Impact of Restrictive Diets on Inflammation and Quality of Life in Autoimmune Thyroiditis (TAILOR)

November 1, 2026 updated by: Natalia Toro Funes, University of Barcelona

Impact of Restrictive Diets Targeting Inflammatory Dietary Components (Gluten, Casein, and High-glycemic-index Carbohydrates) on Inflammatory Markers and Quality of Life in Patients With Autoimmune Thyroiditis

The purpose of this clinical trial is to evaluate whether a dietary intervention can improve clinical and immunological outcomes in women with autoimmune thyroid disease (AITD), including Hashimoto's thyroiditis and Graves' disease. The study will enroll premenopausal women aged 18 to 55 years.

The dietary intervention consists of the simultaneous exclusion of three groups of potentially pro-inflammatory dietary components:

  • Gluten-containing cereals, including wheat, barley, and rye.
  • Casein, the main protein found in milk and dairy products.
  • High-glycemic-index carbohydrates, such as refined sugar, white bread, and white rice.

The primary objective is to determine whether the dietary intervention reduces serum levels of anti-thyroid peroxidase (anti-TPO) antibodies, which are markers of thyroid autoimmunity.

Secondary objectives include evaluating whether the intervention improves:

  • Fatigue and energy levels.
  • Mood and emotional well-being.
  • Gastrointestinal symptoms.
  • Health-related quality of life.

Women following the dietary intervention will be compared with women who continue their habitual diet to assess the effectiveness of the intervention. Group allocation will be based on participants' choice at study enrollment.

Participants will:

  • Follow either the dietary intervention or their usual diet for 12 months while continuing their prescribed medical treatment.
  • Attend four study visits: at baseline and after 4, 8, and 12 months.
  • Undergo anthropometric assessments (body weight and waist circumference), blood sampling, stool collection, and a telemedicine consultation with a thyroid specialist at each visit.
  • Complete brief online questionnaires every month to assess dietary adherence, fatigue, mood, gastrointestinal symptoms, and quality of life.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Background:

Previous studies have investigated the effects of gluten-free diets, casein-free diets, or the restriction of high-glycemic-index carbohydrates separately in individuals with autoimmune thyroid disease (AITD), yielding heterogeneous and inconclusive findings. The present study aims to evaluate the combined effect of simultaneously excluding these dietary components on immunological, clinical, and patient-reported outcomes in women with AITD. The dietary intervention is intended as a nutritional strategy under investigation and is not designed to replace standard medical treatment or routine clinical care.

Dietary Intervention:

Participants assigned to the intervention group will simultaneously eliminate gluten-containing cereals (wheat, barley, and rye), dairy-derived casein, and high-glycemic-index carbohydrates from the start of the study. No sequential elimination or reintroduction phases are planned. The study periods (months 0-4, 4-8, and 8-12) correspond exclusively to predefined assessment intervals. Apart from the dietary exclusions under investigation, participants will be advised to maintain a stable dietary pattern with comparable energy intake and macronutrient distribution throughout the study.

Group Allocation:

This is a prospective, non-randomized study. Group assignment will be determined at baseline, prior to initiation of the intervention, according to each participant's willingness and ability to follow the dietary protocol. To minimize potential selection bias associated with the absence of randomization, propensity score methods based on baseline characteristics, including age, body mass index (BMI), baseline anti-thyroid peroxidase antibody (anti-TPO) levels, thyroid-related treatment, and relevant lifestyle factors, will be incorporated into the statistical analysis through adjustment, stratification, or inverse probability of treatment weighting, as appropriate.

Adherence Assessment:

Adherence to the dietary protocol will be evaluated using a Nutritional Adherence Index calculated as: Adherence (%) = (days with complete compliance / total days evaluated) x 100. In the intervention group, satisfactory adherence will be defined as a compliance rate of at least 90%.

