal
- acid reflux
- iron deficiency
- brittle fingernails
Because symptoms of low stomach acid such as heartburn and acid reflux are similar to those caused by excess acid, people experiencing low stomach acid often treat their symptoms by taking antacids to neutralize stomach acidity. This can worsen symptoms and exacerbate the problem. (Source)
What Does It Mean if I Have Low Stomach Acid?
The breakdown of food begins in the mouth, with chewing and the action of enzymes in saliva, and continues in the stomach. When production of stomach acid is too low, large food molecules such as proteins aren't broken down as they should be. Incomplete food breakdown signals the pyloric sphincter, which controls movement of food out of the stomach and into the small intestine, to slow down food emptying. This can cause a build up of undigested food and lead to uncomfortable symptoms. (Source)
When undigested or poorly digested food eventually empties into the small intestine, it may ferment there and serve as fuel for the harmful microbes associated with gut dysbiosis, small intestinal bacterial overgrowth (SIBO), and Candida overgrowth. These gut bugs drive inflammation and can make the intestinal lining more permeable, potentially leading to food sensitivities and leaky gut syndrome. Nutritional deficiencies from incomplete digestion may compromise metabolism, cell function, and muscle mass retention. (Source)
The Connection Between Stress and Low Stomach Acid
Chronic stress comes in many forms and has been strongly linked to low stomach acid. Epinephrine and cortisol, which are immune-modulating stress hormones, are released by the adrenal glands in a stress response that is focused on keeping you safe from perceived threats, rather than relaxing and digesting.
Part of the stress response (facilitated by your vagus nerve, connecting your stomach and brain) includes diverting energy, blood flow, and resources away from the gastrointestinal tract and into the extremities for physical activity and mental alertness. This slows down the entire digestive process, including the movement of muscles in the esophagus, stomach, small intestine, and bowel, as well as the production of stomach acid and bile. (Source, Source)