There is an anatomical reason... at the point where the food pipe (esophagus) connects to the stomach. At this junction is a structure called the the cardiac sphincter . There are a number of reason for this to become incompetent and allow acid from the stomach to enter the esophagus. When acid backflows into the esophagus heart burn is the symptom. This is called acid reflux or Gastroesophogeal Reflux Disease (GERD). The esophogeal tissue isn t able to handle the stomach acid...a burning sensation occurs. When you bend over ...gravity pulls the acid content of the stomach pass the incompetent sphincter. Most common cause is obesity. Abdominal fat pressing/compressing the stomach and pushing it s contents into the esophagus when you bend at the waist. Wearing loose clothing around the waist. Even loosing 5 to 10 pounds can make a big difference. Avoid spicy foods like spaghetti sauce. Eating smaller amounts of food 6 times a day ...instead of 3 large meals can be helpful since overeating distends the stomach and incourages the reflux. Not eating for 4 hours before going to bed is a good idea if you have the problem when you lie down. Some people find sleeping on two pillows or putting the legs at the head of the bed on blocks (to elevate the head of the bed) to work also. Alcoholic drinks also relaxes the sphincter and allows the acid into the stomach so that is something to avoid also. Advancing age is another reason for the sphincter to become incompetent. Some people have a hiatal hernia that exacerbate the signs and symptoms of GERD. There are some over the counter acid suppression medications like; Pepcid AC, Prilosec, Tagamet or Zantac. Ask your pharmacist for help. You can also try a variety of antacids (i.e Tums, Maalox etc.) to neutralize the acids at the time of heartburn occurance . If the problem persists you have to see a doctor...who might prescribe something that would work better like Nexium, Protonix, AcipHex, or Prevacid If you have chronic GERD you can end up with esophagitis or Barrett s esophagus that can lead to esophageal cancer. There are other health problems that have to be considered....chest pain also in the same area as the heart burn can actually be heart releated or a gastric or duodenal ulcer can be the cause of symptoms also. That is why you really should be routinely seeing your doctor. Don t try to self treat...or you could miss some important signs/symptoms of some underlying disease and miss the window of opportunity to treat a very serious disease.