Food, microbes, and medicine all clump together as they move through our gut. Sticky molecules secreted into our intestines bind the gut particles in the same way that flour holds a ball of dough together. Now a new mice-based study from Caltech is showing that dietary fiber also plays a role in clumping. This is the first time that researchers have shown that fiber—stringy molecules found in foods like vegetables and whole grains—helps to aggregate gut particles.