TempoLife › Funções › Food compounds: acid load, purines, oxalate and histamine › nickel
Nickel in food: the low-nickel diet and who it is actually for
Nickel is the classic contact allergen — jewellery, belt buckles, phone cases — and by a wide margin the most common one found on patch testing in Europe. A much smaller group of people who are sensitised also react to the nickel they eat, and that is what a low-nickel diet is for.
Not a diagnosis. Nickel allergy is confirmed by patch testing performed by a dermatology service, and a low-nickel diet only makes sense after that confirmation and under supervision — it restricts legumes, wholegrains and nuts, which are foods worth keeping. Widespread or worsening dermatitis needs a clinician, not a food list.
Contact allergy first, diet a long way second
Nickel contact allergy is common — surveys across European populations consistently find it as the leading positive on patch testing, and much more often in women than in men, historically because of ear piercing and jewellery. The EU responded with a restriction under chemicals law that limits how much nickel may be released from articles in prolonged contact with the skin, with a tighter limit for posts inserted into pierced ears, and that restriction measurably reduced sensitisation in younger cohorts.
Systemic nickel allergy syndrome is the much less common step beyond that: a person already sensitised by skin contact develops dermatitis — often on the hands, or in a widespread pattern — and sometimes digestive symptoms, in response to nickel absorbed from food. It is a real phenomenon, but it applies to a minority of nickel-allergic people, and the studies supporting dietary treatment are small.
The order of operations therefore matters. Patch testing confirms sensitisation. Removing the metal sources in contact with skin comes next, because that is where most of the exposure is. Only then does dietary nickel become a sensible thing to investigate, and it should be a defined trial with a defined end.
Where dietary nickel comes from
Plants take nickel up from soil, and the concentration varies with the soil as much as with the species — which is why nickel tables from different countries disagree, and why no table can tell you what is in the lentils you bought. What holds across all of them is the ranking: legumes, especially soy, and wholegrain cereals, nuts, seeds and cocoa sit at the top, while meat, fish, eggs, dairy, refined grains and most fruit sit far below.
A significant part of the exposure never came from a plant at all. Nickel leaches out of stainless steel cookware, and it does so much more when the food is acidic, when the pan is new, and when cooking is long. It also concentrates in canned food, and it accumulates in water that has stood overnight in the plumbing — which is why running the tap for a while before drawing drinking water is standard advice for anyone on a low-nickel diet.
What the safety assessments say
Nickel in food is assessed as a contaminant, not a nutrient. The European Food Safety Authority re-assessed it and derived a tolerable daily intake for the long-term effects, and separately addressed the acute problem — the eczematous flare-up that occurs in already-sensitised people after an oral dose — which needs a short-term reference value rather than a lifetime average. The point of having two values is that the two effects behave differently: one is a chronic toxicological endpoint, the other a same-day immunological one in a susceptible subgroup.
The published figures belong with the opinion they came from, so they are not reproduced here; the assessment is on the EFSA site and is the document to read if you want the numbers.
For practical purposes the useful conclusion is the shape of the problem rather than the number: ordinary diets are not a toxicological concern, and the dietary question is entirely about the sensitised minority.
Nickelpor grupo de alimentos
Faixas, não decimais. Onde uma quantidade publicada para um alimento concreto não pôde ser verificada contra um documento, esta superfície imprime a faixa em vez de um número — e cada alimento abaixo liga à sua própria página de nutrição para ver o que mais há nele.
| Band | O que significa | Exemplos |
|---|---|---|
| Higher nickel | Legumes and soy at the top, then wholegrains, nuts, seeds and cocoa. Actual content varies with the soil the crop grew in, so these are categories rather than measurements. | Soybeans, Tofu, Soy milk, Lentils, Chickpeas, Kidney bean, cooked, Peas, Oats, Oat bran, Buckwheat, Cocoa powder, Dark chocolate, Cashews, Peanuts, Almonds, Walnuts, Flax seeds, Sunflower seeds |
| Lower nickel | Animal foods, refined grains and most fruit and vegetables. These are the staples a supervised low-nickel trial is built around. | White rice, Potato (boiled), Carrot, Cucumber, Apple, Egg (hard-boiled), Whole milk, Cheddar cheese, Chicken breast, Salmon, Butter, Olive oil |
| Not about the food at all | Exposure that comes from the container, the pan or the plumbing rather than from the ingredient. It is often the easiest part to reduce. | Canned tomatoes, canned legumes and other canned foods, Acidic food simmered long in stainless steel, especially in a new pan, The first water drawn from a tap in the morning |
O que muda o número
- Soil is the biggest variable in the plant itself — the same crop from two regions can differ substantially.
