Tip: Lemons, oranges and grapefruit have citric acid. These are all citrus fruits. Tip 2: These can all cause heartburn. Not drinking or eating these fruits is the easiest way to prevent symptoms.Note: The acidity itself in the lemonade could cause the acid reflux.This is citric acid. Note 2: Something related to the acidity could relax the lower esophageal sphincter (LES). This causes the acid to go into the esophagus.ot drinking or eating these fruits is the easiest way to prevent symptoms. Note: The acidity itself in the lemonade could cause the acid reflux. This is citric acid. Note 2: Something related to the acidity could relax the lower esophageal sphincter (LES).