Nickel allergy is the manifestation of an adverse reaction of the body to this metal.
There is talk of allergy as activation of the immune system occurs, resulting in inflammation of the affected tissues. Thus, as a result of the manipulation of metal objects, such as jewelry accessories, watches, key rings, coins and mobile phones,episodes of allergic contact dermatitis may occur in predisposed individuals.
On the other hand, in case of ingestion, symptomatology is much more variable. This is found in many foods (plant and animal), the ingestion of which normally does not harm the health of the consumer.
In some cases, in people allergic to nickel, it can trigger the activation of the immune system. Symptoms related to ingestion may vary from subject to subject. In addition, it is hardly distinguishable from other forms of food allergies (nausea, abdominal swelling, headache, tiredness, itching, dermatitis).
So, if you suspect nickel allergy you can perform specifictests, skin (prick-test), or serological (RAST, etc.), that allow you to diagnose its real presence. People allergic to nickel should reduce the consumption of food that contains it and the time of exposure to metal objects.
Nickel allergy: what it is
This allergy consists of an adverse reaction of the body towards nickel,an element abundantly present in nature, food and everyday objects.
An allergic reaction is triggered by the activation of the immune system against the foreign substance (non-self), in this case represented by nickel. The immune response is cellulo-mediated, involving:
- lymphocytes T helper
- antibodies (IgE immunoglobulins)
- release of histamine
- pro-inflammatory molecules.
According to the triggering symptomatology, two main forms can be distinguished.
Contact Dermatitis (ACD). It may appear in paediatric age or arise in adulthood, after repeated or prolonged exposure to objects containing nickel, or after the first contact.
Systemic Nickel Allergy Syndrome (SNAS). This is an adverse reaction to food, of a non-toxic type, which occurs by ingestion and can occur at all ages.
Where is nickel located
Nickel is an element abundantly present on the earthy surface and lends itself well to industrial processing. Its uses are varied:
Nickel in objects
- Production of stainless steel
- kitchen utensils
- metal parts of glasses
- belts, etc.
But nickel can also be present in:
- hair dyes
- tattoo ink
- medical and surgical utensils (prostheses, needles, etc.).
It is a ubiquitous metal, present in soil, water and atmosphere in very variable concentrations and reaches the tables through the food chain. The plant and animal organisms that we consume take nickel from the soil, from water or, in turn, from their diet.
Furthermore, stored foods can absorb nickel from the tin or plastic packaging in which they are marketed (migration from the packaging).
In addition, preserved foods can absorb nickel from tin, or plastic, packaging in which they are marketed (migration from packaging).
Nickel allergy: nickel in food
Bearing in mind that the nickel content in food may vary depending on soil composition, the use of chemical fertilizers, local air pollution and many other factors, a distinction is made between the main consumer goods according to the nickel content (mg):
1- Low nickel foods: < 10 mg/100 g food
- drinking water (1)
- oranges (4,6)
- bananas (4)
- beer (2)
- broccoli (10)
- coffee (1)
- carrots (5)
- white flour (4)
- wholemeal rye flour (4)
- potato starch (3)
- strawberries (5,3)
- kiwi (4)
- lettuce (7.5)
- lemon (7)
- apples (1.2)
- sunflower oil (5)
- eggplant (1.3)
- corn oil (6)
- soybeans oil (6)
- olives (9)
- white potatoes without peel (4,8)
- grapefruit (6.5)
- salt (3)
- celery (2.9)
- spinach (7,2)
- wine (5)
- pumpkin (4)
- brown sugar (7)
- raw zucchini (4,4).
2 – Foods with a moderate nickel content: 10-100 mg/100 g of food
- apricots (12.5)
- pineapple (50)
- asparagus (15.5)
- wheat (29)
- oatmeal (96)
- fennel (34)
- raspberries (17)
- licorice (41)
- barley (53)
- peas (22)
- tomato (12.4)
- parsley (50)
- white rice (25)
- brown rice (37).
