HCL, or hydrochloric acid, is a compound produced by the stomach that is involved in the digestion and absorption of food.
As a supplement, HCL is promoted to increase stomach acid, which in turn should theoretically lead to improved digestion and absorption of nutrients, especially in people who suffer from hypochlorydria (the medical term for low stomach acid1).
In this article, I will review the causes of low stomach acid, what the symptoms are, why it is dangerous, how it is diagnosed, and, finally, discuss the pros and cons of supplementation with HCL.
While there are many rare causes of this condition, here are some of the more common ones:
1. Certain medicines, like antacids (Tums) and proton pump inhibitors (Nexium), which are often used to treat excess stomach acid, lower stomach acid by design. This is desirable when stomach acid is actually high. The problem here is in the fact that many of the symptoms of too much stomach acid and too little overlap, and if you have low stomach acid mistakenly diagnosed as high stomach acid these medications will make your situation worse.
2. Hypothyroidism can lower basal metabolic rate and decrease stomach acid production.
3. Autoimmune diseases in which the body creates antibodies, which attack the cells that secrete acid.
4. Infections like H. pylori, which is also associated with stomach ulcers, lower acid output.
5. Surgeries involving the stomach, like the classic gastric bypass procedure (roux en y) cause hypochlorhydia.
6. Deficiencies of certain minerals, which are necessary to produce acid, can decrease levels.
Since HCL is required for proper food absorption, inadequate levels can lead to bloating, gas, diarrhea and burning or discomfort in the stomach or throat. Low HCL can lead to overgrowth of harmful bacteria (the acid in the stomach has an immune function as well as a digestive function) and multiple vitamin and mineral deficiencies including B12, vitamin K, magnesium and iron.2 HCL deficiency is associated with stomach cancer and asthma. As you can see, the consequences of low stomach acid are many and often life threatening.
If you have any of the signs or symptoms described above, it is worthwhile to look into it further. Additionally, if you’re being treated for acid reflux with medicine, you should certainly discuss this possibility with your doctor, as many people are incorrectly placed on acid suppressing medications when too little acid is actually the problem.3
The best way to know if you have hypochlorhydia is to have your stomach acid levels directly checked. This usually involves monitoring the pH of stomach secretions over a 24 hour period. Your doctor may order other tests as well, such as levels of antibodies against the stomach’s acid-secreting cells.
While there are a lot of “home tests” out there, none can match the reliability of direct measurement and lab work. The Heidelberg stomach acid test protocol involves swallowing a pill that records the pH of your stomach while you drink a solution of sodium bicarbonate (baking soda). Another “home test” requires you to drink baking soda and record the time until you burp. I could not find any data to support this test’s reliability. Charles Poliquin, a well-respected strength coach has his own testing protocol4 as well, though I could not find any scientific basis for it.
Since low acid production can cause life-threatening illness, if you suspect you have it then you should see a physician. And since HCL supplementation can be detrimental to health in certain people, I recommend talking to a health care practitioner who is knowledgeable in this area before treating.
If low acid secretion is associated with a certain bacteria (H. pylori), then eliminating the bug can remedy the situation. Additionally, it is wise to supplement any nutrient you are deficient in because of low stomach acid. In the case of B12 deficiency, injections may be necessary.
As far as using an HCL supplement, there are certain risks. If you have a gastric ulcer or are taking nonsteroidal anti-inflammatory medications like Motrin or Aleve, your risk of bleeding is increased. Excess acid can contribute to heartburn symptoms and esophageal damage.
The benefits of HCL supplementation include improved digestion and absorption of vitamins and minerals and may relieve reflux symptoms (if they’re related to low acid), decrease bloating and improve feelings of well-being.
Despite the fact that millions of people have been using natural acid promoting substances for hundreds of years, I could not find any peer-reviewed literature examining risks and benefits of supplementation. Unfortunately, and I am going to try not to sound like a total conspiracy theorist, there is no money to be made in doing this type of research, as natural substances like HCL cannot be patented and are essentially available to anyone.
Some people even go so far as to say medical students are taught mostly about acid excess (which can be treated with pharmaceuticals) and not acid insufficiency, which cannot. Jonathon Wright, a Seattle-based function medicine physician wrote: “Encouraged by the legal drug industry, medical students are not taught that hypochlorhydria (inadequate stomach acid production) is treatable only with unpatentable, natural replacement therapies. Instead, their education concentrates on hyperchlorhydria (excess stomach acid production) and its treatment with patentable acid blocker drugs and highly profitable over-the-counter antacids.”5
Given the potential gravity of low stomach acid, I strongly encourage you to find a knowledgeable practitioner to discuss supplementation with. If you decide to use an HCL supplement, I would get one with pepsin (another digestive compound made in the stomach), as this will improve the effectiveness of the HCL. SOLRAY and NOW Foods both make HCL/Pepsin combos