There is lots of talk, especially on social media, about the importance of the gut microbiome to our intestinal health. The role the stomach plays in our overall health is often overlooked and it's time to change that. Our stomach is teeming with digestive enzymes and juices that are critical to our ability to break down and use the nutrients in our food and minimize the proliferation of bad bacteria in our digestive system.
What is stomach acid and what does it do?
Stomach acid, also known as gastric acid, is exactly what its name implies - it's a highly acidic secretion (made up of hydrochloric acid, potassium chloride, and sodium chloride) produced by the lining of the stomach.
After food is partially digested in the mouth, it travels down the esophagus and reaches the stomach where a myriad of digestive enzymes and juices are released. Part of this juice is, you guessed it, stomach acid. Muscle contractions will help mix the food you just chewed and swallowed with these digestive juices to further break down the food components to a form that can be used by the body.
Without stomach acid, we wouldn't be able to digest protein! Why? Well, stomach acid activates pepsin, a protein-digesting enzyme also made in the stomach. If your meal is especially rich in protein, more stomach acid will be secreted to support its breakdown. Once the stomach does its job, its acid contents (formerly known as chyme) pass to the small intestine where digestion and absorption continue.
Why is it important?
So, we know that stomach acid is essential to the proper breakdown of food in the stomach. But, it also helps prime the small intestine for digestion and absorption. The acidic pH of chyme (aka the semi-fluid mass of partially digested food formed in the stomach) stimulates the small intestine and pancreas to release additional secretions to continue the digestion and absorption process.
Stomach acid also has disinfecting properties (cool, right?). The stomach plays such an important role in defending us from harmful pathogens, or disease-causing microorganisms like bacteria and yeast, that might have contaminated the food we ate. If it weren't for stomach acid, we would likely be getting sick much more often and our gut microbiome would be out of whack (more on this later...).
As if it didn't do enough...it does more. Stomach acid helps free vitamin B12 (found in animal foods) from food components (specifically protein) and activates the protein intrinsic acid, which is essential for the absorption of B12 in the body.
Last but not least, it helps shut the lower esophageal sphincter which is essentially a gate between the esophagus and stomach. It opens when food passes from the esophagus to the stomach and then closes to prevent the chewed food from traveling back into esophagus (i.e. acid reflux).
Stomach acid is pretty amazing, isn't it? When everything is working as it should, we're taken care of. But, producing too much stomach acid or not enough stomach acid are both problematic.
What happens if you make too much?
Your body can experience a rise in its production of stomach acid if you have H. pylori, a bacterial infection, if there's an increase in the hormones that stimulate stomach acid production, or if you have a rare digestive disorder known as Zollinger-Ellison syndrome. High stomach acid can put you at a greater risk for developing peptic ulcers, which are sores found in the stomach and small intestine.
Signs of too much stomach acid include abdominal discomfort, nausea, vomiting, bloating, diarrhea, unintended weight loss, and decreased appetite.
Depending on the root cause, overproduction of stomach acid is typically treated with proton-pump inhibitors (PPIs)*, antibiotics (if you have a bacterial infection like H. pylori), surgery, and/or lifestyle modification.
*A note on proton-pump inhibitors...PPIs are one of the most prescribed drugs in the world! While they have been deemed safe, more recent research on their long-term use has shown that PPI medications may increase the risk for fracture, chronic kidney disease, infection, micronutrient deficiencies, and dementia. However, this research is still in its infancy and more studies need to be performed to investigate the long-term consequences of PPI use.
What happens if you make too little?
Low stomach acid is actually much more common than you think. If you have low stomach acid, also called hypochlorhydria, you aren't producing enough stomach acid and the acid that is produced is at a pH greater than it should be.
As we age, we release less stomach acid. Other causes of low stomach acid include lack of micronutrients like vitamin B12, zinc, and magnesium which are needed to make stomach acid, long-term use of antacids and PPIs, gastric surgery, infection, undereating, and stress.
If the stomach environment isn't acidic enough, it can lead to an imbalance in the gut microbiome, contribute to the development of small intestinal bacterial overgrowth (SIBO), and may result in indigestion, iron deficiency anemia, protein deficiency, and micronutrient deficiencies (vitamin B12, calcium, and magnesium).
Here are a few ways to support stomach acidity:
Slow down during mealtime and chew your food well.
Be present while you're eating - limit distractions and really taste your food. Make it a sensory experience.
Avoid drinking a lot of fluid with your meal (to minimize dilution of stomach acid).
Take a few deep, cleansing breaths before you begin eating and even practice a meal meditation. I like this one from Evelyn Tribole, co-author of the book, Intuitive Eating: "I thank my body for all it has allowed me to do today. I appreciate every cell that works tirelessly for my existence, from my beating heart cells to breathing lung cells. May I nourish every cell, in every organ, to complete satisfaction."
Take a Betaine HCl plus pepsin supplement (consult with a physician and RD before doing so).
Britton, E., & McLaughlin, J. (2013). Ageing and the gut. Proceedings of the Nutrition Society,72(1), 173-177. doi:10.1017/S0029665112002807
InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. How does the stomach work? 2009 Dec 31 [Updated 2016 Aug 21]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK279304/
Lombardo, L., Foti, M., Ruggia, O., & Chiecchio, A. (2010, 2010/06/01/). Increased Incidence of Small Intestinal Bacterial Overgrowth During Proton Pump Inhibitor Therapy. Clinical Gastroenterology and Hepatology, 8(6), 504-508. https://doi.org/https://doi.org/10.1016/j.cgh.2009.12.022
Fossmark, R., Martinsen, T. C., & Waldum, H. L. (2019). Adverse Effects of Proton Pump Inhibitors-Evidence and Plausibility. International journal of molecular sciences, 20(20), 5203. https://doi.org/10.3390/ijms20205203