The Nutrition Source

Nickel

vinegar being poured into a stainless steel pan

Nickel is a ubiquitous mineral found in soil, water, and air. In the human body, it is a component of certain enzymes involved with chemical reactions and may assist with iron absorption. The absorption of nickel can depend on specific foods it is eaten with, including milk, tea, coffee, and orange juice, which either increase or decrease its absorption. However, studies suggest that the overall absorption of dietary nickel is low, at less than 10%, and the majority of ingested nickel exits the body in urine or stool. [1] Nickel is not stored in most tissues or organs, with the exception of the thyroid and adrenal glands.

Recommended Dietary Allowance

Research regarding the nutritional importance or biochemical function of nickel in the human body is not available. Therefore, a Recommended Dietary Allowance or Adequate Intake has not been set. [1]

Food Sources

Nickel is found mainly in plant foods that absorb nickel through soil and water. The amount of nickel in a food depends on the nickel content in the soil in which it was grown. Therefore, even the same food can vary in nickel content regionally. Cooking acidic foods in stainless steel utensils may increase their nickel content.

The following foods have been found to have higher nickel content:

Toxicity

There is no evidence of harmful effects of nickel obtained in the diet. The few cases of negative symptoms of gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain) of excess nickel intake occurred from accidental ingestion from contaminated water. [1]

Allergic reactions to nickel

Hypersensitivity to nickel is a major cause for allergic contact dermatitis, a skin irritation that creates an itchy rash. Sensitivity occurs when the skin’s surface has prolonged or repeated contact with nickel such as in jewelry. A food allergy to nickel, referred to as systemic contact dermatitis or SCD, is sometimes suspected if dermatitis is present without known contact with other allergens. However, following a nickel-free diet is impossible as it is found in trace amounts in a wide variety of commonly eaten foods and seafood. It is also very difficult to accurately measure nickel content in food due to regional variations in nickel content of soil and water, and it varies by plant species. [2] Another challenge causing conflicting measures of nickel is the different types of tests used to measure nickel in food. Sometimes nickel from food processing machines can leach into food. Cooking acidic foods (tomatoes, vinegar, citrus) in stainless-steel cookware can increase its nickel content. Generally, the foods most often found to contain nickel include legumes, soybeans, chocolate, nuts, sunflower seeds, oats, and granola. [3]

People who are iron-deficient may absorb more nickel from the diet, as iron and nickel compete for absorption in the body. Therefore to reduce nickel absorption, it has been suggested to eat iron-rich foods and vitamin C (which improves the absorption of iron) with meals.

Treating SCD with a low-nickel diet remains controversial. A Recommended Daily Allowance for nickel has not been set, so it is unclear what amount of dietary nickel may reduce symptoms of dermatitis. [4] Some studies estimate that people eat about 220-350 micrograms of nickel daily, so a restriction of less than 150 micrograms daily has been suggested for adults with suspected SCD, and less than 100 micrograms daily for children. The Low-Nickel Diet Scoring System with a points method was established to help those with SCD reduce dietary intake of nickel. [3] The Academy of Nutrition and Dietetics reports that following a low-nickel diet for 4-6 weeks is adequate to determine if nickel is a cause for SCD. [5]

Related

Vitamins and Minerals

Last reviewed March 2023

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