The best thing you can do to increase the stomach acid is to find the cause that is suppressing it, and correct it when possible. L Histidine is probed to increase the perietal cell secretion when taken twice a day during meals. Atrophic Gastritis caused by long term H. Pylori damages the parietal cells and suppress the acid secretion. An autoimmune disease that attack the parietal cells and destroy them is another cause. Immune suppression also cause lack of stomach acid by unknown reasons. Some researchers believe a severe stress is another causative factor. Any acute or chronic kind of gastritis is able to suppress the gastric acid output. Easy to say but hard to correct. I have this problem and I don't know what is causing it. I don't have the money to pay all the medical tests to identify the cause.
Jorge.