Diet, weight-bearing physical activity (WPA) and daylight hours spent outdoors (DE) were related to bone mineral density in the distal (BMDd) and ultradistal (BMDud) forearm of 495 healthy children (8-11 years) and adolescents (11-17 years). BMD was assessed by single photon absorptiometry. Using multiple regression, BMDd was predicted by saturated fat and BMDud by fiber in children. In adolescents, BMDd was predicted by saturated fat and vitamin C, and BMDud by calcium and vitamin C. WPA and DE were not related to BMD. In conclusion, our results showed that current intake of calcium, saturated fat, fiber and vitamin C were positively associated with forearm BMD in children and adolescents. These associations depended on age and bone type. If our findings are verified, dietary recommendations, especially when aimed at young people, may have to be reconsidered.