The study is a parallel interventional randomized dose-response trial designed to improve vitamin D intakes through food in a group of healthy 2 - 7.9 year old children. Subjects will be recruited from the general population in the greater Montreal area. The study will be conducted at the Mary Emily Clinical Nutrition Research Unit of McGill University. Children will be required to attend two study visits. Some information will be collected through monthly telephone survey to the parents. The investigators will add vitamin D to cheese and yogurt for daily consumption at home over a three month period. All products will be provided to the parents in the form of coded containers that do not contain any labels aside from the group and expiration date. Ingredient lists will be provided upon consenting to the study. To better understand vitamin D status; dietary intake, hematology, serum biochemistry including 25(OH)D, growth, and body composition will be measured at the beginning and end of the three month study period. In addition, bone mass at baseline will be assessed. Sun exposure will be documented and a skin pigmentation test will be used to more objectively assess chronic sun exposure. The investigators will also investigate the association between vitamin D intake and status with immune function.

Inclusion Criteria:

• Children will be pre-pubertal
• Healthy
• Regularly consume milk and milk products
• Healthy weights

All races will be studied.

Exclusion Criteria:

• Chronic diseases (including asthma) or medications known to affect vitamin D, infections or the immune system; known anaemia, small size at birth or preterm birth <37 wk gestation
• No milk allergy or lactose intolerance, no nutritional supplements Less than 1/3rd of preschool age children take a supplement based on our work; it will thus not be a limitation for recruitment to exclude supplement users. We will not study obese children since the response to exogenous vitamin D intervention is reduced.