The next presentation went to the heart of the whole conference. (Why wasn't it first?)
What Is Lactose Intolerance and How To Measure It
Richard J. Grand, M.D.
Professor of Pediatrics
Harvard Medical School
Clinical and Translational Study Unit Director
Center for Inflammatory Bowel Disease
Children's Hospital Boston
[You might remember Children's Hospital Boston from my posts pointing to the research they've done to use injections to reduce milk allergy symptoms.]
What causes the different type, amount, intensity, and duration of lactose intolerance symptoms?
•Quantity of ingested milk
•Fat content of the milk
•Rate of stomach emptying
•Rapidity with which the milk is transported through the intestine
•Individual sensitivity to abdominal discomfort
•Capacity of bacteria in the colon to digest lactose not absorbed in the small intestine
•Psychological impact of anticipation of symptoms in those who have had previous symptoms during milk intake.
Quantity of ingested milk is obvious. The next three are related, and interrelated. As I said on Friday, it's critical to remember that most adults who are lactose malabsorbers still have some residual lactase activity. Anything that slows down the transit time of lactose gives the system more time for the lactose to interact with and be digested by that lactase. Whole bunches of factors regulate how fast food empties from the stomach and goes through the intestines, and one factor that is known to slow transit time is the fat content of the milk.
Items five, six, and seven are also related. The quantity of gases and bloating produced by the bacteria fermenting undigested lactose will depend on what types of bacteria you have and also on how sensitive you might be to intestinal rumblings. Knowing - or thinking that you know - that dairy causes problems might increase your discomfort. And there may be physical differences in your sensitivity to pain. We know for sure that people with Irritable Bowel Syndrome, for example, are far more sensitive to pain and pressure in the colon than people who don't have it. That may also be true for people with LI.
Dr. Grand also explained why an ordinary family physician might not want to send you for formal LI testing. The standard, simple Hydrogen Breath Test costs an average of $773. Somebody has to pay that.