What Causes GERD?
What Causes Gastroesophageal Reflux?
To tell you what goes wrong and causes gastroesophageal reflux, here is a brief description of what happens when things work like they’re supposed to work.
Understanding the Digestive System
The mouth begins to secrete saliva even before we take our first bite. The saliva is an important part of the digestive system as it helps to moisten our food and initiates the chemical action needed for digestion. Saliva mixes with the food as we chew. When we swallow, the tongue forces the food against the roof of the mouth to form a bolus. The food passes down the throat due to the rhythmic action of the pharynx muscles and into the esophagus.
The food continues down the esophagus and into the stomach by strong rhythmic muscle motions that relax and contract in waves, known as peristalsis or peristaltic movement. When the food mixture gets to the lower esophageal sphincter (LES) or valve between the bottom end of the esophagus and the top of the stomach, the LES opens to allow the food into the stomach. The LES valve then quickly shuts tightly.
The stomach is a J-shaped sac and can normally hold about a quart (although it can be, and often is, stretched to hold far more). It takes about eight to ten seconds for the food to make it from the mouth to the stomach. Once inside the stomach, the food mixes with digestive juice, which includes hydrochloric acid.
What Causes Gastroesophageal Reflux
Normally, the LES closes tightly immediately after the bolus has passed into the stomach to prevent the stomach acid from flowing back up into the esophagus. Gastroesophageal reflux occurs when the LES is weakened, thus allowing the stomach acid to flow back into the esophagus or to be regurgitated into the mouth. The stomach acid damages the delicate lining of the esophagus and creates a burning sensation, and possibly a bad taste in the mouth, known as heartburn.
The lower esophageal sphincter is a circular muscle located between the esophagus and the upper part of the stomach and acts as a cut-off valve. The LES normally tightens automatically after food enters the stomach to prevent food and stomach acid from flowing back into the esophagus.
Sometimes, for various reasons, the LES doesn’t close tightly, or the muscle relaxes slightly. The pressure from the stomach causes the valve to open and allows the stomach acid to flow back into the esophagus. This happens to almost everyone at some time or another, but it becomes a medical problem when this occurs more frequently, such as two or more times a week. When this becomes a regular occurrence, it is called gastroesophageal reflux disease or GERD.
Stomach acid seeping into the esophagus and throat can leave a bitter and sour taste in the mouth and creates a burning sensation behind the breastbone that sometimes radiate out towards the neck, throat, and arms. This pain is known as heartburn (though it has nothing to do with the heart). The pain can imitate the symptoms of a heart attack, so it is wise to seek medical attention.
What Are Other Causes of GERD?
There are numerous reasons why stomach acid refluxes into the esophagus, throat, and even the mouth. Here a few:
A physical weakness prevents the LES from closing. A delay in stomach gastric emptying causes the stomach contents to stay longer in the stomach, building up pressure against the LES. This can be caused by medications as well as by other existing medical conditions. Normal aging can be associated with LES muscle tone, although GERD is often found in infants and children.
Diseases such as scleroderma, multiple sclerosis, lupus, and others can cause dysfunction. There can be a reduction in the flow of saliva, which normally neutralizes gastric acid in the esophagus. Traces of acid remain in the esophagus longer, burning the delicate tissue. Lack of saliva can be caused by smoking, certain medications, sleeping, and specific illnesses.
Lifestyle factors, including overeating and overweight, smoking, caffeine, alcohol, and lying down too soon after meals, all may contribute to the LES relaxation, delay in stomach gastric emptying, and a decreased flow of saliva. Medications—prescription, over-the-counter, and even herbal remedies—taken for other existing medical conditions can relax the LES resting tone, affect the flow of saliva, and, in some cases, delay stomach gastric emptying.
Hiatal hernia, while not actually causing GERD, may increase LES relaxation that in turn allows the acid to reflux. A hiatal hernia also may trap or serve as a reservoir for stomach acid, thereby allowing reflux to occur more easily. This permits acid to remain in the esophagus for longer periods, increasing the damage to those tissues.
Since there are so many possible causes for GERD, it can be difficult for your physician to determine the exact cause of GERD in your particular circumstance, so it is very important to be very honest in your physician’s inquiries into your personal habits, such as smoking, drinking, and eating habits.