Approximately 200 families corresponding to 800 persons are included in the study. The study investigate the efficacy of vitamin D fortification of bread and milk on vitamin D status in serum. Participants receive milk and bread twice a week. Half of the participants receive vitamin D fortified products and the other half similar non-fortified products. The study starts in September and runs for 6 months during winter, the period where it is not possible to produce vitamin D in the skin through sunlight exposure. The hypothesis is that the usual fall in vitamin D status can be prevented by vitamin D fortified food.

Inclusion Criteria:

• Family with at least one child between the age 4 to 18 years and at least one adult less than 60 years of age
• Permanent address in a specific geographical region.

Exclusion Criteria:

• Use of medication (including dietary supplements with high levels of vitamin D)
• Diseases which influence vitamin D metabolism
• Pregnancy