Gastroesophageal Reflux Disease (GERD) is a common condition where stomach contents flow back up into the esophagus. This backward flow, known as reflux, can cause bothersome symptoms or lead to complications over time. While occasional reflux happens to many individuals, GERD is characterized by its persistence and severity, indicating a more significant underlying issue.
The Esophageal Barrier
The body has natural defenses to prevent stomach contents from re-entering the esophagus. The primary barrier is the lower esophageal sphincter (LES), a ring of muscle located at the junction of the esophagus and stomach. This muscle maintains constant contraction, acting like a valve that opens only to allow swallowed food and liquids into the stomach or to permit burping.
Other anatomical structures also contribute to this barrier. The diaphragm, a muscle involved in breathing, wraps around the esophagus at the LES, providing external compression that reinforces its closure. The acute angle where the esophagus joins the stomach, known as the angle of His, creates a flap-like valve that helps prevent reflux. These mechanisms ensure stomach acid and other contents remain where they belong.
Mechanisms of Reflux
When esophageal barriers fail, stomach contents can reflux, leading to GERD. Transient LES relaxations are brief, spontaneous openings of the sphincter unrelated to swallowing. These are the most frequent cause of reflux episodes in GERD, allowing stomach acid to surge upwards. The LES may also suffer from hypotonia, meaning it is too weak to maintain adequate pressure against stomach contents.
Impaired esophageal clearance is another mechanism. After reflux, the esophagus clears acidic contents back into the stomach through peristalsis, a wave-like muscular contraction. If clearance is inefficient, the esophageal lining remains exposed to acid longer, increasing irritation. Delayed gastric emptying, where food stays in the stomach longer, also contributes by increasing the volume and pressure of stomach contents available for reflux. A hiatal hernia, where part of the stomach pushes up through the diaphragm, can disrupt normal anatomy, weakening the LES’s function and creating a reservoir for refluxed material.
The Impact of Reflux on the Esophagus
When stomach contents, primarily acid and pepsin, repeatedly reflux into the esophagus, they cause irritation and inflammation of the esophageal lining. This lining, unlike the stomach’s, is not designed to withstand acidic environments. Prolonged exposure leads to esophagitis, inflammation of the esophageal epithelium. Esophagitis manifests as discomfort or pain, often described as heartburn, and may cause difficulty swallowing.
Chronic inflammation can lead to tissue damage over time. Constant assault from stomach acid can result in erosions or ulcers, open sores on the esophageal lining. In some cases, the body may adapt to persistent acid exposure by changing the cells lining the esophagus, known as Barrett’s esophagus. While this cellular change is a protective response, it is associated with an increased risk of esophageal adenocarcinoma.
Contributing Factors to GERD
Several factors can contribute to or worsen GERD by increasing reflux events or reducing esophageal barrier effectiveness. Dietary choices play a role; certain foods and beverages, such as fatty or fried foods, spicy dishes, citrus fruits, tomatoes, chocolate, caffeine, and alcoholic beverages, can relax the LES or stimulate increased stomach acid production. Consuming large meals, especially close to bedtime, can distend the stomach and increase LES pressure, making reflux more likely.
Lifestyle factors also contribute to GERD. Obesity significantly increases abdominal pressure, which can push stomach contents upwards against the LES. Smoking is another factor, as nicotine can directly relax the LES and impair saliva production, which helps neutralize acid. Pregnancy can also lead to GERD due to hormonal changes that relax the LES and increased abdominal pressure from the uterus. These elements can individually or collectively compromise the body’s natural defenses, exacerbating reflux symptoms.