Testing for Stomach Acidity

What is stomach acid?

The digestive process takes place as food passes through the mouth, stomach, small intestine, and large intestine. One of the most important parts of digestion occurs in the stomach, where gastric (stomach) acid helps break down proteins for further digestion in the small intestine.

A healthy stomach has a normal fasting pH (acidity level) between l and 2 (one million times more acid than water). This degree of acidity is required to digest food properly, to absorb some vitamins and minerals, and to ensure proper pancreatic enzyme function. There is an association between too little stomach acid and some health conditions. If there is too little stomach acid, some healthcare practitioners may recommend supplemental hydrochloric acid (betaine HCl), sometimes accompanied by proteolytic enzymes.

The Heidelberg capsule test:

Some physicians measure the stomach’s ability to produce gastric acid with a test called radiotelemetry, using a Heidelberg capsule.1 This test uses a small plastic capsule that is swallowed. The capsule contains electronic monitoring equipment. From within the intestinal tract, the capsule can measure the pH of the stomach, small intestine, and large intestine and transmit a signal, which is received by an antennae worn by the patient. The information gained in this way helps the physician determine whether or not adequate amounts of gastric acid are being produced.

The “self-test”:

In the absence of a laboratory test such as the Heidelberg capsule test, some doctors have the patient try a “self-test.”2 This test is less accurate than the Heidelberg test and should be done only under the supervision of a doctor. The test involves the following steps done over three days.

  • On the first day, upon arising and 30 minutes before breakfast, the patient takes 10 grains (650 mg) of betaine HCl in tablet or capsule form. If any discomfort, nausea, or burning occurs, the betaine HCl is immediately discontinued and the doctor is consulted. If no discomfort occurs, the patient proceeds to step two.
  • On the second day, the patient repeats step one, this time taking two capsules instead of one. If there is any discomfort with two capsules, then the long-term dose is one capsule with each meal. If there is no discomfort, the patient proceeds with step three.
  • On the third day, step one is repeated, this time with three capsules instead of one. If there is any discomfort with three capsules, then the long-term dose is two capsules with each meal. If there is no discomfort, then the dose is three capsules with each meal.
  • Once the dose is determined, that amount is usually taken at the beginning of each meal.


People should not take hydrochloric acid capsules or tablets if they are also taking anything that might irritate the stomach lining. For example, hydrochloric acid should not be taken with aspirin, indomethacin, Bufferin, Anacin, butazolidine, cortisone, or Midol (Tylenol® and Datril® are acceptable). Hydrochloric acid capsules or tablets should not be chewed, because the acid may damage teeth.

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Information expires December 2017.