Nickel is an essential trace mineral. Although a number of cellular effects of nickel have been documented, no deficiency disease has been described in humans.

Nickel is found in highest concentrations in your lungs, kidneys, and some hormone-producing tissues. Nickel can activate or inhibit several enzymes that usually contain other elements.

Nickel may play a role in folate and vitamin B12 use to help maintain desirable levels of homocysteine, a toxic amino acid associated with an increased risk of heart disease and stroke. It also influences the production of some hormones, including adrenaline, noradrenaline, prolactin, and aldosterone, which helps maintain blood pressure. Within cells, nickel alters membrane properties and influences oxidation and reduction systems. Nickel is concentrated in cellular structures such as chromosomes and ion channels, but its influence on them at normal concentrations is unknown.

It’s difficult to induce a nickel deficiency, because the requirement is low and nickel comes from a variety of sources. At the cellular level, structures become disorganized and membrane properties change on a low-nickel diet. Nickel deficiency has been linked to low blood glucose levels, abnormal bone growth, poor absorption of iron, and altered metabolism of calcium, vitamin B-12, and energy nutrients.

Your requirement for nickel probably does not exceed 100 µg/day. The nickel content of Western diets ranges from 60 to 260 µg/day.

Foods rich in nickel include: almonds, asparagus, cabbage, cocoa, corn, hazelnuts, legumes, mushrooms, onions, peanuts, pears, raisins, rhubarb, spinach, sprouts, tea, tomatoes, walnuts, and whole wheat flour. You also can get a small amount from water, baking powder, canned foods, and stainless steel kitchen utensils. How much nickel you absorb depends upon the amount you eat, the acidity of your gut, and the presence of binding agents (such as phytate) or competing substances. In particular, the levels of other minerals such as iron, magnesium, zinc, and calcium may alter nickel absorption from your gut.

Toxicity has occurred in refinery workers exposed to nickel, resulting in increased risk of nasal and lung cancers before current workplace safety standards were set. Environmental sources of lower levels of nickel include tobacco, dental or orthopedic implants, stainless-steel kitchen utensils, and inexpensive jewelry.

Repeated exposures may lead to asthma and contact dermatitis, symptoms of which may worsen if your diet is high in nickel. The oral toxic dose is about 1000 times the amount consumed in food. Different chemical forms vary widely in toxicity. Excessive nickel in tissues is oxidizing (damaging chromosomes and other cell components) and alters hormone and enzyme activities, movement of ions through membranes, and immune function. These effects can change glucose tolerance, blood pressure, response to stress, growth rate, bone development and resistance to infection.