Editor,—In his leading article Hills reviews important concepts about a “hydrophobic mucosal barrier” as the main biological basis for protecting the stomach against acid mediated damage to the mucosa (Gut 1996; 39: 621–4). While we support the author’s view that lipid rather than mucus makes the gastric surface less vulnerable to protons, the proposed analogy of this “hydrophobic mucosal barrier” with lung surfactant is supported by little direct evidence. Hills claims that the key molecule of lung surfactant, dipalmitoyl phosphatidylcholine (DPPC), is also the main factor of gastric surfactant, based on indirect measurements some 20 years ago.1

Editor,—In his leading article Hills reviews important concepts about a “hydrophobic mucosal barrier” as the main biological basis for protecting the stomach against acid mediated damage to the mucosa (Gut 1996; 39: 621–4). While we support the author’s view that lipid rather than mucus makes the gastric surface less vulnerable to protons, the proposed analogy of this “hydrophobic mucosal barrier” with lung surfactant is supported by little direct evidence. Hills claims that the key molecule of lung surfactant, dipalmitoyl phosphatidylcholine (DPPC), is …