[Mase]

Citric acid is a very weak acid that is used universally because it is highly effective, diverse in it's use, and is cheap to produce.

Even so, the amount used in food and pharmaceuticals is so small that I can't imagine it would have much impact on acid reflux.

[Huck]

Just google “citric acid GERD” and you’ll find that citric acid triggers acid reflux. This includes the many products that contain it as an additive.