Nickel (Ni) is an essential nutrient for higher animals.  It is found in highest concentrations in lung, kidney and some hormone-producing tissues.

Rich food sources of nickel include oatmeal, dried beans and peas, nuts, and chocolate.

Based on animal experiments, the human requirement for nickel probably does not exceed 100 µg/day.

Although a number of cellular effects of nickel have been documented, a deficiency disease has not been described in man.

Although nickel-specific enzymes have yet to be identified in higher animals, nickel can activate or inhibit a number of enzymes that usually contain other elements. The production or action of some hormones (prolactin, adrenaline, noradrenaline, aldosterone) responds to changes in nickel concentration. Within cells, nickel alters membrane properties and influences oxidation/reduction systems.

It is difficult to induce a deficiency because the requirement is low and nickel comes from a variety of sources.

The levels of other minerals such as iron, magnesium, zinc and calcium may alter nickel absorption from the gut.