Irritable bowel syndrome (IBS) is a fairly common disorder characterized by stomach pain, diarrhea, constipation, gas, and bloating. Most people with these symptoms see a gastroenterologist for diagnosis and treatment. However, an allergy may actually be the culprit for those symptoms — and not all gastroenterologists are familiar with it yet. Systemic Nickel Allergy Syndrome (SNAS) is an allergic reaction to nickel that is in many food items, with the same symptoms as IBS. Nickel allergies can also result from touching nickel-based material, leading to allergic contact dermatitis of the skin (which is more commonly diagnosed). Nickel allergy is fairly common worldwide, especially in Asia and North America, but the symptoms may include either skin or stomach problems, or both.
Nickel is in our environment, including our soil and water, so it’s present in fruits, vegetables, animals, and us. Levels vary depending on the location, fertilizer and pesticide use, industrial contaminants, and other factors. Some metals contain nickel as well. Thus, treating a nickel allergy is difficult. For those with SNAS, adopting a nickel-free diet is challenging and many people cannot eliminate all foods that are high in nickel (see this list). However, some may find relief by reducing the amount of nickel ingested. Some chemicals, such as EDTA, ascorbic acid, citric acid, pectin, and tannins affect how nickel is absorbed. Iron and vitamin C supplementation can decrease nickel levels. Desensitization — where small amounts are given orally over time — may also treat SNAS. More education about SNAS and how it may appear like IBS is critical to develop proper treatment protocols. More research on this common allergy is needed to determine the best methods for treatment.
If you are an IBS patient who has not had improvement with typical treatment options, or if you have gastrointestinal reactions to particular foods that are not normal triggers for IBS, consider asking your doctor about SNAS. A skin-patch allergy test can usually quickly show if you have a nickel allergy.
Some resources: Medscape review, 2021 publication on SNAS