3 – High nickel content in food: > 100 mg/100 g food
- garlic (278)
- agar alga (200)
- peanuts (390)
- oats (230)
- cocoa powder (855)
- dark chocolate (223)
- cumin (280)
- dried figs (130)
- buckwheat (420)
- dried lentils (248)
- majorane (368), almonds (130)
- peppermint (340)
- Millet (199)
- hazelnuts (170)
- nuts (320)
- sunflower seeds (356)
- Oregano (953)
- pepper (687)
- sage (600)
- flaxseeds (223)
- soybeans (390)
- ginger (190).
Nickel allergy: symptoms
The main symptom of contact nickel allergy (ACD) is dermatitis, a skin outlet that manifests itself with itchy vesicles, redness and skin lesions similar to eczema.
Thus, we talk about localized dermatitis as symptomatology appears predominantly in the area where the contact took place. But, it can extend to other areas of the body. The manifestation of the allergic reaction can take a few hours (or days) and persist even for more than a week.
On the other hand, with regard to systemic ingestion syndrome (SNAS), symptomatology may be of different magnitudes.
- Cutaneous (diffuse dermatitis, urticaria, eczema, itching, lesions).
- Gastrointestinal (abdominal pain and swelling, nausea, diarrhea, vomiting, meteorism).
- Respiratory (allergic rhinitis and asthma).
- Neurological (headache, nervousness).
- Generalized (fever, fibromyalgia, joint pain, chronic fatigue).
Possible causes of nickel allergy
Nickel allergy can be inherited at birth (genetic inheritance).
What is inherited is actually a genetic predisposition to develop sensitivity to metal. Symptoms can manifest themselves in:
- pediatric age, or at a later time
- after triggers, such as prolonged exposure to objects containing nickel
- after excessive consumption of products stored in aluminum cans, etc.
But the individual can develop nickel allergy even in the absence of genetic predisposition. How is this done? The immune system is programmed to defend the organism from foreign bodies. Sometimes, it can make errors of assessment and act out of ‘excessive defence’.
Thus, nickel contained in everyday objects, or in food, can be recognized as foreign by the immune system and trigger the activation of lymphocytes and the release of histamine.
In addition, at a second contact the immune response will be stronger, by the action of memory lymphocytes.
To limit the likelihood of developing nickel allergy, itis recommended to limit exposure to objects containing this metal and consume freshfoods, grown without the use of pesticides.
Diagnosis of nickel allergy
Diagnosis of nickel allergy is not easy to perform, as symptomatology is common to other pathological conditions. The presence of familiarity, in addition to symptomatology, can be a clue that must be taken into account. However, to validate the actual presence of nickel allergy, specific tests should be performed.
Oral provocation test (TPO)
The oral provocation test (TPO) involves the direct administration of the allergen, in this case foods containing nickel. It must always be carried out under strict medical supervision, as it presents a high risk to the patient.
To reduce the likelihood of false positives,this test is usually performed in double-blind (DBPCFC), providing the patient with an allergy control substance (placebo), for which he will not have to manifest symptomatology.
Foods containing suspected allergen -in this case nickel – for a longer or longer period are removed from the patient’s diet. If during this period the symptomatology is reduced, it can be deduced that the patient has sensitivity towards the food, but it could be a simple intolerance.
Diagnostic tests (prick tests, RAST, etc.) are required for allergy diagnosis.
In vivo skin tests (skin prick test, patch test)
The execution of these tests provides that a small rate of allergen (nickel) is put in contact with the patient’s skin (usually forearm or back) directly (prick test), or with the help of allergen-soaked patches (pach test).
In the presence of nickel sensitivity,after 20-25 minutes, a local skin reaction (redness) will be observed in the contact area, similar in diameter to that generated by exposure to histamine (positive control test).
Otherwise, no reactions will be observed on the skin,similar to negative control (glycerol-saline solution). These tests are mainly used to diagnose contact dermatitis,but they can provide useful, but not diagnostic, indications, even in the case of suspected food allergy.
In vitro testing (RAST, ISAC)
The RAST test (Radio Allergo Sorbent Test) performs the search for specific food IgE antibodies in the serum (ELISA method). It provides quantitative measurement of antibodies and is performed in vitro. The RAST test indicates the presence in the subject of specific allergen IgE, but does not allow the clinical diagnosis of food allergy.
The less well-known ISAC test is an in vitro test based on the dosage of IgE on microarrays, which identifies individual sensitivity to 112 food allergens, including nickel. It is also carried out by blood sampling and reports a quantitative assessment.
