Gastroesophageal reflux (or more commonly known as “acid reflux” or “heartburn”) occurs when food and stomach acid reverses from the stomach back into the esophagus. Usually the Lower Esophageal Sphincter acts as a valve and keeps food on its way down after you swallow. Reflux in infants is common because a baby’s LES is still weak, as the necessary muscles haven’t strengthened yet. Symptoms of acid reflux for adults include a burning sensation in the chest and throat or a bitter, puke-like flavor in the mouth. Some people with frequent symptoms of acid reflux may produce an over-abundance of stomach acid that spills over out of the stomach.