Temporal change in biomarkers of bone turnover following late evening ingestion of a calcium-fortified, milk-based protein matrix in postmenopausal women with osteopenia

he diurnal rhythm of bone remodeling suggests nocturnal dietary intervention to be most e ective. This study investigated the e ect of bedtime ingestion of a calcium-fortified, milk-derived protein matrix (MBPM) or maltodextrin (CON) on acute (0–4 h) blood and 24-h urinary change in biomarkers of bone remodeling in postmenopausal women with osteopenia. In CON, participants received 804 52 mg calcium, 8.2 3.2 g vitamin D and 1.3 0.2 g/kg BM protein per day. MBPM increased calcium intake to 1679 196 mg, vitamin D to 9.2 3.1 g and protein to 1.6 0.2 g/kg BM. Serum C-terminal cross-linked telopeptide of type I collagen (CTX) and procollagen type 1 amino-terminal propeptide (P1NP), and urinary N-telopeptide cross-links of type I collagen (NTX), pyridinoline (PYD) and deoxypyridinoline (DPD) was measured. Analyzed by AUC and compared to CON, a 􀀀32% lower CTX (p = 0.011, d = 0.83) and 24% (p = 0.52, d = 0.2) increase in P1NP was observed for MBPM. Mean total 24 h NTX excreted in MBPM was 􀀀10% (p = 0.035) lower than CON. Urinary PYD and DPD were una ected by treatment. This study demonstrates the acute e ects of bedtime ingestion of a calcium-fortified, milk-based protein matrix on bone remodeling.