Sodium is required for fluid balance, however no more than 6g daily should be consumed. Overconsumption could result in dehydration.
Calcium
The stage in life when bones are at their strongest is termed peak bone mass. It is estimated 45% of peak bone mass is attained during adolescence, and so adequate calcium intake at this stage is important for the development of dense bone mass.
Most adults reach peak bone mass at around the age of 30. This reduces the risk of fractures and osteoporosis in women in later life.