Metal Allergy Newsletter: One in a Million?
I've been really interested in this question - how many people have a systemic nickel allergy?
It is estimated that around 10% of the general population has a nickel allergy. The latest estimate that I have encountered on how many of those people have a systemic nickel allergy (meaning they react to nickel in food) comes from the text book, Metal Allergy: From Dermatitis to Implant and Device Failure, published in 2018. The chapter on systemic nickel allergy syndrome states that it is "thought to affect approximately 20% of ACD (allergic contact dermatitis to nickel) patients." Another chapter states that "around 40% of patients with a positive patch test to nickel and suspected reaction to dietary nickel will improve when placed on a low nickel diet." I believe with the trend in plant-based eating these numbers are likely true.
If we are being conservative with the numbers, let's say that 10% of the general population suffers from a nickel allergy. There are 7.9 billion people in this world, so that is 790,000,000 people with allergic contact dermatitis to nickel. If only 10% of those people are sensitive to dietary nickel, that is 79,000,000 people. Out of 1 million people that means there could be 10,000 of us.
Systemic Nickel Allergy Syndrome: Epidemiological Data from Four Italian Allergy Units (2014)
D.L. Ricciardi, A. Arena, E. Arena, M. Zambito, A. Ingrassia, G. Valenti, G. Loschiavo, A. D’Angelo &S. Saitta
The researchers in this article discuss how, to their knowledge, no study has looked at the prevalence of systemic nickel allergy syndrome (SNAS). This is the first study to address the issue of estimating SNAS incidence.
They define SNAS as the development of cutaneous (skin) and extracutaneous (outside of the skin) symptoms correlating to the ingestion of nickel from the diet. Symptoms associated with SNAS are occupational rhinitis, asthma, urticaria, angioedema, recurrent aphthosis (mouth ulcers), abdominal bloating and pain, diarrhea, constipation, nausea, vomiting, chronic gastroduodenitis (diagnosed by endoscopy), headaches, chronic fatigue, post-prandial dyspnea, cystitis and or vulvovaginitis, acne and iron deficiency anemia.
This study looked at 1696 patients in four allergy units in Sicily. SNAS was confirmed in 98 of those patients (5.78%). The researchers mention the most common symptoms associated with SNAS are cutaneous & gastrointestinal. They noted that 16.3% presented with IgE-mediated food allergy, “therefore suggesting underlying cross facilitating pathways.” The researchers also outline the correct approach to diagnose SNAS.
Although nickel content in food varies widely, a number of foods are recognized as being particularly rich. They list peanuts, beans, lentils, peas, soybeans, oats, cocoa, chocolate, nuts, whole wheat, pears and mushrooms.
In conclusion, their data supports the role of nickel-containing food as potentially responsible for cutaneous (skin) and extracutaneous symptoms (symptoms other than skin) in nickel sensitized patients.
Diagnosing a Systemic Nickel Allergy
This week's research article highlighted an approach to diagnose SNAS that I want to share. A lot of us are self-diagnosed, hopefully we can change this by raising awareness. Sharing research articles with your clinicians is a great way to do this.
Positive patch test to nickel. You can also be diagnosed through a blood test. Visit melisa.org or orthopedicanalysis.com for more information.
Trial a low nickel diet for at least 1 month.
If symptoms improve on a low nickel diet, perform an oral challenge or 'provocation test'.
If symptoms return after and oral challenge (positive oral provocation test), SNAS is suspected.
Recipe of the Week: Swiss Chard Risotto
1 bunch of Swiss chard
1 cup of arborio rice
3.5 cups of broth of your choice
2 -3 tablespoons of butter
1/4 cup of chopped shallots
1/3 cup freshly grated parmesan cheese or fresh mozzarella if you have a histamine intolerance
Warm broth in a pot on the stove.
In a separate pan, sauté Swiss chard with butter until soft, add salt to taste and remove from pan.
Add butter and chopped shallots, cook until tender, about 3-4 min. Stir in rice and cook until rice starts to lightly brown, about 5 mins.
Add warm broth 1/2 cup at a time, stirring until evaporated. Continue adding 1/2 cup at a time until all liquid is absorbed (20min).
Stir in Swiss chard & cheese. Enjoy!
If you need help managing a systemic metal allergy book a free consult with me! If you are interested in enrolling for the Nickel Allergy Course, click >>HERE<<.