Shirley S. Wang wrote a nice piece in the Wall Street Journal on lactose intolerance.
Most people continue to produce some lactase, but at much-diminished levels. After they reach their individual threshold and can no longer break down lactose, it passes intact through the intestine until it reaches the colon, where it is finally fermented by the bacteria that reside there. As the bacteria do their job, they produce gas as a byproduct, which causes discomfort and pain as well as symptoms such as cramping and diarrhea.
Training the Bacteria
Some people, after diagnosing themselves, cut out regular consumption of dairy—which can potentially make symptoms worse when they do consume it. The bacteria in the gut can become less efficient at processing lactose if they aren't continually asked to do it. Conversely, people can train the bacteria to tolerate more dairy if they consume it regularly.
She goes on to talk about some of the genetic research into lactose intolerance. In fact, it's clear that she did the interview with Eric Sibley, an assistant professor of pediatrics at the Stanford University School of Medicine, and then wrote an article to justify it.
It's telling that even a well-written, informed article such as this can have so much wrong with it.
Amazingly, Wang never mentions that lactase pills have been available for decades and they are far more effective for far more people than trying to retrain the gut bacteria.
And then there's this:
Dairy products that have gone through some processing, such as cheese and ice cream, tend to have less lactose because the fermentation process breaks some of it down. But those with an intolerance should keep an eye out for lactose that has been added to products like cookies by reading the food label, says Gilman Grave, acting director of the National Institute of Child Health and Human Development's Center for Research for Mothers and Children.
Keeping an eye on ingredients lists is certainly important. But what's that about ice cream being fermented or having less lactose? That's completely wrong. She might have been thinking about frozen yogurt, but that's an extremely odd mistake to make.
We have a long way to go.