MedicalResearch.com Interview with: Prof. Avraham A. Levy Department of Plant and Environmental Sciences Prof. Eran Elinav Department of Immunology Prof. Eran Segal Department of Computer Science And Applied Math Weizmann Institute of Science, Rehovot Israel MedicalResearch.com: What is the background for this study?  Response: We performed a type of clinical trial that is very powerful in comparing short term effects of interventions - a crossover trial. In this trial, each subject is compared to themselves; in our case, we compared increased short-term (1 week) consumption of industrial white bread vs. matched consumption of artisanal sourdough-leavened whole-wheat bread - which we originally viewed as radical opposites in terms of their health benefits. We measured various clinical end points - weight, blood pressure, various blood tests - and also the gut microbiome. To our great surprise, we found no difference between the effects those two breads had on the various end points that we measured. This does not mean that bread consumption had no effect - but that this effect was generally similar for its two types. In fact, when we analyzed our data when pooling together the two bread types (i.e., testing whether bread of any type had an effect), we found that just one week of bread consumption resulted in statistically significant changes to multiple clinical parameters - on the one hand, we saw a reduction in essential minerals in the blood (calcium, magnesium, iron) and an increase in LDH (marker of tissue damage); on the other hand, we saw an improvement in markers of liver and kidney function, inflammation markers and cholesterol levels. In terms of the microbiome, we have found only a minimal difference between the effects of the two bread (two microbial taxa that were increased with white bread) - but in general, we saw that the microbiome was very resilient to this intervention. This is surprising as the current paradigm in the field is that a change in nutrition rapidly changes the makeup of the microbiome. We say that this is probably dependent on the kind of change - as we had a nutritional change here which was significant enough to change clinical parameters, which we tend to think of as very stable, and yet had a minimal effect on the microbiome. At this point, there were two possible explanations to what we saw: The first is that bread had an effect in our intervention, but it was very similar between those two very distinct types. The second is that these two distinct types indeed had different effects, but they were different for each subject - and thus cancel out when we look at the entire population. (more…)