The diaphragm helps the LES keep acid from coming up into the esophagus. When a hiatal hernia is present, it is easier for the acid to come up. In this way, a hiatal hernia can cause reflux. A hiatal hernia can happen in people of any age; many otherwise healthy people over 50 have a small one.

Hiatal Hernia (Hiatus Hernia)(hy-AY-tul HUR-nee-uh)Other factors that may contribute to GERD include
A small opening in the diaphragm that allows the upper part of the stomach to move up into the chest.
Causes heartburn from stomach acid flowing back up through the opening.
- alcohol use
- overweight
- pregnancy
- smoking
Also, certain foods can be associated with reflux events, including
- citrus fruits
- chocolate
- drinks with caffeine
- fatty and fried foods
- garlic and onions
- mint flavorings
- spicy foods
- tomato-based foods, like spaghetti sauce, chili, and pizza
Sources:
Digestive Diseases E -K. National Digestive Diseases Information Clearinghouse (NDDIC). National Institutes of Diabetes and Digestive and Kidney Diseases (NIDDK). NIH Publication No. 00-2750: February 2000
Heartburn, Hiatal Hernia, and Gastroesophageal Reflux Disease (GERD). National Digestive Diseases Information Clearinghouse (NDDIC. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). National Institutes of Health. NIH Publication No. 03–0882: June 2003
Image Credit: NIDDK Image Library. National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC). National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). National Institutes of Health.