Vitamin D (Bio)Fortified Shopping Baskets to Improve Vitamin D Status

May 5, 2026 updated by: University of Ulster

Vitamin D (Bio)Fortified Shopping Baskets to Improve Vitamin D Status: a Household-level RCT

Vitamin D is essential for healthy bones, muscles, and immune function. It comes from food, supplements, and sunlight. There are two main forms; vitamin D2, found mainly in plant foods, and vitamin D3, which comes from animal foods and is more effective at increasing vitamin D levels in the body. In the UK, sunlight is often too weak especially in winter for the body to make enough vitamin D, so people rely mainly on dietary sources and supplements. Despite this, many people in the UK have low vitamin D levels, and teenagers are particularly at risk due to increased needs during growth, with around one in five adolescents having low vitamin D levels. Poor intake of vitamin D-rich foods, low supplement use, and inconsistent food fortification contribute to this problem. This study aims to assess whether a family-based household diet using natural and fortified vitamin D foods during winter can improve vitamin D levels in adolescents.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Enrolling by invitation

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

Vitamin D is important for keeping bones, muscles, and the immune system healthy. There are two main types of vitamin D; vitamin D2, which mainly comes from plant-based foods, and vitamin D3, which mostly comes from animal foods and sunlight. Vitamin D3 is better at raising vitamin D levels in the body. After vitamin D is consumed or made in the skin, it is processed by the liver and kidneys into an active form that the body can use. People get vitamin D from food, supplements, and sunlight. Natural food sources include oily fish, meat, eggs, and liver. Some foods, such as breakfast cereals, spreads, and yoghurts, have vitamin D added to them (fortified foods). A small number of foods, like certain mushrooms, eggs, and bread, are also biofortified to contain higher levels of vitamin D. However, in countries like the UK, sunlight is often not strong enough especially in winter to allow the body to make enough vitamin D, so people rely more on food and supplements. Vitamin D levels are measured using a blood test. In the UK, a large proportion of the population has low vitamin D levels, with many people being either deficient or insufficient. Low vitamin D increases the risk of weak bones and bone diseases, such as rickets in children and osteoporosis in adults. Teenagers are especially at risk because their bodies need more vitamin D during periods of rapid growth. National surveys show that nearly one in five adolescents in the UK has low vitamin D levels, particularly during winter. Low intake of vitamin D-rich foods, limited supplement use, and reduced sunlight exposure all contribute to this problem. Although some foods in the UK are fortified with vitamin D, fortification is voluntary, meaning vitamin D levels vary widely between products. This makes it difficult for families to meet their vitamin D needs through diet alone. While studies have shown that vitamin D fortification can improve vitamin D levels, most research has focused on single foods rather than looking at the whole family diet. There is limited evidence on whether using a range of vitamin D-rich and fortified foods at home can help improve vitamin D levels in adolescents. This study aims to assess whether a family-based, household-level dietary intervention using natural and fortified vitamin D foods during winter can improve vitamin D status in families with adolescents.

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.
160

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 Locations

  • United Kingdom
      • Coleraine, United Kingdom, BT52 1SA
        • Ulster University, Human Intervention Studies Unit, Coleraine, Co. Londonderry

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

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Households with at least one adult member (≥18 years) and at least one adolescent member (11-17 years).
  • Participants willing to consume the majority of study foods provided
  • Participants willing to provide a total of two blood samples (maximum 25ml at each timepoint).

Exclusion Criteria:

  • Any food allergies or intolerances, including anaphylaxis allergies
  • Individuals taking/unwilling to stop taking high dose vitamin D supplements (1000 IU) for a washout period (4 weeks before) and for the duration of the study period
  • Other major dietary exclusions, e.g. those following vegan or vegetarian lifestyles.
  • Individuals with conditions causing malabsorption, e.g. coeliac disease

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: Other
  • Allocation: 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: Vitamin D (bio)fortified foods
Other: Vitamin D (bio)fortified food basket
Basket of vitamin D (bio)fortified foods provided to a household for consumption
Experimental: Control foods
Other: Control food basket
Basket of control foods provided to a household for consumption

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
Vitamin D status
Time Frame: From enrolment to the end of treatment at 4 weeks, comparison between treatments
Measured by LC-MS/MS for 25(OH)D concentrations (µmol/L)
From enrolment to the end of treatment at 4 weeks, comparison between treatments

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
Acceptability of food baskets
Time Frame: From enrolment to the end of treatment at 4 weeks, comparison between treatments
Measured by qualitative interview to assess acceptability of food baskets provided to households
From enrolment to the end of treatment at 4 weeks, comparison between treatments
Perceptions and habits of vitamin D
Time Frame: From enrolment to the end of treatment at 4 weeks, comparison between treatments
Measured by quantitative and qualitative (open ended questions) questionnaire to assess perception and habits of vitamin D
From enrolment to the end of treatment at 4 weeks, comparison between treatments
Vitamin D intake
Time Frame: From enrolment to the end of treatment at 4 weeks, comparison between treatments
Measured by validated Food Frequency Questionnaire, reported as average vitamin D intake µg/day.
From enrolment to the end of treatment at 4 weeks, comparison between treatments
Knowledge of vitamin D
Time Frame: From enrolment to the end of treatment at 4 weeks, comparison between treatments
Measured by quantitative (percentage score between 0% and 100%, higher score indicating better knowledge) and qualitative (open ended questions) questionnaire to assess knowledge of vitamin D
From enrolment to the end of treatment at 4 weeks, comparison between treatments

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 Ulster

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.
Agri-Food and Biosciences Institute
Foodovation North West Regional College
Kenedy Bacon
Sofina Foods Europe
Humanativ Ltd

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 (Actual)

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.
February 12, 2026

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.
April 1, 2027

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.
April 1, 2027

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).
January 8, 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.
January 8, 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.
January 16, 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.
May 6, 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.
May 5, 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.
January 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.
  • REC/24/0076

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

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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