Sample Size Calculation:

The sample size is based on the primary outcome (change in anti-TPO antibody concentrations from baseline to month 12). In a comparable non-randomised trial of a gluten-free diet in women with Hashimoto's thyroiditis (Krysiak R, Szkróbka W, Okopień B. Exp Clin Endocrinol Diabetes. 2019;127(7):417-422. doi: 10.1055/a-0653-7108), the standard deviations of the 6-month change in anti-TPO were 105 and 25 U/mL (pooled SD approximately 74 U/mL), with a between-group difference of 229 U/mL. Assuming a pooled SD of 74 IU/mL, a two-sided alpha of 0.05 and 80% power, 24 evaluable participants per group allow detection of a between-group difference of about 60 IU/mL, approximately one quarter of the effect previously reported. Allowing for approximately 20% attrition, 30 participants per group will be recruited (total N = 60).

Statistical Analysis:

The primary analysis will evaluate changes in anti-TPO antibody concentrations between groups using multivariable regression models adjusted for potential confounding factors. Longitudinal changes across follow-up visits will be assessed using repeated-measures analysis of variance (ANOVA) or linear mixed-effects models, as appropriate. Both intention-to-treat and per-protocol analyses will be performed. Missing data will be addressed using multiple imputation methods.

Safety Monitoring:

Participants will be monitored throughout the study for potential adverse effects related to the dietary intervention. Predefined safety criteria include unintentional weight loss exceeding 5% of body weight within one month, clinically significant thyroid dysfunction requiring treatment adjustment, persistent gastrointestinal symptoms, evidence of nutritional deficiency, and significant psychological distress. Adverse events will be evaluated within 48 hours of notification, and serious adverse events will be reported to the relevant Ethics Committee within 7 calendar days, in accordance with applicable regulations.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
60

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 55 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

Female

Description

Inclusion Criteria:

  • Women aged 18 to 55 years, of reproductive age and not menopausal
  • Confirmed diagnosis of autoimmune thyroiditis (Hashimoto's thyroiditis or Graves' disease) based on clinical, hormonal and immunological criteria
  • Under clinical follow-up by an endocrinology unit
  • Stable thyroid function; if on pharmacological treatment, stable for at least 3 months before study entry
  • No relevant nutritional deficiencies (vitamin D, selenium, zinc, iron or vitamin B12), or adequately supplemented according to clinical criteria
  • Willingness to participate in a supervised nutritional program and signed informed consent

Exclusion Criteria:

  • Other active autoimmune or systemic diseases (e.g., lupus, multiple sclerosis, type 1 diabetes), active inflammatory bowel disease, peptic ulcer or intestinal infections
  • Established menopause or perimenopause
  • Body mass index outside the range 18.5-29.9 kg/m2
  • Pregnancy or breastfeeding
  • Use of immunosuppressive drugs or corticosteroids
  • Previous restrictive diets
  • Severe food intolerances or conditions preventing adherence to the protocol (e.g., wheat allergy, celiac disease, casein allergy)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Triple-restriction diet

Participants will follow a dietary protocol involving the simultaneous exclusion of gluten-containing cereals, dairy-derived casein, and high-glycemic-index carbohydrates from baseline through month 12. The intervention will be supported by individualized dietary guidance and monthly monitoring of adherence to the protocol.
Other: Gluten-free, casein-free, low-glycemic-index diet

Participants in the intervention group will follow a dietary protocol consisting of the simultaneous exclusion of gluten-containing cereals (including wheat, barley, rye, spelt, and foods containing gluten), dairy products containing casein (including milk, yogurt, cheese, cream, butter, and related products), and high-glycemic-index carbohydrates (including refined sugar, refined grain products, white rice, and pastries). The dietary intervention will be maintained continuously for 12 months. No investigational medications, mandatory dietary supplements, or other therapeutic interventions will be administered as part of the study protocol.
No Intervention: Usual diet

Participants in the control group will continue their habitual diet without prescribed dietary modifications or restrictions. Dietary intake will be monitored using food frequency questionnaires and monthly dietary records. Participants will undergo the same follow-up schedule, clinical assessments, biological sample collection, and patient-reported outcome evaluations as the intervention group over the 12-month study period.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change in serum anti-thyroid peroxidase (anti-TPO) antibody levels
Time Frame: Baseline (month 0) and month 12

