Nickel is a silver-white metal found naturally in the environment. It’s commonly used with other metals in items like jewelry, braces, coins and keys. Few people know, however, that nickel can also be found in many everyday foods. While most people tolerate nickel with no issues, it can cause an immune response in some people. Today, we’re going to delve into everything you need to know about nickel allergy—what it is, what symptoms to look for, and how to treat it.
Symptoms of a nickel allergy
There are a couple of different types of allergic reactions to nickel. One is called allergic contact dermatitis (ACD) in which exposure to a substance on the skin surface (in this case, nickel) can trigger a rash at the site of skin contact.
A related type of allergic reaction is called systemic contact dermatitis (SCD) in which a person who is already sensitized to a substance through skin contact is exposed to that substance (allergen) via a systemic route (i.e. through food). For example, people allergic to nickel in jewelry may sometimes also develop a rash after eating foods that contain nickel. In systemic contact dermatitis caused by nickel, eating high-nickel foods may trigger different types of rashes. The classic manifestation is a blistering rash on the hands. Other types of skin reactions include all-over dermatitis, itchy bumps on the elbows, hives, eczema and itching.
In others, a third type of reaction goes beyond skin irritation to include symptoms like headaches, migraines, asthma, irritable bowel syndrome, joint swelling and pain, colitis, stomachache and tinnitus. The presence of wide-spread systemic symptoms triggered by nickel is referred to as Systemic Nickel Allergy Syndrome (SNAS).
Diagnosing nickel allergy
Contact allergy to nickel is diagnosed by a patch test. Patch testing involves applying a patch containing the test substance (in this case, nickel) to a person’s back. Because the reaction takes two or three days to become visible, the patch is left in place for up to 72 hours. Based on the skin’s response to the patch, a nickel allergy is either confirmed or ruled out.
Unlike contact allergy to nickel, there is no way to definitively diagnose Systemic Nickel Allergy
Syndrome (SNAS). This type of sensitivity is often experienced with conditions like fibromyalgia, chronic fatigue, and other chronic conditions, so Systemic Nickel Allergy Syndrome is often difficult to diagnose. A diagnosis is typically made based on symptoms or an elimination diet.
Alleviating the symptoms of a nickel allergy
People suffering from allergic contact dermatitis can often rid of their symptoms simply by avoiding external contact with nickel, such as in jewelry, coins, and other metal items. In other people, however, especially those with systemic contact dermatitis or Systemic Nickel Allergy Syndrome, a low-nickel diet may be required to clear their symptoms.
Foods to avoid on a low-nickel diet
The level of nickel in foods depends on the plant species and the nickel content of the soil. In the case of seafood, the content depends on the aquatic environment. While the levels of nickel in foods aren’t concrete, certain foods are known to contain more nickel than others. Here are few high-nickel foods to avoid, as well as ones that are safe to consume, while on a low-nickel diet.
Avoid: Whole wheat foods and oats
May eat: Rice, corn, rye
Avoid: Beans, lentils, peas, soybeans, spinach, kale, lettuce, canned vegetables, vegetable juices
May eat: Other fresh or frozen vegetables
Avoid: Dates, figs, pineapples, plums, raspberries, canned fruits
May eat: Other fresh or frozen fruits
Avoid: Shellfish, processed meats with coatings or fillers, canned meats or fish
May eat: Beef, chicken, fish, turkey, eggs
Other sources to avoid
Chocolate, cocoa powder, all nuts (especially cashews), all seeds, all sources of soy (soy sauce, soybeans, tofu, etc.), black tea, all canned products, commercial salad dressings, multivitamins that contain nickel.
Please note that the above list is not exhaustive. To view a more comprehensive list, click here. You will have to avoid these foods for at least six weeks to see if this will make a difference in your symptoms. During this time, you should also continue to avoid objects that may potentially contain nickel.
The bottom line
If a low-nickel diet resolves your symptoms, you can introduce foods one by one (one per week) to see how you react to them. Some people don’t react to all the foods listed above, only some of them. By slowly adding the foods back in, you can pinpoint which ones are your personal triggers. It’s also helpful to eat foods rich in iron and take vitamin C with every meal, as these counteract the absorption of nickel.
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