Pectin Intervention Study and Long-term Follow-up in Lipid Transfer Proteins Allergic Patients

Pectins are dietary fibers that have shown a health effect on patients with food allergy, as they are capable of modifying the composition of gastrointestinal microbiota, and producing an immunomodulatory effect. Preliminary results by the investigators show that the intervention for 2 months with pectins produces an increase in tolerance to peach, and changes in the microbiota compared to the group of patients treated with placebo. In this project, the investigators aim to study these clinical effects and the involved mechanisms. Moreover, the long-term effect (clinical reactivity to nsLTP and immunomodulatory effect) of the dietary intervention will be prospectively evaluated 6 months after the intervention.

Patients of 3 different Allergy Units with clinical history of allergic reactions with peach and with/without reactions with peanut due to sensitization to nsLTP will be informed about the intervention study and potential risks. After obtention of written informed consent, screening phase evaluation will be performed (skin prick tests (SPT), obtention of blood and feces samples and double-blind placebo-controlled food challenges (DBPCFC) with peach and peanut). Participants who meet the eligibility requirements will be randomized in a ratio 1:1 to pectin (apple pectin 10 mg + maltodextrin 5 mg; once daily) or placebo (maltodextrin 5 mg; once daily). The dietary intervention will last 6 months and a follow-up visit in month 3 will be performed. After completing the dietary intervention all participants will be clinically assessed (SPT and DBPCFC) and new blood and feces samples will be collected. Finally, patients who receive the active will be clinically evaluated with DBPCFC to peach and peanut after 6 months of completing the dietary intervention. Also, new blood and feces samples will be obtained.

The main objective is to analyze the clinical efficacy of a pectin dietary supplement administered once a day for 6 months as a treatment for nsLTP allergy in a randomized double-blind placebo-controlled multicenter intervention study. In addition, the investigators will study changes in clinical reactivity to nsLTP and the immunomodulatory effect (immunological humoral and cellular, metabolomics and microbiota profiles). Furthermore, long-term effects of the dietary intervention will be analyzed in participants from the active group (pectin) 6 months after completing the intervention.

Eligibility Criteria:
Inclusion Criteria:

* Adults with a clear clinical history of food allergy after eating peach (oral allergy syndrome and/or systemic symptoms) and with or without clinical history of food allergy with peanut.
* Sensitization to Pru p 3 by positive skin prick test (SPT wheal area \>7 mm2) and specific IgE (sIgE \>0.35 kUA/L)
* Positive DBPCFC with peach juice.
* If clinical history of food allergy with peanut, sensitization must be confirmed by positive SPT to peanut and sIgE \>0.35 kUA/L to Ara h 9 and clinical reactivity through a positive DBPCFC with peanut.
* Signed informed consent.

Exclusion Criteria:

* Food allergy to corn.
* Food allergy to peanut due to sensitization to storage proteins.
* Previous/active treatment with sublingual immunotherapy to Pru p 3.
* Pregnancy/lactation.
* Active infections.
* Inflammatory, autoimmune, and/or oncological diseases.
* Severe immunodeficiency.
* Metabolic syndrome.
* Increased liver parameters and/or any liver disease.
* Alcohol disorder.
* Mental illness.
* Mast cell activation syndrome.
* Severe atopic dermatitis.
* FEV1 \< 70%
* Treatment with immunomodulators in the last five years.
* Vitamin supplements, probiotics, prebiotics, antibiotics, metformin, statins, proton pump inhibitors, or corticosteroids in the last three months.
* Any clinical condition contraindicating performance of DBPCFC.