What Are the Causes of Acid Reflux?

Knowing the conditions that can contribute to acid reflux

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Approximately 25 million adult Americans have acid reflux, or heartburn, on a daily basis, and more than 60 million Americans suffer from heartburn at least once a month. Anyone can suffer from mild and occasional heartburn if they overeat acidic or spicy foods. If they, however, suffer from chronic heartburn that occurs two or more times a week, they may have gastroesophageal reflux disease (GERD).

GERD can be due to various conditions, including abnormal biologic or structural factors. It is important that individuals who suffer from frequent heartburn consult with their physicians to find the cause of their acid reflux, and agree on a treatment plan.

Malfunction of the Lower Esophageal Sphincter (LES) Muscles
The band of muscle located at the junction between the esophagus and the stomach is called the lower esophageal sphincter (LES). This muscle is responsible for closing and opening the lower end of the esophagus and acts as a pressure barrier against the contents of the stomach. If it is weak or loses tone, the LES will not close completely after food passes into the stomach. Stomach acid can then back up into the esophagus. Certain foods and beverages, drugs, and nervous system factors can weaken LES and impair its function.

Abnormalities in the Esophagus
There are some studies that suggest that most people with uncommon GERD symptoms may (such as hoarseness, feeling like there's a lump in the throat, chronic cough) have certain abnormalities in the esophagus that other GERD patients don't.

Impaired Stomach Function
One study has shown that over half of GERD patients showed abnormal nerve or muscle function in their stomachs. These abnormalities cause impaired motility. This occurs when the muscles in the stomach cannot act spontaneously. The muscles do not contract normally, which causes delays in the stomach's ability to empty.

This can increase pressure in the stomach which, in turn, can increase the risk for stomach acid to back up into the esophagus.

Motility Abnormalities.
In normal digestion, food is moved through the digestive tract by rhythmic contractions called peristalsis. When someone suffers from a digestive motility abnormality, these contractions are abnormal. This abnormality can be due to one of two causes: A problem within the muscle itself, or a problem with the nerves or hormones that control the muscle's contractions. Problems in peristalsis in the esophagus are common in GERD, although it is this not clear if such occurrences are a cause or result of the long-term effects of GERD.

Hiatal Hernia
A hiatal hernia occurs when the upper part of the stomach pushes through an opening in the diaphragm, and up into the chest. This opening is called the esophageal hiatus or diaphragmatic hiatus. It is believed that a hiatal hernia can weaken the (LES) and cause reflux. However, studies have failed to prove that it is a common cause of GERD. A hiatal hernia, however, may increase GERD symptoms in patients with both conditions.

Doctors may not completely understand the relationship between asthma and GERD, but most experts do agree there is an important connection.

Some experts hypothesize that the coughing that accompanies asthmatic attacks can cause changes in pressure in the chest, which then can trigger reflux. Certain drugs for asthma that dilate the airways may also relax the LES and contribute to GERD. Likewise, GERD has been associated with a number of other upper respiratory problems and may be a cause of asthma, rather than a result.

Genetic Factors
Studies have suggested there is an inherited risk in many of the cases of GERD. This could be because of inherited muscular or structural problems in esophagus or stomach. Genetic factors may also be an important aspect in a patient's susceptibility to Barrett's esophagus, a precancerous condition caused by very severe gastroesophageal reflux.

Drugs that Increase the Risk for GERD
Nonsteroidal anti-inflammatory drugs (NSAIDs) are common causes of peptic ulcers. They may also cause GERD and increase the symptoms and severity of GERD in people who already have it. In one three-year study of 25,000 people, NSAID users were twice as likely to have GERD symptoms as nonusers. Symptoms did not become evident until after about six months of regular use. NSAIDs include:

  • Aspirin
  • Ibuprofen (Motrin, Advil, Nuprin, Rufen)
  • Naproxen (Aleve)

A point of interest is that NSAIDs have properties that may help to prevent precancerous changes from Barrett's esophagus. The newer NSAIDs called COX-2 inhibitors may prove to be cancer protective in these patients without producing GERD. COX-2 inhibitors include: Celecoxib (Celebrex)Valdecoxib (Bextra).

Other Drugs.
Many other drugs can cause GERD, or increase the severity of symptoms in those who already have this condition. These include:

  • Anticholinergic drugs (urinary tract disorders, antihistamines)
    • Includes natural belladonna alkaloids (atropine, belladonna, hyoscyamine, and scopolamine) and related products.
  • Beta-2 agonists (bronchodilators [Inhalation] -- asthma)
    • Includes Alupent, Bronkaid Mist, Primatene Mist, Proventil, Ventolin, Ventolin Rotacaps.
  • Calcium channel blockers (high blood pressure)
    • Includes Cardizem, Dilacor-XR, Norvasc, Procardia, Vascor.
  • Diazepam (anxiety disorders, seizures)
    • Includes Librium, Paxipam, Valium, Xanax.
  • Nitrates (angina)
    • Includes Nitrogard, Nitrostat, Nitroglyn E-R, Sorbitrate.
  • Opioid analgesics (prescription pain killers)
    • Includes morphine, oxycodone, synthetic opioid narcotics.
  • Theophylline (bronchodilators [oral] -- asthma)
    • Bronchodilators. Includes Aerolate Sr, Choledyl, Respbid, Slo-Bid Gyrocaps, Theobid Duracaps, Theo-Dur.
  • Tricyclic (psychotherapeutic agents, antidepressants)
    • Includes Anafranil, Elavil, Norpramin, Pamelor.