Why do teenagers need more calcium?

The period from 9-18 years is a critical phase of bone growth and development. These years provide a unique opportunity to maximise bone quality for life. Calcium is among the essential nutrients needed for this process and requirements are therefore increased during this life stage. Milk, yogurt and cheese are a sources of calcium, protein and phosphorus, which contribute to the maintenance of normal bones. Hence the recommendations for this age group are increased to 5 servings per day (as opposed to 3 servings for other age groups).
Extra Information:

In Ireland, 42 % of girls and 23 % of boys aged 13-17 years have inadequate calcium intakes (IUNA, 2008).