Weakened LES
The lower esophageal sphincter (LES) acts as a flap to prevent acid, food and bile from flowing back up the esophagus from the stomach. The esophagus is a tube that connects the mouth to the stomach. When the LES is abnormally relaxed or weakened, it can allow stomach acids to return from the stomach, causing a burning sensation in the chest and throat. As the Mayo Clinic points out, faulty LES function may be exacerbated by other conditions, but the initial weakness or relaxation of the LES is difficult to identify. Chronic acid reflux can cause more damage to the LES, making it weaker.
Pressure
Pregnancy can make the symptoms of acid reflux worse than usual, or it can lead to acid reflux in someone who never experienced it before. The reason for this is that the pressure of the growing baby on the stomach forces stomach acids back up the esophagus. Wearing tight clothes can also put pressure on the stomach, leading to the same result.
Eating Habits
Certain foods have a higher likelihood of producing extra acid that can contribute to reflux. Foods with this potential include caffeine, alcohol, fatty foods, citrus foods and spicy foods. Other foods may be just as guilty, but will depend on the individual's sensitivity to a particular food. Large meals overfill the stomach, slowing the digestion process and creating a buildup of acid.
Gravity
Bending over after eating may relax the LES, causing acid to return to the esophagus and larynx. Eat the last meal of the day several hours before bed, as acid will not have to fight gravity to flow back up the esophagus when the body is prone in bed. Individuals who experience substantial reflux while sleeping may find it helpful to sleep with their upper body at an incline.
