TheEffectsofMilkSupplementationonBone HealthIndicesinAdults:AMeta-Analysisof RandomizedControlledTrials

Abstract

Milkcontainsanumberofbone-beneficialnutrients.However,milk,duetotheD-galactosecontent,mighthaveunfavorableeffectsonbonehealth. Ameta-analysisofrandomizedcontrolledtrials(RCTs)wasperformedtoclarifytheeffectsofmilksupplementationonbonemineraldensity(BMD), boneturnovermarkers[N-terminaltelopeptideoftypeIcollagen(NTx),C-terminaltelopeptideoftype1collagen(CTx),osteocalcin,bonealkaline phosphatase(BALP),andprocollagentype1N-propeptide(P1NP)],andhormonalindicesrelatedtobonemetabolism[parathyroidhormone(PTH), 25-hydroxyvitamin D [25(OH)D], and insulin-like growth factor 1 (IGF-1)] in adults. The PubMed and Web of Science databases were searched. A random-effectsmodelwasusedtoestimatethepooledeffectsizes.Atotalof20RCTswereincluded.Thetrialdurationrangedfrom1moto36mo. Milk supplementation resulted in a small but significant increase in BMD at the hip (+0.004 g/cm2; n=9 RCTs) and lumbar spine (+0.025 g/cm2; n=7),butdidnotsignificantlyaffectwhole-bodyBMD(n=3)andfemoralneckBMD(n=7).Milksupplementationreducedtheconcentrationsof P1NP(–5.20ng/mL;n=9),CTx(–0.16ng/mL;n=9),andNTx(–8.66nmolbonecollagenequivalents/mmolcreatinine;n=3).Theconcentrations of osteocalcin (n=9) and BALP (n=3) were not affected by milk supplementation. Reduced parathyroid hormone PTH (–1.01 pg/mL; n=13) concentrations and increased IGF-1 (+1.79 nmol/l; n = 4) concentrations were observed with milk supplementation. 25(OH)D (+3.73 ng/mL; n=11)concentrationswereincreasedwithvitamin-Dfortifiedmilksupplementation.Theadditionofmilktothedietmaypotentiallyincreasethe likelihood of preventing bone loss by restoring bone homeostasis through the modulation of the calcium-vitamin D-PTH axis, bone remodeling rate,andgrowthhormone/IGF