Celiac.com 06/09/2009 - Results of a recent small population study done in Spain suggest that a gluten-free diet may change gut bacteria balance by decreasing beneficial bacteria and increasing detrimental bacteria. Certainly, gut health is an issue to most people with celiac disease. Recent studies suggest that people with celiac disease benefit from bifidium and lactobaccilus supplements, so it's possible that such benefit is in part an offsetting of damage due to gluten-free diet; at least, a connection seems possible.
The Spanish study follows just ten individuals for just one month on gluten-free diets. A large-scale, long-term study might make very different observations, and reach very different conclusions.
The study doesn't provide any real evidence to support a conclusion one way or the other, especially their conclusion that a gluten-free diet "may constitute an environmental variable to be considered in treated Coeliac disease patients for its possible effects on gut health."
The fact is that beneficial, probiotic bacteria in the human gut are influenced by diet. The more fruits, vegetables, and high fiber foods we consume, the healthier our bacteria will be.
The Spanish study makes no mention of the subjects' diets. Were they fed high fiber, low fat diets rich in fruits and vegetables, or did they eat a standard western diet with no gluten?
It would be interesting to compare the gut bacteria levels of people before celiac disease diagnosis and after celiac disease diagnosis to see if a gluten-free diet improves gut bacteria overall, or if the Spanish results would be seen again.