- Acidic cooking in stainless steel adds nickel to the dish; enamelled or glass cookware does not.
- New pans leach more than old ones, and the rate falls with use.
- Canning adds nickel; the same food fresh or frozen carries less.
- Running the tap before drawing water clears the metal that leached into standing plumbing.
Onde mais estes alimentos são assinalados
Alimentos elevados nesta página que também se sentam numa faixa elevada em pelo menos duas das outras quinze. Faixas tranquilizadoras não se contam, então uma linha aqui significa que o alimento realmente acumula rótulos mais do que meramente ser mencionado muito.
Vale a pena ler antes de remover qualquer coisa. As listas nesta superfície foram cada uma escritas para uma pessoa diferente com um problema diferente, e convergem no mesmo grupo pequeno de alimentos densos em nutrientes. Satisfazê-las todas de uma vez produz uma dieta que ninguém desenhou e ninguém testou.
Falar com alguém que realmente pode testar
Nothing on this surface is personal medical advice. If a food genuinely makes you ill, if you have had a kidney stone or a gout attack, or if you are considering removing a food group from your diet, the person to talk to is your doctor, pharmacist or a registered dietitian — they can test for the things that can be tested for, which a table cannot.
Fontes:European Food Safety Authority — scientific opinion on nickel in food and drinking water, including the separate treatment of chronic and acute effects. · EU restriction on nickel release from articles in prolonged contact with the skin, under the REACH chemicals regulation. · European surveillance of contact allergy, which consistently ranks nickel first on patch testing.· Nomes de alimentos e ligações: a base de alimentos do sítio. Verificado2026-09-06.
Perguntas frequentes
How do I know if I am nickel allergic?
By patch testing arranged through a dermatology service. Reacting to cheap jewellery is suggestive, not diagnostic, and a low-nickel diet before testing tells you nothing useful.
Does everyone with nickel allergy need to change their diet?
No. Most nickel contact allergy is managed by dealing with what touches the skin. Dietary nickel is only relevant to the smaller group with systemic symptoms, and the evidence base there is limited.
Do stainless steel pans really matter?
They contribute, particularly with acidic food, long cooking and new pans. For someone on a supervised low-nickel trial, switching those dishes to enamel or glass is one of the more effective single changes.
Is a low-nickel diet safe to stay on?
It removes legumes, wholegrains, nuts and seeds, which are among the foods with the best evidence behind them. It should be a supervised, time-limited trial with reintroduction, not a permanent way of eating.
Why do nickel food tables disagree with each other?
Because the content depends on the soil the crop was grown in as well as the species. A number measured in one country does not transfer to another, which is why categories are more honest than figures here.
Outras páginas de composto
Acrilamida
Quem frita, assa ou torra alimento amiláceo
Cumarina
Quem usa muita canela, quem dá canela a crianças, quem toma suplemento de canela
Carga ácida (PRAL)
Formadores de cálculos renais, doença renal crónica, e qualquer um que tenha encontrado a «dieta alcalina»
pH dos alimentos
Conservadores e picles caseiros, qualquer um com erosão dentária, qualquer um confundido por «alimentos alcalinos»
Histamina
Pessoas a investigar rubor e dor de cabeça após refeições; qualquer um que tenha tido uma reação a peixe
Tyramine
People prescribed a monoamine oxidase inhibitor; people told tyramine triggers their migraine
Keep the trial honest
A dietary trial only answers the question if what you ate and how your skin behaved are recorded on the same days. TempoLife does both.