Serum anti-TPO antibodies (IU/mL) measured by immunoassay in a fasting morning blood sample. Change from baseline to month 12 is compared between groups.
Baseline (month 0) and month 12

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change in serum anti-thyroglobulin (anti-Tg) antibody levels
Time Frame: Baseline, month 4, month 8 and month 12

Serum anti-Tg antibodies (IU/mL) measured by immunoassay.
Baseline, month 4, month 8 and month 12
Change in high-sensitivity C-reactive protein (hs-CRP)
Time Frame: Baseline, month 4, month 8 and month 12

Serum hs-CRP (mg/L) measured by immunoturbidimetry or nephelometry.
Baseline, month 4, month 8 and month 12
Change in erythrocyte sedimentation rate (ESR)
Time Frame: Baseline, month 4, month 8 and month 12

ESR (mm/h) measured by the Westergren method.
Baseline, month 4, month 8 and month 12
Change in fecal zonulin
Time Frame: Baseline, month 4, month 8 and month 12

Fecal zonulin measured by ELISA in a stool sample, as a marker of intestinal permeability.
Baseline, month 4, month 8 and month 12
Change in thyroid function (TSH, free T4 and free T3)
Time Frame: Baseline, month 4, month 8 and month 12

Serum TSH, free T4 and free T3 measured by immunoassay.
Baseline, month 4, month 8 and month 12
Change in micronutrient status (25-hydroxyvitamin D, ferritin and selenium)
Time Frame: Baseline, month 4, month 8 and month 12

Serum 25-hydroxyvitamin D, ferritin and selenium.
Baseline, month 4, month 8 and month 12
Change in fatigue (Fatigue Severity Scale)
Time Frame: Monthly from baseline to month 12

FSS: 9 items scored 1 to 7; total score is the mean of items (range 1-7). Higher scores indicate more fatigue.
Monthly from baseline to month 12
Change in anxiety and depression (Hospital Anxiety and Depression Scale)
Time Frame: Monthly from baseline to month 12

HADS: 14 items; anxiety and depression subscales each range 0-21. Higher scores indicate worse symptoms.
Monthly from baseline to month 12
Change in health-related quality of life (WHOQOL-BREF)
Time Frame: Monthly from baseline to month 12

WHOQOL-BREF: 26 items across physical, psychological, social and environmental domains. Higher scores indicate better quality of life.
Monthly from baseline to month 12
Change in gastrointestinal symptoms (Gastrointestinal Symptom Rating Scale)
Time Frame: Monthly from baseline to month 12

GSRS: 15 items scored 1 to 7 across 5 symptom dimensions. Higher scores indicate worse symptoms.
Monthly from baseline to month 12
Change in weight
Time Frame: Monthly from baseline to month 12

Weight (kg) measured with standard anthropometric techniques.
Monthly from baseline to month 12
Change in body mass index
Time Frame: Monthly from baseline to month 12

Weight and height, measured with standard anthropometric techniques, will be combined to report Body Mass Index in kg/m^2 .
Monthly from baseline to month 12
Change in waist circumference
Time Frame: Monthly from baseline to month 12

Waist circumference (cm) measured with standard anthropometric techniques.
Monthly from baseline to month 12
Dietary adherence (Nutritional Adherence Index)
Time Frame: Monthly from baseline to month 12

Percentage of days with full compliance with the assigned diet, calculated from monthly dietary records.
Monthly from baseline to month 12

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Barcelona

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Universidad Internacional de Valencia

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Laurence Lestang Doublet, MSc, RD, Universidad Internacional de Valencia
  • Principal Investigator: Natalia Toro Funes, PhD, Universidad de Barcelona
  • Study Director: Mariana Silva López, PhD, Universidad Internacional de Valencia

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
January 1, 2027

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 31, 2028

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2028

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
October 6, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 13, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 19, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
November 4, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 1, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
November 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • CEIDTDM2026_01

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data will not be shared. Data are pseudonymized during the study and irreversibly anonymized after publication; results will be reported in aggregate form only, in accordance with the informed consent and applicable data protection regulations (GDPR and Andorran Law 29/2021).

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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