Low stomach acid – or hypochlorhydria – is rampant and the cause of so many gut and health problems, including heartburn, reflux, SIBO, mineral deficiencies, and hypothyroidism. Learn 10 root causes + how to know if you have it!
Note from Dena: This post was co-written with Deina Hamdan, Dietetic Intern, as part of a research partnership between Back To The Book Nutrition and post-graduate nutrition students from the University of Houston.
We hear a lot about excess stomach acid and how to lower it, but many people with heartburn, reflux, bloating, and IBS actually have low stomach acid. Read on to learn what causes low stomach acid and how to know if you have it!
WHAT IS LOW STOMACH ACID?
Low stomach acid, or hypochlorhydria, occurs when your body has low levels of hydrochloric acid (HCl), making it harder to break down food and nutrients. When this happens, the body also releases less digestive enzymes and bile to help break down food, causing a variety of digestive symptoms (8).
SYMPTOMS OF LOW HCL
Here are a few symptoms that you may experience along with hypochlorhydria:
- Heartburn, acid reflux, and GERD
- Poor digestion after eating heavy foods – you may feel a heavy sensation in your stomach, especially after eating high protein foods
- Low immune function
- Food sensitivities
WHY LOW STOMACH ACID IS BAD FOR YOU
Although a lower HCl level itself is enough to cause symptoms, leaving it untreated may also lead to several other health complications such as:
- Heartburn, Reflux, and GERD – Adequate stomach acid helps keep the lower esophageal sphincter (LES) closed. The LES is like a door between the throat and the stomach. When stomach acid is low, the LES can open, causing stomach contents to reflux back up into the esophagus and cause symptoms of heartburn, reflux, and GERD. Low stomach acid also means food stays in the stomach longer, making heartburn, reflux, and GERD more likely to occur.
- H. pylori – Helicobacter pylori is bacteria that infects the lining of the stomach that thrives at a more neutral pH. Low stomach acid levels allow the usually acidic stomach to become more neutral, which can allow H. pylori to overgrow.
- SIBO (Small Intestinal Bacterial Overgrowth) – Low gastric pH also lowers pH of the small intestines, and bacteria are more likely to overgrow at these higher pH levels. Poorly digested foods also move more slowly through the GI tract, giving bacteria more food to “eat” and more time to do it, promoting them to multiply.
- Candida & Other Yeast Overgrowths – Low stomach acid promotes small intestinal yeast overgrowth (SIFO) very similarly to how it contributes to SIBO. When poorly digested food moves through the GI tract more slowly and at a higher pH level, it creates a “buffet” for yeasts to feast on. Remember, Candida and other yeasts usually aren’t a problem at normal levels, but excessive growth can cause symptoms and additional health complications.
- Parasites – HCl kills incoming parasites. When this “first line of defense” is down, they are more likely to take up residence in our gut.
- IBS (Irritable Bowel Syndrome) – When poorly digested food moves more slowly through the GI tract because of hypochlorhydria, pain, bloating, constipation, and other IBS symptoms can occur. Having SIBO or SIFO usually makes IBS symptoms even worse.
- Nutrient Deficiencies – Deficiencies in iron, zinc, folate, B12, calcium, magnesium, potassium, copper, protein, and other nutrients may occur when stomach acid is low because the intestines are unable to absorb nutrients from poorly digested foods leaving the stomach.
- Lower Digestive Enzyme Production – HCl and normal gastric pH play a significant role in the production of the digestive enzymes that help further break down food in the intestines.
- Lower Bile Secretion – When HCl is low, less bile is released, decreasing absorption of fat and fat-soluble nutrients like vitamins A, D, E, and K2, as well as omega-3 fatty acids. Bile is also antibacterial, so lower output due to low stomach acid can give rise to pathogens and overgrowths in the gut.
- Leaky Gut Syndrome – Low stomach acid can lead to overgrowths of bacteria and yeast that damage the gut lining, causing it to become more permeable or “leaky.”
- Food Sensitivities – Poorly digested food particles due to low HCl are more likely to trigger immune reactions, especially when they pass through a leaky gut wall and into circulation. This is because when proteins are not properly broken down, they become irritants and stimulate an immune response.
- Osteoporosis – Since a decrease in stomach acid leads to reduced absorption of nutrients necessary for bone health (calcium, magnesium, protein, phosphorus, etc.), osteopenia or osteoporosis may develop as a result.
- Hair loss and Breakage – Iron, zinc, and B vitamins are all needed for healthy hair. Adequate HCl is necessary to absorb these nutrients and prevent hair loss and breakage.
- Depression and Anxiety – Low stomach acid is an overlooked cause of depression and anxiety since it reduces the absorption of iron, zinc, magnesium, and copper, which have all been linked to increased depression and anxiety.
- Low Thyroid function – Low stomach acid reduces the absorption of nutrients like iron, zinc, magnesium, selenium, and B12 needed to make thyroid hormone and convert it into its active form. Interestingly, it seems that low thyroid can also contribute to low stomach acid, making it a vicious cycle if you do not address it appropriately (3,7).
- Low immune function – Low immune function may make you more prone to infections. Hypochlorhydria reduces the absorption of these nutrients needed for optimal immune function, such as protein, iron, zinc, selenium, and vitamins A and D.
What Causes Low Stomach Acid?
