Hey ,

pH and the amount of stomach acid are closely related, but not the same. When the pH is below 7 this means that a solution has a certain acid concentration. The amount of stomach acid refers to the amount of liquid produced by the stomach. 

So the pH can change during eating a meal. If you add water, for example, the pH goes up and the concentration of acid goes down, while the amount of acid stays the same.

With low stomach acid(hypochlorhydria), we mean an elevated pH caused by a lack of stomach juices and yes, it influences the LES as well as the pyloric sphincter.

The opening and closing of the pyloric sphincter is depending on stomach acid production, but it depends on other factors as well like:
• The volume of the food in the stomach.
• Some foods trigger certain hormones like gastrin & cholecystokinin that influence the opening and closing of the pyloric sphincter.

Gastritis can be caused by bile reflux, but keep in mind it isn’t the only reason. It can also be caused by: other bacterial and viral infections, spicey foods, extreme stress, chronic bile reflux, autoimmune disease, injuries, operations, etc. On top of that it could be a combination of those.

While SIBO can cause gastritis I always like to keep an open mind and use a multifactorial approach.