Study of Vitamin D Fortification of Milk and Oil

Inclusion Criteria: Age between 5 to 80 years at the time of enrolment, Intention to stay in the city for the next two years, Families willing to continue with same brand of oil and milk for next two years after enrolment, Children living with their biological mothers/parents, Families willing to sign a consent form. Exclusion Criteria: History of illness involving calcium or bone metabolism, including stones of the urinary tract, Currently taking vitamin D supplements as treatment of any disease, Receiving immunosuppressive therapy (oral corticosteroids, chemotherapy) during the previous year, Known history of lactose intolerance or other contra-indications or a version to milk intake, Known hypercalcemia or hypercalciuria, Diabetes mellitus or past/current history of renal stones, and any known systemic, endocrine or metabolic disorder, Medications known to interact with vitamin D metabolism (steroids, thiazide diuretics, phenytoin, phenobarbitone, and antitubercular drugs), Hypersensitivity or allergy to any of the components used in nonfortified or fortified milk or oil, Any other reason which in the opinion of a Principal Investigator would interfere with the study shall be excluded.