Irritable bowel syndrome (IBS) is a functional bowel disease, which means that anatomically there is nothing wrong with the body, but that the digestive process is working improperly. Controlling the diet is the main treatment for IBS, so many foods must be avoided or reduced to decrease symptoms. Undetected food allergies may exacerbate symptoms, so allergy testing may be recommended. Often individuals must test their tolerance for certain foods on their own and then avoid or reduce the intake of foods that trigger more severe symptoms. Both eggs and coffee have been found to produce symptoms in some people with IBS, though sometimes for different reasons.
IBS has three subtypes: diarrhea-dominant, constipation-dominant, or alternating bouts of either. Many symptoms are common to all types, with the most prevalent being bloating and cramping. Other conditions may stem from IBS, including malnutrition and hemorrhoids. Determining what foods trigger symptoms is often accomplished by keeping a food diary, in which those with IBS write down when they ate what foods as well as what happened as a result. This helps them learn their individual tolerance levels.
Since coffee contains high levels of caffeine, it is considered a stimulant. Stimulants aren't tolerated well by people with IBS. Their digestive systems tend to overreact to stimulants, which brings on more severe symptoms. Some individuals have reported having immediate cramping or diarrhea after drinking coffee. Even decaffeinated coffee sometimes causes problems due to its acidity and an enzyme it contains. Decaffeinated coffee may trigger a milder response than regular coffee, but it often still causes problems due to the other factors.
Many people have egg allergies. Some do not know that they are allergic, if they have a milder allergic reaction. It is possible that some people with IBS have an undiagnosed egg allergy. Another problem that some people with IBS have is foods with sulfur. The sulfur in the eggs, not an allergic reaction, could be what triggers the symptoms. Either way, many people with IBS have problems with eggs.
Talk to your doctor about potential food allergies in an effort to eliminate that possibility. If you don't have allergies, you will have to use trial and error to find out if coffee and eggs are causing your problems. A food diary can help you detect a trend to determine if eggs or coffee are causing the problem. They should not be taken together, because then you won't know which caused the issue. Overall, for most people with IBS, both coffee and eggs are problematic. You may be able to tolerate them on occasion or in reduced quantities.
Sometimes people with IBS may be able to tolerate a food on one occasion, only to have a bad reaction at another time. Other factors may need to be considered, such as stress and hormonal fluctuations. The body may be under stress already and unable to deal with more irritants, such as a potentially difficult-to-digest food, on certain days. Other times you may be able to tolerate the food well because the body is under less stress, so keep those other considerations in mind when choosing which foods to eat.