Gut Health Series: Stomach Acid

Stomach acid, or gastric acid, is a watery, colorless fluid that’s produced by your stomach’s lining.

It’s highly acidic and helps break down food for easier digestion. This helps your body absorb nutrients more easily as food moves through your digestive tract.

In order to break down everything from meat to tough, fibrous plants, stomach acid has to be highly acidic.

Your body is designed to handle average levels of stomach acid so that it doesn’t cause you any illness or health complications.1

With a pH between 1 and 3, gastric acid plays a key role in digestion of proteins by activating digestive enzymes, which together break down the long chains of amino acids of proteins. Gastric acid is regulated in feedback systems to increase production when needed, such as after a meal. Other cells in the stomach produce bicarbonate, a base, to buffer the fluid, ensuring a regulated pH. These cells also produce mucus – a viscous barrier to prevent gastric acid from damaging the stomach. The pancreas further produces large amounts of bicarbonate and secretes bicarbonate through the pancreatic duct to the duodenum to neutralize gastric acid passing into the digestive tract. 2

The primary active component of gastric acid is hydrochloric acid (HCl), which is produced by parietal cells in the gastric glands in the stomach. 2

Why stomach acid is so important to your health?3

The stomach is intended to be highly acidic for several very important reasons:

  1. The acidity neutralises harmful pathogens like yeast and bacteria that enter the body in food. If these are not destroyed, they may potentially cause food poisoning or upset the delicate balance of gut bacteria; and this in itself can have a whole host of further digestive ramifications such as diarrhoea, gas, bloating and pain.
  • The acidity activates the protein-digesting enzyme (pepsin) in the stomach which is required alongside hydrochloric acid to commence the splitting apart of protein molecules. The acid unravels proteins to enable the pepsin enzyme to get to work. Food is churned and mixed with the acid turning it into a type of gruel called “chyme” before moving onto the next stage of digestion in the small intestines.

*If you can see undigested food in your stools (other than foods like sweetcorn), it can be a good indicator that digestive efficiency in your stomach is less than adequate as food should be unrecognizable once it leaves the stomach.

  • The acidic chyme triggers the release of further digestive secretions in the small intestines required for the complete breakdown of food for its absorption into the bloodstream.
  • The acid helps liberate vitamin B12 from food and helps activate intrinsic factor required to enable B12 to be absorbed. Symptoms of B12 deficiency include memory loss, disorientation, hallucinations, and tingling in the arms and legs.
  • The acid has an important role in the ionization of minerals like iron, zinc, calcium and magnesium for their effective absorption into the bloodstream. Long-term, less than adequate levels of minerals can have far-reaching effects on bone health, red blood cell production, energy, to name but a few.
  • The acid helps to close the lower oesophageal sphincter which helps reduce the ability of the acid to pass back into the oesophagus which may lead to acid reflux.
  • The acid helps to activate the pyloric sphincter to enable ‘chyme’ to pass into the small intestines and therefore not remain in the stomach longer than necessary.

Causes of high stomach acid

Some of the most common causes include:

  • Rebound acid hypersecretion: H2 blockers are a type of medication that can decrease stomach acid. Sometimes, people coming off of this medication can have an increase in stomach acid. There’s evidence that this can also happen after coming off of proton pump inhibitors (PPIs), although this is controversial.
  • Zollinger-Ellison syndrome: With this rare condition, tumors called gastrinoma form in your pancreas and small intestine. Gastrinomas produce high levels of gastrin, which causes increased stomach acid.
  • Helicobacter pylori infection: H. pylori is a type of bacteria that can colonize the stomach and cause ulcers. Some people with an H. pylori infection may also have high stomach acid.
  • Gastric outlet obstruction: When the path leading from the stomach to the small intestine is blocked, it can result in increased stomach acid.
  • Chronic kidney failure: In some rare cases, people with kidney failure or those undergoing dialysis may produce high levels of gastrin, leading to increased production of stomach acid.4

Causes of low stomach acid (Hypochlorhydria)

Some of the most common causes for low stomach acid include:

  • Age. Hypochlorhydria is much more common as you get older. People over the age of 65 years are most likely to have low levels of hydrochloric acid.
  • Stress. Chronic stress may decrease production of stomach acid.
  • Vitamin deficiency. Deficiency of zinc or B vitamins may also lead to low stomach acid. These deficiencies may be caused by inadequate dietary intake or by nutrient loss from stress, smoking, or alcohol consumption.
  • Medications. Taking antacids or medications prescribed to treat ulcers and acid reflux, such as PPIs, for a long period of time may also lead to hypochlorhydria. If you take these medications and are concerned that you have symptoms of low stomach acid, speak with your doctor before making changes to your medications.
  • H. Pylori. Infection with H. Pylori is a common cause of gastric ulcers. If left untreated, it can result in decreased stomach acid.
  • Surgery. Surgeries of the stomach, such as gastric bypass surgery, can reduce production of stomach acid.5

Symptoms of high stomach acid4

Some signs that you may have high stomach acid include:

Symptoms of low stomach acid6

Immediate symptoms involve indigestion, including:

  • Abdominal pain.
  • Bloating.
  • Gas.
  • Diarrhea.
  • Constipation.
  • Undigested food in poop.
  • Reflux.
  • Heartburn.

Prolonged hypochlorhydria may produce symptoms of nutritional deficiencies, including:

  • Brittle fingernails.
  • Hair loss.
  • Paleness.
  • Fatigue.
  • Weakness.
  • Numbness or tingling in hands and feet.
  • Memory loss.
  • Headaches.

What’s a good diet for low stomach acid?6

Diet alone won’t restore your stomach acid, but these guidelines may help improve your digestion while living with hypochlorhydria:

  • Eat protein first. Protein at the beginning of your meal helps to stimulate acid production.
  • Drink fluids later. Save drinks until at least 30 minutes after you’ve finished your meal. This gives your stomach more time to produce acid and metabolize proteins.
  • Eat probiotic foods, including yogurt, miso and sauerkraut, to help boost your good gut bacteria and keep harmful bacteria in check.
  • Avoid overly fatty and processed foods, which are harder to digest and offer little nutrition.
  • Fortify your vegetarian diet. Many of the deficiencies associated with low stomach acid, including protein, iron, calcium and vitamin B12, are most abundant in animal-sourced foods, such as meat, fish and dairy products. If you’re a vegetarian, make sure you’re supplementing these nutrients. This might be easiest with a quality health shake blend.
  • Eat smaller meals and chew thoroughly to give your digestive system its best chance to break the food down.
  • Finish your last meal two to three hours before bedtime. Give your body time to digest before lying down.

Read part 2 of our Gut Health Series


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Nada Eltom

Nada Eltom (Hungary), CNP, CFMP worked as a physician (laboratory medicine specialist) in Hungary before immigrating to Canada where she earned her Certified Nutritional Practitioner, and a Certified Functional Medicine Practitioner, designations. She completed her Bachelor of Medicine and Surgery in Semmelweis University, Hungary, her Holistic Nutrition Diploma from the Institute of Holistic Nutrition, Canada and her Functional Medicine Certificate from the Functional Medicine University, USA.