Some patients affected by nickel-contact allergy present digestive symptoms in 
addition to systemic cutaneous manifestations, falling under the condition known 
as systemic nickel allergy syndrome (SNAS). A nickel-related pro-inflammatory 
status has been documented at intestinal mucosal level. The aim of the present 
study is to evaluate the prevalence of lactose intolerance in patients affected 
by SNAS compared to a healthy population. Consecutive patients affected by SNAS 
referring to our departments were enrolled. The control population consisted of 
healthy subjects without gastrointestinal symptoms. All subjects enrolled 
underwent lactose breath test under standard conditions. One hundred and 
seventy-eight SNAS patients and 60 healthy controls were enrolled. Positivity of 
lactose breath test occurred in 74.7% of the SNAS group compared to 6.6% of the 
control group. Lactose intolerance is highly prevalent in our series of patients 
affected by SNAS. Based on our preliminary results, we can hypothesize that in 
SNAS patients, the nickel-induced pro-inflammatory status could temporarily 
impair the brush border enzymatic functions, resulting in hypolactasia. Further 
trials evaluating the effect of a nickel-low diet regimen on lactase activity, 
histological features and immunological pattern are needed.