This was a single-center, open-label, single-arm, exploratory self-controlled study evaluating NatureU Histra Disslove in adults with chronic urticaria symptoms. Twenty-four participants were screened, 19 participants were enrolled, and 19 participants completed the study and were included in the effectiveness analysis. Participants took one tablet of the study product orally once daily, 20 minutes before a main meal, for 28 consecutive days. Urticaria Control Test, Urticaria Activity Score 7, and Dermatology Life Quality Index assessments were performed at baseline, Day 14, and Day 28. Safety was monitored during the study.

The study was designed as an exploratory human evaluation of a food product containing active diamine oxidase (DAO). Screening was conducted from August 29, 2024 through October 4, 2024. After investigator review of the inclusion and exclusion criteria, 19 adults with chronic urticaria symptoms were enrolled on October 4, 2024. Participants received NatureU Histra Disslove at the study center on Day 0 and took the product continuously for 28 days through Day 28. The protocol specified oral intake of one tablet 20 minutes before a main meal, preferably dinner. Outcome assessments included the Urticaria Control Test (UCT), Urticaria Activity Score 7 (UAS7), and Dermatology Life Quality Index (DLQI) at Day 0, Day 14, and Day 28. Safety monitoring included adverse event collection and laboratory safety assessment. The study was open-label, single-arm, and self-controlled, with no placebo or parallel control group. Analyses were based on participants who completed the study assessments.

Inclusion Criteria:

1. Participants who signed informed consent before the study and understood the study content, procedures, and possible adverse reactions.
2. Adults diagnosed with chronic urticaria by a dermatologist based on clinical symptoms and medical history.
3. Age 18 to 65 years.
4. Participants with typical wheals with itching and/or angioedema symptoms of chronic urticaria and either a Urticaria Activity Score 7 of at least 7 or a Urticaria Control Test score below 12.
5. Participants willing to maintain normal healthy routines during the study, avoid alcohol, and avoid foods likely to trigger allergic reactions.

Exclusion Criteria:

1. Severe internal organ disease, including heart disease, kidney disease, or other serious disease that could affect product metabolism.
2. Known allergy or intolerance to any ingredient of the study product.
3. Other skin disease or systemic disease that could affect urticaria manifestations.
4. Participation in another clinical trial or use of prohibited drug treatment.
5. Heavy smoking, alcohol abuse, or other lifestyle factors that could affect study results.
6. Severe psychological disorder or cognitive impairment that could affect compliance.
7. Inability to follow study dietary restrictions or requirements because of religious or personal reasons.
8. Abnormal blood routine, liver function, kidney function, or other laboratory test results outside the normal range.
9. Population for whom the product was contraindicated, including minors, participants planning pregnancy, pregnant or lactating participants, participants with liver or kidney disease history, and participants taking long-term medication.
10. Any other factor judged by the investigator to make participation inappropriate.

The study was open-label with no masking.