When Acid Rises (2 Letters) Re "Combating Acid Reflux May Bring Host of Ills" (The Consumer, June 26): Some doctors believe that acid reflux can be caused not just by too much stomach acidity but too little (resulting in inadequately digestion), or by a stomach that has proper acidity but empties too slowly. In the latter case, proton pump inhibitors, or P.P.I."s, may not be the treatment of choice, and in the former they would make the condition worse. Stomach acidity can be measured by inserting a tube, an uncomfortable and expensive procedure. The government is conducting clinical trials on a disposable wireless capsule that is swallowed by the patient and transmits pH, temperature and pressure to an external receiver as it passes through the system. Aron Yoffe Los Angeles The excellent article on acid reflux did not mention an alternative therapy: a combination of alginic acid and bicarbonate (Gaviscon), which creates a foam barrier to help prevent reflux. This remedy does not change the ecology of the gut and does not reduce the production of stomach acid, but prevents it from rising. It's an example of how simple over-the-counter treatments are sometimes more effective than newer medicines that create new side effects and new problems. Michael R. Reich Barbara M. Field Brookline, Mass.