Q. You recently wrote that “certain fibers can bind essential minerals and lessen their bio-availability.” Could you expand on that? It was of great interest to me, and I bet I’m not the only person wanting to know more.
A. Robert M. Russell, MD, emeritus professor at Tufts’ Friedman School, answers: “It is known that many foods that are high in fiber (particularly cereals) can inhibit the absorption of iron and zinc from the gastrointestinal tract. However, cereals that are high in fiber are also high in a substance known as phytate, which also has an inhibitory effect on these minerals’ absorption. So it is hard to pick apart how much of the inhibition of