NCT07481240

A Household-Based Dietary Intervention Study of Vitamin D Fortified Bread in Irish Families

Fam-D-Bread: A Household-Based Dietary Intervention Study of Vitamin D Fortified Bread in Irish Families

• Status: Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 390 (estimated)
• Sponsor: University College Cork · Academic / Other
• Sex: All
• Age: 5 Years – 59 Years
• Healthy volunteers: Accepted

Summary

Vitamin D deficiency is common. It is caused by limited sun availability together with a low supply of vitamin D in the food system. There is a high prevalence of low vitamin D status around the world. In Ireland, our relatively northern latitude and prevailing weather mean that UVB availability for skin synthesis of vitamin D is limited in this country and our population relies on the dietary supply of vitamin D to prevent deficiency. Thus, the endemic Irish problem of vitamin D malnutrition is due to the lack of vitamin D in our food system. Dietary guidelines cannot address this issue because foods naturally rich in vitamin D are very few and infrequently consumed. The FamDBread study will test the hypothesis that a vitamin D-fortified bread as part of a healthy diet that includes vitamin D-fortified foods is effective in preventing low vitamin D status during winter, and safe for families to consume.

Detailed description

This randomised controlled dietary intervention study aims to recruit households/families of children, teens and adults, with 390 participants who will be randomised to receive vitamin D-fortified bread and advice to consume additional commercially available fortified foods (Treatment group) or identical unfortified bread and advice to consume additional commercially available fortified foods (Control group). The outcome of the study is to test whether increasing vitamin D intake through food (Treatment group) is sufficient to prevent wintertime vitamin D deficiency (measured using serum concentrations of 25-hydroxyvitamin D \<30 nmol/L) in comparison with the Control group. The target vitamin D intake for the treatment group in this study is \>20 μg/ day vitamin D. This will maintain serum concentrations of 25-hydroxyvitamin D (25(OH)D) (the biomarker of vitamin D status) \> 30 nmol/L, the clinical deficiency threshold to prevent metabolic bone disease, in over 90% of participants. At this vitamin D intake level, about 80% of participants will have a 25(OH)D concentration \> 50 nmol/L, the personal intake target in the US and EU.

Conditions

• Vitamin D Deficiency

Interventions

Type	Name	Description
OTHER	Fortified Bread	Intervention group will be supplied with fortified bread delivering \>20 μg vitamin D3 in a daily portion and will receive dietary advice to incorporate fortified foods that are commonly available on the market in their diet.
OTHER	Unfortified bread	Placebo control group will be supplied with unfortified bread and will receive dietary advice to incorporate fortified foods that are commonly available on the market in their diet.

Timeline

• Start date: 2025-11-17
• Primary completion: 2026-03-31
• Completion: 2026-03-31
• First posted: 2026-03-18
• Last updated: 2026-03-18

Locations

2 sites across 1 country: Ireland