Report from the LI Conference, part 13

Take a deep breath. You're about to be socked with the longest title and longest list of authors of the whole conference.

Evidence-based Practice Center (EPC) Presentation I: Methods of Systematic Review and the Prevalence of Lactose Intolerance and Differences by Race, Ethnicity, and Age
Timothy J. Wilt, M.D., M.P.H.
Codirector, Minnesota Evidence-based Practice Center
Core Investigator, Minneapolis Veterans Affairs Center for Chronic Disease Outcomes Research
Professor of Medicine
University of Minnesota School of Medicine

Want the full list of co-authors? Here. Timothy J. Wilt, M.D., M.P.H.; Aasma Shaukat, M.D., M.P.H.; Tatyana Shamliyan, M.D., M.S.; Brent C. Taylor, Ph.D., M.P.H.; Roderick MacDonald, M.S.; James Tacklind; Indulis Rutks; Sarah Jane Schwarzenberg, M.D.; Robert L. Kane, M.D.; Michael Levitt, M.D.

They didn't all get up on stage at once, or the auditorium would have become unbalanced and slid into the Potomac. In preparation for the conference, a team of experts combed through all the literature, hundreds, maybe thousands, of studies, to collect every one that looked at various populations. They then did a review of all the applicable studies to see what conclusions could be drawn from everything that had been written on the subject.

Some people say that only double-blinded studies (studies in which neither the testers nor the testees known what exactly what is in the test products) are suitable for drawing serious scientific conclusions. All right, me. I've said it.

Here's the problem. There aren't any. None.

Okay, so this isn't a cancer drug that will decide life or death. Maybe we can go with blinded studies, i.e., those in which just the test subject doesn't know whether there's lactose in the drink or not.

None.

What? That can't possibly be? Nobody has ever bothered to blind-test lactose versus a placebo? The Coke/Pepsi challenge was more rigorous than that.

But the disheartening results give the bad news in so many words.

A total of 54 articles met inclusion criteria, including 15 articles from the United States. Studies did not directly assess LI in a blinded lactose challenge but instead assessed unblinded subjective LI symptoms, an inability to fully absorb lactose (LM), or lactase nonpersistence. The data available tended to be from highly selected populations and were likely not representative of the overall U.S. population. We report results according to the following conditions: LI, LM, or lactase nonpersistence. Within these conditions, we further describe findings according to assessment method and populations studied.

Man, that's ugly.

The truth is that scientists got all hot and bothered about LI when they first started looking around the world and finding it everywhere. Most of those studies took place back in the 1970s. Once they found that lactose malabsorption was common and traced the route that lactase persistence took that made most people in northern Europe milk drinkers, they stopped caring. LI isn't really a medical problem, so the medical community has never been terribly interested in studying all the effects. We just don't get sick enough to make us worth their attention.

Is that good news or bad news?