Note: the only positivity to diagnostic tests, in the absence of symptomatology, identifies a genetic predisposition but is not an indication of manifest allergy.
Nickel allergy: how to cure
There is no definitive remedy to eliminate nickel allergy at its root, however it is possible to reduce its associated symptomatology.
For contact dermatitis there are drugs for skin use, or oral, based on corticosteroids (anti-inflammatories). For skin use, in the form of cream or ointment, to be applied on the contact area, for soothing purposes, or tablets, to be taken following exposure to nickel.
For systemic symptomatology, on the other hand, it is recommended to excludefoods containing nickelfrom their diet, paying attention to packaging and content in “traces”.
A widely used therapeutic approach is oral hyposensitizing treatment. This approach provides for a diet of exclusion of foods containing nickel even in small quantities,and then proceeds to a subsequent reintegration, gradual and controlled.
Many patients undergoing this therapy have shown a reduction in symptoms as a result of ingestion of foods containing nickel (hyposensitization). So they were able to resume a varied diet. It should be borne in mind that this therapeutic approach does not guarantee the effective disappearance of the allergy and depends on individual sensitivity (for some it may work, for others it does not).
It is strongly discouraged to try this method in the absence of medical indication, as food allergies are not to be underestimated.
Diet and example of nickel free menu
A nutritional intervention can be useful to modulate nickel-induced cellular damage, but it does not lead to the disappearance of the allergy. The immune response that triggers nickel in contact with the mucous membranes of the organism in allergic people, in fact, leads to the formation of free oxygen radicals (ROS), with damage to tissues (lipid peroxidation) and DNA.
The general characteristics of a diet for nickel-sensitive people are:
- low-nickel foods
- abundance of antioxidants capable of counteracting the action of free radicals
- adequate iron intake, necessary to minimize nickel absorption.
Nickel-free menu example (ca.1500 kcal)
- toast with 2 slices of wholemeal bread and cooked ham (20 g)
- 1 glass of orange juice, or grapefruit (200 ml).
- 1 apple (200 g).
- pasta (80g) with zucchini (200g) and grana (10g)
- 1 tablespoon extra virgin olive oil.
- 1 banana (200 g).
- rice (80 g), grilled chicken breast (200 g), radicchio (a pleasure)
- 1 tablespoon extra virgin olive oil.
Foods to avoid
- Foods with a high nickel content:bran, oats, buckwheat, soybeans, legumes (especially dried legumes, such as peas and dried beans), chocolate, cocoa, all kinds of dried fruits (especially nuts, hazelnuts and peanuts), licorice, some crustaceans and molluscs.
- Moderate nickel content: herring,mackerel, tuna, tomato, onion, carrot and some fruits, especially apples and pears. Cooking, however, increases the degree of tolerability for the organism.
- Canned vegetables orlegumes, as nickel is often used as a preservative.
- Foods rich in iron and vitamin C.
- Foods containing trace nickel: refined flour, dairy products, meat, potatoes, cooked carrots, rice, tea and coffee.
Why it gets fat with nickel allergy
People with nickel allergy, before diagnosis and subsequent exclusion of foods containing the allergen, show weight gain and have difficulty losing weight.
This also applies to other forms of food allergies. In fact, the activation of the immune system that takes place in the presence of the allergen triggers an inflammatory state at the level of the tissues.
This inflammation results in swelling and an increase in insulin levels in the blood,resulting in the accumulation of fat (lipogenesis).
In order to return to its weight in the presence of nickel allergy, it is necessary to eliminate foods for which sensitivity is present.
There are many foods containing nickel, therefore, to avoid incurring nutritional deficiencies,it is advisable to contact nutrition specialists able to draw up a complete dietary plan of the nutrients necessary for your daily needs.
More tips to avoid Nickel allergy
Attention should be paid to the use of nickel-free (nickel-free) cutlery and utensils, nickel-tested cosmetics (tested products for which nickel is found to be present in quantities less than 0.00001%) and avoid cigarette smoking,even passive, as each cigarette contains on average 1-3 μg of nickel.
The indication is always not to rely on DIY diets,but to follow the advice of a team of experts in nutrition and food allergies.