Dairy is recognized as a key component of a healthy, balanced diet. However, until now it was unclear how long-term dairy intake contributes to the many aspects of bone health in children, including bone density, bone mineral content, and bone area.

In the study, researchers from Boston University gathered information from 106 children, 3 to 5 years of age at the beginning of the study, over a 12-year period. The families enrolled in the study were given food diaries to complete for the child and were asked to record everything the child ate and drank for several days each year.

The researchers used these diaries, along with other standard information, to calculate the children's average daily intake of dairy and other foods.

At the end of the 12-year period, the authors assessed the bone health of the now-adolescent study participants. They found that the adolescents who had consumed 2 or more servings of dairy per day as children had higher levels of bone mineral content and bone density.

Even after adjusting for factors that affect normal bone development, including the child's growth, body size, and activity level, the authors found that these adolescents' average bone mineral content was 175 grams higher than the adolescents who had consumed less than 2 servings of dairy per day.

The researchers also evaluated the combined effects of dairy and other foods consumed by the study participants. Children who consumed 2 or more servings of dairy and 4 ounces of meat or other nondairy protein had bone mineral contents over 300 grams higher than those children with lower intakes of both dairy and other proteins.

The study highlights the importance of dairy intake throughout childhood. "Dairy is a key source of proteins, calcium, and other micronutrients including phosphorus and vitamin D," said lead author Lynn Moore. Parents can promote healthy bone development during adolescence by making dairy a regular part of their child's diet.

(Xinhua News Agency August 14, 2008)