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:

• stress
• inflammation
• 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)
• aging

(Source)

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: 

• nausea 

• indigestion, especially after eating fatty foods or high protein foods 
• bloating 
• fatigue after a meal
• acid reflux 
• heartburn
• gas 
• diarrhea 
• iron deficiency
• brittle fingernails 
• constipation

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)

Autoimmune Diseases and Low Stomach Acid 

As mentioned, food that is not well digested in the stomach due to low stomach acid can deprive your body of nutrients, while at the same time feeding harmful bacteria in your small intestine. The wall of your small intestine is lined with a single layer of epithelial cells bound together with tight junctions that normally keep antigens and other foreign substances from passing out of the gut.

Inflammation from food sensitivities or bacterial overgrowth can loosen the tight junctions, allowing toxins and microbes to move out of the gut and into your body. This can lead to even more inflammation, which can be especially harmful if you have an autoimmune disease. In fact, leaky-gut syndrome has been proposed as a driving force for autoimmunity. (Source)

Another possible avenue connecting autoimmune conditions and decreased stomach acid production is an increase in antibodies to the parietal cells that secrete acid in the stomach. The presence of these antibodies is an indicator of autoimmune atrophic gastritis, which is more common for those with pre-existing autoimmune conditions. (Source, Source)

Low Stomach Acid and Autoimmunity Affect Each Other

Many people with autoimmune diseases also struggle with low stomach acid. Although low stomach acid is not the only cause of autoimmune symptoms, it can certainly lead to discomfort and worsen inflammation. Further, hyperimmunity triggers the release of stress hormones like cortisol, which tell the body to shift its focus to protecting itself instead of relaxing and digesting. This suppresses stomach acid production and creates a pro-inflammatory cycle. 

Autoimmune conditions that affect hormones, such type 1 diabetes and Hashimoto's thyroiditis, can also compromise stomach acid production, in which both pancreatic and thyroid hormones play a role. This is partly why people with these conditions often notice digestive symptoms. (Source, Source) 

What Can You Do About Low Stomach Acid? 

There are plenty of things you can do to address low stomach acid and keep your stomach acid levels healthy. Here are a few ways to naturally support stomach acid levels and production.

Start Your Meal With Bitter Foods

Bitter tasting foods are believed to help stimulate stomach acid secretion. These include mustard and dandelion greens, arugula, dill, citrus, fennel, ginger, and endive. One easy way to incorporate bitter foods in a meal is by making a starter salad or having a cup of ginger or fennel tea. Alternatively, before meals you can try a digestive bitter tincture, which is a concentrate of several bitter herbs. (Source, Source)

Chew Your Food

As simple as it sounds, thoroughly chewing each bite of food you take begins the digestion process and has a profound effect on digestion. Chewing signals the stomach that food is on the way, which stimulates the release of HCl and increases digestive enzyme production. (Source, Source)

Decompress Before Eating

For your digestive system to function optimally, it's best to be relaxed when you eat. Taking just 5 minutes before a meal to go outside, meditate, walk, read, or just take a break from work can help lower stress levels and prime the body for digestion. (Source)

Take a Betaine Hydrochloric Acid Supplement

Under the supervision of a health care provider, hydrochloric acid can be supplemented from a food compound called betaine HCl to boost stomach acid levels prior to meals with protein. It's best to start with a small amount (half the recommended dose) and gradually increase the dose as tolerated. (Source)

Betaine HCl is not recommended if you have an ulcer. If you are taking corticosteroid medications such as prednisone, or regularly take nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or aspirin, you should not take betaine HCl due to increased risk of gastric ulcers. In this case, digestive bitters might be a better alternative. (Source) 

Whether from a food compound or not, dietary supplements have the potential to be either helpful or harmful. It’s important to get guidance from your health care provider and stop any supplementation if you notice worsening digestive symptoms.

The Bottom Line 

Low stomach acid can be a common symptom among those in the autoimmune community. It can trigger and exacerbate leaky gut syndrome, which has been identified as a driving force of uncomfortable GI symptoms and the inflammation behind autoimmune diseases. Whether you are looking to simply clean up your digestion or significantly lower inflammation, addressing low stomach acid is an important piece of the puzzle that can help bring your system back into balance.

WellTheory’s Nutritional Therapy Practitioners are able to provide targeted supplement support once they have a complete picture of your health history. Learn more about how WellTheory can support you on your autoimmune journey through personalized supplementation and nutritional support.