For overweight people, the act of bending down squeezes the stomach and excess fat around the stomach, forcing food and acid in the wrong direction. If you want to prevent heartburn -then don't smoke or drink alcohol - they are both irritants and tend to increase the amount of acid your stomach produces - and don't eat late at night, or you'll go to bed and lie flat with a distended stomach that's busy making acid to digest the food.
Very fatty, spicy or cold foods may well make matters worse. Avoid coffee, cucumbers, onions or anything else which you find brings on heartburn and don't wear tight belts or clothes, which will squeeze you just in the right place to bring on the symptoms of heartburn.
Do eat smaller meals and try to lose a few pounds if you are overweight. Also, take care when you bend down - if you keep your back straight, you won't squash the contents up and out of your stomach.
Many articles taken from 'A word with the doctor', by Dr. John Windsor.