Nickel in Foods: Always Calculate the Portion

Nickel in foods is an important factor to consider for those who are sensitive or allergic to this metal. While many cereals can contain nickel, it is essential to know and monitor the amount present in the foods we consume. Some cereals, such as quinoa and teff, stand out for their low nickel content, containing about 1.7 micrograms per 100 grams of product.

Guide to Reading

1. What does it mean to be allergic to nickel?
2. Nickel: how we come into contact with it
3. Nickel accumulation
4. Symptoms of nickel allergy

1. What Does It Mean to Be Allergic to Nickel?

Nickel allergy affects about 15% of the European population, with an average of three women affected for every man. It can appear from early childhood and persist throughout life. This is referred to as Systemic Nickel Allergy Syndrome (SNAS), which can involve both contact allergic dermatitis (CAD) and reactions related to nickel ingestion.

A 2014 study (Ricciardi L, Arena A, Arena E, Zambito M, Ingrassia A, Valenti G, Loschiavo G, D’Angelo A, Saitta S. Systemic nickel allergy syndrome: epidemiological data from four Italian allergy units. Int J Immunopathol Pharmacol) examined the correlation between the two, confirming it in 16 out of 98 patients. The research indicates that further investigation is needed and that CAD is not necessarily linked to dietary allergy. Therefore, having a contact allergy to nickel does not automatically mean you will also develop a food-related allergy.

2. Nickel: How We Come Into Contact

Nickel is found in certain objects (jewelry, coins, kitchen utensils, keys, metal tools, etc.), cosmetics (cleansers, mascara, lipstick, eyeshadow), some foods, and water. The nickel content in plant foods can vary depending on soil type and cultivation methods.

Traditional fertilizers used in conventional agriculture contain heavy metals, and tolerance regulations vary by country. For example, in Spain, Law 12731 of May 28, 1998, allows a nickel level of 120 mg/kg, while Italian regulations (All. 1 C D.M. 27/03/98) limit it to 50 mg/kg.

It is important not to generalize by avoiding certain foods entirely. Instead, awareness allows us to distinguish which foods are safe. Note that nickel is prohibited as an added ingredient in cosmetics and personal care products (EU Regulation 1223/2009) but may occur as a contaminant in raw materials and therefore is not required on the INCI list. Some companies conduct specific tests to ensure consumer safety.

3. Nickel Accumulation

Nickel allergy is considered cumulative because excessive intake or poor elimination can trigger allergic reactions even in small amounts.

A 2011 study found that 74% of SNAS patients also had lactose intolerance, compared to only 6% in the control group (Cazzato IA, Vadrucci E, Cammarota G, Minelli M, Gasbarrini A. Lactose intolerance in systemic nickel allergy syndrome. Int J Immunopathol Pharmacol. 2011 Apr-Jun).

In 2020, the EFSA (European Food Safety Authority) updated its scientific opinion on health risks from nickel in foods and water. The limit increased from 2.8 µg/kg of body weight to 13 µg/kg of body weight. To calculate your personalized limit, multiply 13 by your body weight. Note: this is not your tolerance threshold but the amount you should not exceed in one day. EFSA experts concluded that chronic dietary exposure to nickel may be a concern for younger age groups (infants and children).

4. Symptoms of Nickel Allergy

I sintomi dell’allergia al nichel compaiono appena ingerito l’alimento ed entro le successive 48 ore. Symptoms usually appear shortly after ingestion and within 48 hours. They include:

• General: fatigue, weakness, malaise
• Topical: redness, rashes, dermatitis
• Gastrointestinal: bloating, abdominal pain with cramps, diarrhea or constipation, mouth ulcers, gingivitis, mucus
• Urinary: burning, episodes of cystitis
• Gynecological: itching, discharge, recurrent candidiasis
• Hair and nails: hair loss, brittle nails
• Neurological: headache, dizziness, vertigo, tingling in limbs, cramps
• Other: bloating, water retention

Even mild reactions, such as sneezing, should not be ignored. Always correlate symptoms with recent food or drink intake.

Nickel and Dysbiosis

Nickel can affect gut microbiota, reducing Bifidobacteria and/or Lactobacilli. It may be a manifestation of SIBO (Small Intestinal Bacterial Overgrowth) and can contribute to intestinal permeability. In some people, nickel triggers an abnormal immune response, increasing eosinophils (white blood cells that combat allergies and infections). Nickel sensitivity is also linked to anemia because it competes with iron absorption in the intestine.

Pay Attention to Quantitative Data: Always Calculate the Portion

Online resources often provide qualitative nickel information (high, low, etc.), which is approximate and may unnecessarily limit dietary variety.

For example, tea is often labeled high in nickel (~450 µg/100 g). A tea bag weighs 2 g, containing 9 µg of nickel, about the same as half a pear (an allowed food). Some teas contain up to 750 µg/100 g (~15 µg per tea bag), roughly equal to 60 g of store-bought gnocchi. Only quantitative values allow informed decisions.

The same applies to oats, which are often excluded without considering actual nickel content. For example, 30 g of rolled oats for porridge contain:

(96÷100)×30=28.8µg

This is roughly the same as 1 pear or 7 g of dark chocolate (1 square ≈ 10 g).

Measuring portions allows better awareness and safer dietary planning.

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Examples of Nickel Content in Foods (µg per 100 g)

To follow a low-nickel diet, consult professionals and calculate intake using quantitative data.

Article by Monia Caramma
Sustainable Food Researcher

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