DEAR DR. DONOHUE: I have a super active digestive system and have had it for most of my life. Within an hour after any meal, it has passed through my system and is ready for elimination. Is this normal? – D.C.

DEAR DR. DONOHUE: Fifteen to 20 minutes after I eat, I get diarrhea. Even toast and coffee in the morning give me the runs. I am afraid to take any long trips because of this. Please help. – A.G.

ANSWER: Normally, it takes food a day and a half to two days to pass through the digestive tract. Naturally, liquids pass more rapidly than solids. The stomach empties in one to four hours; it takes three to six hours for food to pass through the small intestine; the remainder of the time is spent in the journey through the colon.

D.C.’s problem has been lifelong and apparently hasn’t caused any major health problems. A.G.’s problems are evident. After eating, the digestive tract experiences peristaltic waves, coordinated muscle contractions of the digestive tract that pushes food downward. D.C. might have exceptionally strong peristalsis and the food from yesterday may be propelled downward more forcefully and more quickly than normal.

A.G. might have a number of conditions. Irritable bowel syndrome can bring about diarrhea shortly after eating. Impaired function of the vagus nerve is another cause of rapid transit through the tract. An overactive thyroid gland is a possibility.

Illnesses that interfere with food absorption give rise to rapid emptying of the tract. Celiac disease – an inability to digest gluten, a protein in wheat, barley and rye – is one example. A loss of the enzyme that digests milk sugar – lactase deficiency – is another. Pancreas malfunction, gallbladder trouble, inflammation of the digestive tract (Crohn’s disease and ulcerative colitis) all can cause these symptoms.

A gastroenterologist is the doctor who can lead both of you through the maze of tests necessary to obtain a diagnosis. In the meantime, experiment. Cut back on the amount of carbohydrates and the volume of fluid you take at mealtime. Stop drinking caffeine. Eliminate dairy products. Eat six small meals rather than two or three large ones.

DEAR DR. DONOHUE: My wife has cryptogenic organizing pneumonia. She is on prednisone. Please explain this disease, its cause and its cure. – L.V.

ANSWER: “Pneumonia” indicates that the lung’s air sacs and breathing passages are inflamed. The common pneumonias are caused by bacteria and viruses. Your wife, however, has lung inflammation whose cause is unknown (“cryptogenic”). “Organizing” indicates the air sacs and breathing passages are filled with loose tissues. This pneumonia occurs in the fifth and sixth decades of life, and its onset is highly suggestive of flu, with a dry cough, fever and washed-out feeling. Weight loss often is part of the picture. The cough is persistent. Prednisone is a cortisone drug, the most powerful inflammation fighter. Two-thirds of patients are effectively treated with it. Other anti-inflammation drugs, like cyclophosphamide, can be added if prednisone doesn’t stop symptoms. A few people respond to neither treatment.

DEAR DR. DONOHUE: Is it appropriate, safe and effective for someone who has had a previous shingles outbreak and has genital herpes to take the shingles vaccine? – H.B.

ANSWER: Yes to both.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.