Food allergies affect the digestive system more than any other part of the body because of the close and repeated contact of food with the stomach and intestines. Many people with food allergies suffer from sour stomach or abdominal aches and pains, especially if they're allergic to milk, eggs, wheat, corn, fruit or other frequently eaten foods.

Aside from the annoying and disabling discomfort, digestive problems can be demoralizing – if your doctor doesn’t know you’re allergic, he or she is apt to think you’re hypochondriac. And you might start to believe it! (incidentally, the word hypochondria comes from the Greek word for the upper abdomen).

Indigestion is hard to define precisely. Basically, it's what happens when your food doesn’t get proper treatment after it reaches the stomach. And that can cause various sorts of problems: heartburn, queasiness, or fullness and bloating. Heartburn is simply a colorful way of describing a burning sensation (that sometimes feels like angina) underneath the sternum, the bone in the center of the chest.

Food allergy is often the cause. A related problem is the sensation of having a lump in your throat after you eat. That is caused by a spasm in the esophagus and has been relieved by control of food allergy, says Albert Rowe, Jr., M.D., who has treated people with food allergy for 30 years.

Abdominal bloating, or gassiness, is so characteristic of food allergy that many allergy doctors automatically suspect food tolerance in people who complain that they have to loosen their belts after meals. Abdominal pain, on the other hand, is harder to analyze. It can be dull or sharp, and can spread over the whole trunk or focus on one spot – under the rib cage, behind the navel or in the lower abdomen.

Food induced abdominal discomfort can easily be confused with menstrual pain, stomach ulcers, diverticulosis or gallbladder disease. When other causes have been ruled out, investigation and treatment of food allergy can lead to complete relief. Dr. Rowe reports many cases of allergy related abdominal pain.

One man, for instance, had pain in the lower and middle left abdomen every night around 3:00 or 4:00 A.M., which was relieved be avoiding foods to which he was allergic. A woman experienced pain across the upper and middle abdomen for six weeks until wheat was excluded from her diet.

If the allergy is severe, the slightest dietary infraction – often from an unsuspected source – can trigger an attack. One of Dr. Rowe’s patients who was allergic to eggs had a severe ache across the upper abdomen within one hour after eating candy that contained a trace of egg. The pain lasted 18 hours.

”These abdominal symptoms are best explained by allergic inflammation and muscle spasms causing disturbances in the stomach, esophagus and other digestive organs,” Dr. Rowe points out as the coauthor of the book, Food Allergy (Charles C. Thomas, 1972).

”Burning, bloating and belching, for which antacid tablets and liquids are used by thousands of people daily, can be controlled when the offending food are eliminated – thus making those medications unnecessary.” Complete guidelines for tracking down food allergies appear in Are Your Allergic?, and Rotary Diets.