Why Zinc Deficiency Is So Common Zinc is present in many foods but its bioavailability varies enormously depending on what those foods are and what they're eaten with. Red meat, shellfish (particularly oysters β€” the richest dietary source by far), and animal products generally contain highly bioavailable zinc. Plant-based sources like wholegrains, legumes, and nuts contain reasonable quantities of zinc but also contain phytates β€” compounds that bind zinc and reduce absorption by 15–65%. As plant-based eating has increased and processed food consumption has risen (processed foods typicall…