What Causes Acid Reflux? Here Are the Known Factors

Acid reflux is a common problem that affects about 20 percent of the population according to the American National Institute of Diabetes and Digestive and Kidney Diseases.1)

The condition occurs when gastric acid leaks upwards into the esophagus through the lower esophageal sphincter. This is a ring of muscle around the lower end of the esophagus where it joins the stomach. It is also known by other names such as esophageal sphincter, gastroesophageal sphincter and cardiac sphincter.

This causes a painful burning sensation just above the sternum. Acid reflux may also present with a sour taste in the throat and mouth, besides small amounts of regurgitated food.

The lower esophageal sphincter normally opens downwards to let food into the stomach after which it closes. This helps to retain the food within the stomach for digestion. Unfortunately, a dysfunction of the lower esophageal sphincter, also called LES can cause it to open upwards, allowing stomach contents to escape into the esophagus.

But what causes acid reflux? Keep reading to find out.

Causes of acid reflux

While it is known that acid reflux occurs when a high amount of gastric acid gets into the esophagus, it is not always clear why this happens. However, there are known factors that lead to acid reflux. These are either the causes or triggers of the condition and include the following:

Hiatal hernia

Hiatal hernia is a structural abnormality in which the lower esophageal sphincter and the top part of the stomach are located above the diaphragm.  The condition may be present at birth or it may develop in the course of life. Excess strain within the abdomen due to an injury, a chronic cough, habitual overeating, constipation, obesity or pregnancy can lead to hiatal hernia.

A normally positioned LES just below the diaphragm is less likely to open into the esophagus because the diaphragm muscles help to keep it closed. However, when your lower esophageal valve is above the diaphragm, it is more likely to open in the wrong direction which can lead to acid reflux.


Some people suffer from an autoimmune condition called scleroderma which causes scarring in connective tissues. If the resultant scarring affects the tissues in the upper digestive tract, it can interfere with the movement of food and the functioning of the lower esophageal sphincter.

This can mean that the LES doesn’t close properly such that gastric acid escapes into the esophagus and causes reflux.2)

Scleroderma can also cause other problems in the digestive system including diarrhea and constipation.


Eating a large meal can end up over-filling the stomach. This increases pressure within the stomach which may cause the lower esophageal sphincter to open in the upward direction, leading to the flow of stomach acid into the esophagus. In fact, most cases of acid reflux occur after meals, and especially if you lie down, go to bed or exercise soon after eating.

You may consider eating smaller meals several times a day instead of eating one or two large meals.


Obesity causes the deposition of a lot of fat in the abdominal area. This can exert excess pressure on abdominal organs including the stomach and the intestines. This can cause gastric acid and small amounts of food to move up through the LES into the esophagus.

If you are a bit overweight and suffer from recurrent acid reflux, you should consider shedding some of it. Studies have found that losing excess weight can reduce the incidences of acid reflux.


Most people are aware of the damage smoking causes in the respiratory tract. But tobacco smoking can also lead to damage in other parts of the body including the digestive system. Tobacco contains thousands of chemicals. When you smoke, these chemicals irritate the throat and the esophagus which leads to the smokers’ cough. 

Recurrent coughing reduces pressure within the esophagus relative to the pressure in the stomach. This can cause the LES to open and release stomach acid in to the esophagus. Smoking also increases the risk of other digestive tract problems including cancers, Crohn’s disease and peptic ulcers.3)

Various studies have found that smokers who suffer from acid reflux can improve their condition if they quit smoking. 


Pregnancy comes with many health challenges including within the digestive system. As the fetus grows, it causes increased pressure within the abdomen. The increase in pressure can cause the lower esophagus valve to open and let stomach contents get into the esophagus. This is the reason why most pregnant women experience acid reflux, heartburn and indigestion, especially in the first trimester.

Considering that eating large meals can also cause acid reflux, it is best for pregnant women to eat several small meals throughout the day instead of two or three large meals.

Hormonal changes during pregnancy can also relax the sphincter and cause acid reflux.

Certain foods

Some people suffer from acid reflux after consuming certain types of foods and drinks. These include greasy foods, spicy foods, citrus fruit, garlic, onion, tomato, pineapple, tea, chocolate, coffee and soda. While most of these foods are acidic, this is not why they cause acid reflux.

They tend to relax the lower esophageal valve such that gastric contents leak into the esophagus. If a certain food ingredient causes your reflux, avoiding it can improve the condition. However, you may need medical assistance to identify the culprit food.


Stress causes or aggravates acid reflux. It is not clear how this happens, but according to some experts, stress can lead to activities that may cause reflux such as overeating, drinking alcohol and smoking. Stress may also cause a person to focus more on the problem which may aggravate the feeling. Reflux may also increase stress which may magnify both conditions.


While medications help in treatment of various ailments, they usually have some adverse effects including acid reflux. People suffer from reflux when they are on different medications including pain killers like aspirin and ibuprofen; sedatives like benzodiazepines; antibiotics like tetracycline and calcium channel blockers used to treat high blood pressure. Mineral supplements for iron and potassium may also cause reflux.

If you are on some medications and have reflux, it is advisable to discuss with a medical practitioner and explore possible alternatives.


Because acid reflux is a common problem, it may be difficult to identify its cause especially when it is chronic in nature. For this reason, you may need to undergo testing and diagnosis at a medical facility.

On the other hand, you can lower your risk of getting reflux by making some diet and lifestyle changes like quitting smoking and excessive intake of alcohol, eating small meals and eating your last meal of the day at least three hours before going to bed.

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