Here are some of the most common causes of reduced stomach acid that may help you understand and address your symptoms:
1. Prescription and Over the Counter Medications
Prescription and over the counter medications for acid reflux, heartburn, and allergies can provide short-term symptom relief. But, in most cases, they don’t address the root cause and can lower stomach acid, sometimes worsening the root cause and leading to downstream gut dysfunction like overgrowths of bacteria, yeast, or parasites, SIBO, Leaky Gut, and more (9).
Medications that lower stomach acid include:
- PPI’s (Proton Pump Inhibitors) – Prilosec, Nexium, Prevacid, etc.
- Antihistamines (H2 Blockers) – Zantac, Pepcid, Tagamet, etc.
- Antacids – Tums, Alka-Seltzer, Pepto-Bismol, Gaviscon, etc.
2. H. pylori
Helicobacter pylori is an extremely common bacteria and is the most common cause of gastritis (inflammation of the stomach lining). When H.pylori damages the stomach lining, it can reduce stomach acid and, in some cases, lead to other more serious complications like ulcers or cancer (10).
3. Pernicious Anemia
Pernicious anemia is an autoimmune condition where the body makes antibodies that attack the parietal cells in the lining of the stomach, causing gastritis, low B12 absorption, and low stomach acid production. Pernicious anemia is rare in the general population, but becomes much more common as we age, becoming almost 5 times more likely once we hit 80 years old. Pernicious anemia is also more common among those with European or African ancestry (12, 15).
Many studies show that chronic stress reduces stomach acid, but preliminary research suggests acute stress (i.e., stressful events around the time of eating) may affect different people differently.
More study is needed to confirm, but authors of one small study showed that personality traits may determine whether stomach acid goes up or down in response to acute stress. They found that stressful situations significantly increased stomach acid levels in “high strung” individuals who were more prone to impulsivity, but decreased it in those who had a more laid back temperament (1).
5. Low Zinc
Zinc is needed to make stomach acid. Some of the most common causes of zinc deficiency include:
- Vegetarian and vegan diets
- Crohn’s Disease
- Ulcerative Colitis
- Diuretic medications
- Birth control pills
- Iron supplementation
- Young children who often dislike meat
6. Low Sodium or Potassium
Sodium and potassium are both used to make stomach acid (15). Surprisingly, many people don’t get enough of these two electrolytes due to increased needs from chronic stress (sodium depletion in earlier stages, and potassium depletion later on), choosing to restrict salt intake (which is our primary source of sodium), taking certain medications that deplete one or both of them, and low intake of fruits and veggies that supply potassium.
7. Low Thyroid Function
Studies have shown that those hypothyroid patients have lower levels of gastrin (which triggers stomach acid secretion), have higher rates of B12 deficiency (B12 requires stomach acid for absorption), and their stomachs take twice as long to empty after eating, all of which point to low stomach acid (4, 10, 13, 14). Interestingly, optimal stomach acid is needed to absorb key nutrients like iron, zinc, iodine, and selenium that help the body make thyroid hormone. So low stomach acid can cause hypothyroidism, and vice versa, creating a vicious cycle.
HCl levels naturally decrease as we age and are approximately 30% lower in adults 65 years and older (5).
9. Gastric Bypass Surgery
When a portion of the stomach is stapled off or removed surgically, the number of parietal cells that release HCl decrease, resulting in lower stomach acid (15).
10. Stomach Cancer
Depending on which area of the stomach is affected by the cancer, stomach acid could be compromised. Surgery or radiation to the stomach area as cancer treatment can also decrease HCl output (15).
How to Test for Low Stomach Acid
Here are some ways you can test yourself to determine whether your symptoms are related to low stomach acid:
1. Baking Soda “Burp Test”
This free and easy test can be done at home and is a helpful indicator of HCl levels:
- First thing in the morning (before eating or drinking), mix 1/4 teaspoon of baking soda in 4 oz of water.
- Drink the mixture.
- Set a timer to see how long it takes you to burp.
- Burp within 2-3 minutes, you likely make enough stomach acid and do not need Betaine HCl supplementation.
- Burp between 3-5 minutes, you may have inadequate stomach acid and could benefit from Betaine HCl supplementation.
- Don’t burp until after 5 minutes, or not at all, you very likely have inadequate stomach acid and would likely benefit from Betaine HCl supplementation.
Since acid reflux medications may affect the results of this test, it is best to try it 2-3 days after the last time you took such medications (do not stop taking prescription medication without speaking to your provider first).
2. The Betaine Challenge Test
This at-home test is commonly recommended by holistic and functional medicine providers, but it’s not always reliable and can be risky since not everyone will experience burning or discomfort and it can cause damage to the stomach without the person realizing it.
The Betaine Challenge Test is done by consuming a betaine HCl supplement at mealtimes and increasing the dose until a burning or noticeable discomfort develops. Do not attempt without consulting your provider to avoid damage to your stomach.
3. The Heidelberg Test
This test can be performed in your doctor’s office, but it is expensive and not usually covered by insurance. It involves swallowing a small device that measures gastric acid before and after consuming a baking soda solution. It’s accurate, but usually not done due to high cost.
About the Co-Author:
Deina Hamdan is a dietetic intern that is currently pursuing an MS in Nutrition at the University of Houston. As an Arab who was raised in New York, her dietary habits were equally influenced by two very different cultures. Her passion for nutrition grew when she realized that several factors could influence a person’s perspective on healthy eating.
Disclaimer: Information on this site is intended only for informational purposes and is not a substitute for medical advice. Always consult with a trusted healthcare provider before implementing significant dietary change. Read additional disclaimer info here.