Inclusion Criteria:

1. Provide written informed consent if over 16 years; informed parental consent for children under-16 years, plus age-appropriate assent for children under-16 years.
2. Be a household with at least one adult ≥18 years, with at least one dependent aged 5 years or older.
3. Willing to consume bread provided and have storage capacity for frozen bread.
4. Be in good general health.
5. Be willing to follow the assigned diet for 8 weeks and attend the required appointments.

Exclusion Criteria:

1. Daily consumption of a vitamin D supplement with a dose exceeding >10µg/d (400 IU) equivalent.
2. Exposure to factors that may influence vitamin D status, such as winter sun holiday, ski holiday, tanning beds etc.
3. Are following a medically prescribed diet.
4. Have a diagnosis of a medical condition that may interfere with vitamin D absorption, such as Coeliac disease, Inflammatory Bowel Disease, cystic fibrosis, or metabolism, such as liver disease, renal disease.
5. Have a history of active cancer or a diagnosis of cancer within the past 5 years.
6. Have an allergy to the bread ingredients.
7. Are participating in another research study with an intervention or other lifestyle programme that would interfere with the outcomes of the study.
8. Are unable to read, write, or understand English.