Diets high in grains, fiber, and phytates may necessitate a higher zinc requirement than standard RDAs suggest, potentially 50% more for vegetarians.

“if you've got an RDA for zinc for example you take out the fiber and the phytates do you think you actually need the same Zink and even I think even vegetarians have something like 50% more need for zinc than a standard American diet so imagine if you took away all the grains how much sink you would need”