From The New York Times:
Stomach acid has long been blamed for acid reflux, heartburn and other ills. But now some experts are starting to think that the problems may lie not just in the acid coming up from the stomach but in the food going down. The idea has been getting a lot of attention lately, notably in popular books like “Crazy Sexy Diet” and “The Acid Alkaline Food Guide” — which claim that readers can improve their health by focusing on the balance of acid and alkaline in the diet, mostly by eating more vegetables and certain fruits and fewer meats and processed foods. While the science behind such claims is not definitive, some research does suggest a benefit to low-acid eating. A handful of recent studies have shown a link between bone health and a low-acid diet, while some reports suggest that the acidity of the Western diet increases the risk of diabetes and heart disease.
This year, a small study found that restricting dietary acid could relieve reflux symptoms like coughing and hoarseness in patients who had not been helped by drug therapy, according to the journal Annals of Otology, Rhinology & Laryngology. In the study, 12 men and 8 women with reflux symptoms who hadn’t responded to medication were put on a low-acid diet for two weeks, eliminating all foods and beverages with a pH lower than 5. The lower the pH, the higher the acidity; highly acidic foods and beverages include diet sodas (2.9 to 3.7), strawberries (3.5) and barbecue sauce (3.7). According to the study, 19 out of 20 patients improved on the low-acid diet, and 3 became completely asymptomatic.