However, a short-term intervention trial showed that
protein restriction decreased calcium absorption in young
women when daily protein intake was 0.7 and 0.8 g/kg, but
not during the 0.9 or 1.0 g/kg intake period. In addition,
secondary hyperparathyroidism developed in the low protein
groups [116]. More epidemiological evidence highlights
the deleterious effects of a low-protein diet on bone,
where the lowest quartile of dietary protein intake is associated
with a significantly reduced BMD [117].
Other recent studies suggest that the effect of exercise
on bone mass is mediated by diet, not only considering the
individual nutrients, but also total energy intake [118].
Thus, sporting activities that are supposed to be osteogenic
could result in a decrease in bone mass from a negative
energy balance, as has been observed in ballet dancers
[119], amenorrheic runners [118], or young anorexic women
[120].
It has been suggested that many nutrients are related to
bone mass development; therefore, children should consume
a varied and nutrient-dense diet [96]. We also suggest that
exercise must go hand with hand with diet