The diet-microbiome tango: how nutrients lead the gut brain axis.

•Dietary nutrients are important modulators of brain function and behavior.•The microbiome shapes brain function by altering the nutrient content of the diet and producing metabolites from nutrients.•Diet can exert its effect on brain function and behavior by profoundly altering microbiome composition.•Microbiome experiments require a careful control of the host diet and nutritionally specific dietary manipulations.•Diet-microbiome-host interactions are central to understanding how the microbiome shapes brain function and behavior.