Trace metals are metals in extremely small quantities, almost at the molecular level, that reside in or are present in animal and plant cells and tissue. They are a necessary part of good nutrition, although they can be toxic if ingested excess quantites.
Trace metals are depleted through the expenditure of energy by a living organism. They are replenished in animals by eating plants, and replenished in plants through the uptake of nutrients from the soil in which the plant grows.
Trace metals are sometimes referred to as trace elements, though the latter is a broader category. See also Dietary minerals