Background

We examined whether increased dairy intake was associated with changes in the levels of bone-related biochemical markers in overweight/obese adolescent girls undergoing a 12-week diet and exercise intervention.

Methods

Thirty-five girls were assigned to a low dairy group (LDa; 0–2 servings/day; n = 16) or a higher dairy group (RDa; 4 servings/day; n = 19). Morning, fasted/resting blood samples were collected before and after the intervention and serum concentrations of procollagen-type-1-N-terminal-propeptide (P1NP), β-isomerized-C-terminal-cross-linking-telopeptides (β-CTX), osteocalcin (OC), 25-hydroxyvitamin-D, sclerostin and parathyroid hormone were measured.

Results

At baseline, there were no significant differences between groups in any bone variable. Changes (∆) over time in β-CTΧ (p = 0.035; interaction) and OC (p = 0.015; interaction) were significantly different between groups characterized by decreases in RDa and increases in LDa. P1NP and P1NP:β-CTX ratio decreased in both groups (main time effects: p = 0.003, p = 0.041, respectively). ∆β-CTX (r = −0.37; p = 0.028) and ∆OC (r = −0.39; p = 0.021) were correlated with average number of dairy servings consumed during the study and with each other (r = 0.45; p = 0.006). ∆OC was not correlated with ∆P1NP (r = 0.19; p = 0.27).

Conclusions

Our results suggest that the osteogenic response to a diet and exercise program in this population can be improved with increased dairy intake via a decrease in bone resorption.

Impact