Effect of Vitamin C on Allergy Skin Test

Sponsor

National University of Malaysia (Other)

Overall Status

Not yet recruiting

CT.gov ID

NCT05810233

Collaborator

(none)

Enrollment

Arms

Anticipated Duration (Months)

Study Details

Study Description

Brief Summary

This study will assess the effect of taking vitamin C on allergy skin test.

Condition or Disease	Intervention/Treatment	Phase
Rhinitis, Allergic Allergy	Dietary Supplement: Ascorbic acid 1000mg	N/A

Detailed Description

Allergic rhinitis (AR) is an Immunoglobulin E (IgE) mediated inflammation of the nasal cavity. House dust mite is the most common causative allergen. The skin prick test is the preferred method to confirm allergy. This test is interpreted by measuring the skin wheal reaction in response to allergen application and histamine. Prior studies have shown that Vitamin C may have antihistamine effect that may reduce the wheal reaction in skin prick test thus cause difficulties to interpret the results. Current guidelines do not recommend cessation of vitamin C prior to skin prick test. This will require further study in order to further understand the effect of vitamin C in commercially available dose on the skin prick test wheal reaction. In this randomized placebo controlled trial, consecutive participant visiting the ENT clinic with allergic rhinitis and prior positive skin prick test towards dust mite will be screened for inclusion and exclusion criteria. Participants will either receive vitamin C 1000mg daily for 7 days or placebo. The skin prick test will be performed after one week of intervention and the area of the wheal reaction area (mm2) and longest diameter (mm) recorded. This will be compared between the two groups. The expected outcome is that participants with oral supplementation of vitamin C will have reduced SPT wheal reaction compared to placebo group.

Study Design

Study Type:

Interventional

Anticipated Enrollment :

90 participants

Allocation:

Randomized

Intervention Model:

Single Group Assignment

Masking:

Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)

Primary Purpose:

Diagnostic

Official Title:

The Effect of Vitamin C on the Skin Prick Test Wheal Reaction

Anticipated Study Start Date :

May 1, 2023

Anticipated Primary Completion Date :

Sep 30, 2023

Anticipated Study Completion Date :

Oct 30, 2023

Arms and Interventions

Arm	Intervention/Treatment
Experimental: Vitamin C Commercially available Tablet Vitamin C 1000mg per day for 7 days	Dietary Supplement: Ascorbic acid 1000mg Health supplement Other Names: VItamin C
Placebo Comparator: Placebo Sucrose tablets 1 per day	Dietary Supplement: Ascorbic acid 1000mg Health supplement Other Names: VItamin C

Arm

Intervention/Treatment

Experimental: Vitamin C

Commercially available Tablet Vitamin C 1000mg per day for 7 days

Dietary Supplement: Ascorbic acid 1000mg

Health supplement

Other Names:

VItamin C

Placebo Comparator: Placebo

Sucrose tablets 1 per day

Dietary Supplement: Ascorbic acid 1000mg

Health supplement

Other Names:

VItamin C

Outcome Measures

Primary Outcome Measures

Skin prick test wheal area of vitamin C group compared to placebo [Day 8]
Skin wheal reaction is measured using computer software. Day 8 wheal area of vitamin C group compared to placebo.

Secondary Outcome Measures

Skin prick test wheal reaction at day 8 of intevention compraed to prior skin prick test done as standard of care [Day 8]
Skin wheal reaction are is measured from prior skin test record (baseline) and at day 8 skin test repeated and measured. Area at day 7 - baseline.

Eligibility Criteria

Criteria

Ages Eligible for Study:

18 Years to 40 Years

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

Inclusion Criteria:

Participants above 18-years old 2) Participants with history at least 2 symptoms of rhinitis triggered by dust 3) Positive SPT to Dermatophagoides pteronyssinus with wheal reaction of at least 5 mm done within the past 1 year.

Exclusion Criteria:

Prior skin prick test result form do not include a tracing of the wheal reaction.
Prior skin prick test was not performed in HCTM.
Participants who are actively smoking or who have smoked cigarette or vape in the past 6 months
Participants with skin conditions affecting the volar aspects of the arm.
Participants on beta-blockers
Participants contraindicated for skin prick test (pregnancy, history of anaphylaxis, poorly controlled asthma)
Participants on long term supplements (multivitamin, traditional supplement)
Participants contraindicated for vitamin c (vitamin c allergy, kidney dysfunction, history of kidney or bladder stones, hyperuricemia, thalassemia, G6PD deficiency, sickle cell disease, hamatochromatosis)
Participants at risk of vitamin C deficiency (hyperthyroidism, elderly, beastfeeding, diarrhoea, restricted diet secondary to inflammatory bowel disease, anorexia or cancer)