Double blind trial in 600 children 6-13 years of age residing in 12 boarding schools. Schools will be randomized to distribute three types of milk namely: full fat milk (3% fat), partially defatted milk (2% fat) or defatted milk (1% fat) for 90 days of effective exposure (4 months total duration). Subjects will receive 400 mL of the corresponding milk every day (200 mL breakfast and 200 mL night meal) from Monday through Friday. During week ends they will eat a freely chosen diet at home. Milk intake will be measured every day. Diet by 24 h-recall. will be evaluated every month. Blood samples will be obtained at the beginning and at the end of the intervention.