Dairy foods and bone health throughout the lifespan: a critical appraisal of the evidence

Abstract

The consumption of high-Ca, high-protein dairy foods (i.e. milk, cheese, yogurt) is advocated for bone health across the lifespan to reduce the risk of low-trauma fractures. However, to date, the anti-fracture efficacy of dairy food consumption has not been demonstrated in randomised controlled trials but inferred from cross-sectional and prospective studies. The anti-fracture efficacy of dairy food consumption is plausible, but testing this requires a robust study design to ensure outcomes are suitably answering this important public health question. The evidence of skeletal benefits of dairy food consumption is equivocal, not because it may not be efficacious but because the study design and execution are often inadequate. The key issues are compliance with dietary intervention, dropouts, sample sizes and most importantly lack of deficiency before intervention. Without careful appraisal of the design and execution of available studies, precarious interpretations of outcomes may be made from these poorly designed or executed studies, without consideration of how study design may be improved. Dairy food interventions in children are further hampered by heterogeneity in growth: in particular sex and maturity-related differences in the magnitude, timing, location and surface-specific site of bone accrual. Outcomes of studies combining children of different sexes and maturity status may be masked or exaggerated by these differences in growth, so inaccurate conclusions are drawn from results. Until these critical issues in study design are considered in future dairy food interventions, the anti-fracture efficacy of dairy food consumption may remain unknown and continue to be based on conjecture.

A Dairy Product to Reconstitute Enriched with Bioactive Nutrients Stops Bone Loss in High-Risk Menopausal Women without Pharmacological Treatment

“…Therefore, the increase in levels only in the experimental group may be due to the enriched dairy preparation. This is shown in other studies [49,50] that support these results, such as the clinical trial conducted by Manios et al In this study, 79 postmenopausal women were divided into two groups. The control group consumed their usual diet alongside an enriched dairy product, and the intervention group retained their usual diet plus a dairy product enriched with 5.7 g of vitamin D. After 8 weeks of intervention in the winter months, the treatment group had significantly increased serum vitamin levels relative to the control group [51].…”

The Impact of Diet and Physical Activity on Bone Health in Children and Adolescents

“…Children aged between 3 and 17 years seem to take more than 50% of the recommended daily dose of calcium through dairy products as confirmed by studies carried out in France (2005–2007) and the United States ( 49 ). The latter pointed out that children aged between 2 and 18 years take about 950 mg/day through dairy products (especially milk and cheese), which represents the main source ( 55 ). The optimal quantity of phosphorus to take is in a ratio of 2:1 to calcium (in favor of the latter) since it could have the opposite effect.…”

The Role of Milk Components, Pro-, Pre-, and Synbiotic Foods in Calcium Absorption and Bone Health Maintenance

“…Several randomized controlled trials in children and adults have used milk and milk products as the principal source of calcium, all showing positive effects ( 1 ). Early studies in Caucasian and Gambian children indicated that increasing milk intake may increase bone formation, and increase the levels of insulin growth factor—one (IGF-I), while supplementing with fortified milk with additional vitamin D resulted in significant increases in lumbar spine bone density compared to the controls ( 3 ). In contrast a meta-analysis as well as a review indicated that increased milk/ dairy intake may only be effective in children with a low habitual intake ( 2 ).…”

“…Iuliano and Hill ( 3 ) provided a critical appraisal of the evidence for a beneficial effect of dairy foods on bone density/ bone biomarkers throughout the lifespan. Several studies have shown significant effects of regular or fortified milk on bone biomarkers reducing bone resorption, but evidence of significant effects on bone density and reduction in fracture risk are less available.…”

“…Several studies have shown significant effects of regular or fortified milk on bone biomarkers reducing bone resorption, but evidence of significant effects on bone density and reduction in fracture risk are less available. As discussed by Iuliano and Hill ( 3 ), to date no randomized controlled prospective studies have been executed on milk/ dairy foods investigating the anti-fracture effects. In general studies using either calcium supplementation or dairy foods had several flaws such as poor compliance, insufficient numbers of participants, shorter duration of the studies, and a significant drop-out rate which then reduced the opportunity to observe an antifracture effect.…”