Instead, gut bacteria do much of the work, producing helpful substances that support digestion, gut health and blood sugar control. One important type of fibre is called resistant starch. The research team, led by Angela Poole from Cornell University, studied gut bacteria from more than 50 volunteers. Participants ate crackers containing two different forms of resistant starch and, at another time, a normal starch that could be digested without help from gut bacteria. Instead of giving everyone the same dietary advice, doctors may one day recommend foods based on each person’s gut bacteria.