Bread Affects Clinical Parameters and Induces Gut Microbiome-Associated Personal Glycemic Responses.
Level 2 - randomized trial
Randomized crossover trial in humans
PubMed 28591632 · doi:10.1016/j.cmet.2017.05.002
What was done
Investigators conducted a randomized crossover trial comparing two 1-week dietary interventions: traditionally made sourdough-leavened whole-grain bread versus industrially made white bread. They evaluated changes in multiple clinical parameters, gut microbiota composition resilience, and interpersonal variation in glycemic responses. The number of participants was not stated in the abstract.
What was found
The abstract reports no numerical data, confidence intervals, or exact p-values. It reports no statistically significant differential effects of bread type on multiple clinical parameters, and gut microbiota composition remained person-specific and resilient. However, there was statistically significant interpersonal variability in glycemic response between bread types, and pre-intervention microbiome data alone successfully predicted which bread type elicited a lower glycemic response for a given individual.
Why it matters
The study shows that population-wide nutritional generalities about whole-grain versus refined bread can mask marked personal metabolic differences. It suggests that dietary interventions may need to be tailored using baseline gut microbiome data.
Limits
The abstract omits the sample size, participant characteristics, washout duration between phases, and all quantitative outcome measurements. In addition, each intervention lasted only one week, which precludes assessment of long-term clinical and microbiota effects.
Cited by
- supports Individual glycemic spikes vary widely across different carbohydrate sources, partly driven by the gut microbiome.