Effects of Dairy Consumption on Body Composition and Bone Properties in Youth: A Systematic Review

Animal board invited review: Dietary transition from animal to plant-derived foods: Are there risks to health?

Animal-derived foods (ADFs) are a very varied group of foods, but many are nutrient rich and contain higher quality protein than provided by plant-derived foods such that a simple replacement of ADF protein is likely to lead to a reduction in overall protein quality. In addition, many ADFs are richer in some nutrients than plant-based foods (e.g. Fe, Ca) and these often have a higher bioavailability. ADFs also provide nutrients that plants cannot supply (e.g. vitamin B12) and some provide beneficial health functionality (e.g. hypotensive) which is not explained by traditional nutrition. However, there remains a good health reason to increase the proportion of plant-derived food in many diets to increase the intake of dietary fibre which is often consumed at very sub-optimal levels. It seems logical that the increased plant-derived foods should replace the ADFs that have the least benefit, the greatest risk to health and the highest environmental impact. Processed meat fits these characteristics and should be an initial target for replacement with plant-based based protein-rich foods that additionally provide the necessary nutrients and have high-quality dietary fibre. Processed meat covers a wide range of products including several traditional foods (e.g. sausages) which will make decisions on food replacement challenging. There is therefore an urgent need for research to better define the relative health risks associated with the range of processed meat-based foods. The aim of this review is to examine the evidence on the benefits and risks of this dietary transition including the absolute necessity to consider initial nutrient status before the replacement of ADFs is considered.

A review of dairy food intake for improving health among black children and adolescents in the US

Adequate nutrition during childhood and adolescence is crucial for proper neurological, musculoskeletal, immunological, and cardiometabolic health and development. Yet, disparities among socially underserved racial/ethnic groups in the United States (US) provide significant challenges to achieving adequate nutrition during these years of rapid growth and maturation. For example, Black children and adolescents are at greater risk for having food insecurity, lower-quality diets, obesity, and numerous associated health challenges that result from these disparities compared to their White peers. A growing body of evidence indicates that improving diet quality is critical for improving childhood and adolescent health and well-being, and that the diverse nutritional profile and bioactive compounds found within dairy foods may play multiple roles in promoting proper growth and development during these life stages. Therefore, to support overall health and development among Black youth, greater education and implementation efforts are needed to help this population meet the national dietary recommendations of 2.5 to 3 servings of dairy foods per day. Continuing to fall short of these recommendations puts Black children and adolescents at risk of multiple nutrient inadequacies and health disparities that can have lifelong impacts on disease development, mental health, and quality of life. This review presents the state of knowledge on health disparities and modifiable nutritional strategies involving milk and dairy foods to support the growth and maturation of children and adolescents, with a special focus on Black youth in the US.

Non-targeted metabolomics identifies biomarkers in milk with high and low milk fat percentage

Milk is widely recognized as an important food source with health benefits. Different consumer groups have different requirements for the content and proportion of milk fat; therefore, it is necessary to investigate the differential metabolites and their regulatory mechanisms in milk with high and low milk fat percentages (MFP). In this study, untargeted metabolomics was performed on milk samples from 13 cows with high milk fat percentage (HF) and 13 cows with low milk fat percentage (LF) using ultra-high performance liquid chromatography coupled with mass spectrometry (UHPLC-MS/MS). Forty-eight potential differentially labeled compounds were screened using the orthogonal partial least squares-discriminant analysis (OPLS-DA) combined with the weighted gene co-expression network analysis (WGCNA) method. Amino acid metabolism was the key metabolic pathway with significant enrichment of L-histidine, 5-oxoproline, L-aspartic acid, and L-glutamic acid. The negative correlation with MFP differentiated the HF and LF groups. To further determine the potential regulatory role of these amino acids on milk fat metabolism, the expression levels of marker genes in the milk fat synthesis pathway were explored. It was noticed that L-histidine reduced milk fat concentration primarily by inhibiting the triglycerides (TAG) synthesis pathway. L-aspartic acid and L-glutamic acid inhibited milk fat synthesis through the fatty acid de novo and TAG synthesis pathways. This study provides new insights into the mechanism underlying milk fat synthesis and milk quality improvement.

Adherence to the Mediterranean diet in young male soccer players

INTRODUCTION

Nutrition is vital in health and sports performance by improving anthropometric-related parameters and dietary habits, especially in the youngest ages. The Mediterranean diet (MD) has been highly recognized for its positive health effects and low adverse environmental impact.

OBJECTIVES

We aimed to characterize adherence to the MD and analyze its association with anthropometric parameters in young soccer players.

METHODOLOGY

In the present study, 132 male young soccer players from under 9 to under 15 categories (aged 7 to 15 years) from a Portuguese football club participated. The Mediterranean Diet Quality Index for Children and Adolescents (KIDMED) questionnaire was applied to assess adherence to the MD. Anthropometric-related parameters, including body mass, height, triceps skinfold thickness (TSKF), suprailiac skinfold thickness (SISKF), body mass index (BMI) and body fat percentage (%BF), were determined. The differences between groups were performed accordingly to normal and non-normal distribution. Spearman's correlations were performed to analyze the hypothetical correlation between KIDMED and BMI.

RESULTS

Players reached an average KIDMED score of 8.36 ± 1.92, showing that 68.2% (n = 90) reached high adherence to the MD, 31.1% (n = 41) had moderate adherence to the MD, and 0.78% (n = 1) had poor adherence to the MD. When the analysis was made for age group and BMI classification, no significant differences were observed in adherence to the MD. Considering the main characteristics of the MD, 50.8% consumed fruit (vs. 49,2%), 52.3% consumed vegetables (vs. 47,7%), and only 20% consumed oleaginous dried fruits (vs. 80%). Dairy consumption throughout the day was 49,2% (vs. no: 50,8%).

CONCLUSION

Data from the present study showed that many soccer players adhered to the MD, and no differences were observed for age group or BMI classification.

The Effects of Dairy Product Supplementation on Bone Health Indices in Children Aged 3 to 18 Years: A Meta-Analysis of Randomized Controlled Trials

Childhood and adolescence are critical periods for optimizing skeletal growth. Dairy products are valuable sources of bone-beneficial nutrients, particularly calcium and protein. A random-effects meta-analysis of published randomized controlled trials was performed to quantitatively assess the effects of dairy supplementation on bone health indices in children and adolescents. The PubMed and Web of Science databases were searched. Dairy supplementation increased whole-body bone mineral content (BMC) (+25.37 g) and areal bone mineral density (aBMD) (+0.016 g/cm2), total hip BMC (+0.49 g) and aBMD (+0.013 g/cm2), femoral neck BMC (+0.06 g) and aBMD (+0.030 g/cm2), lumbar spine BMC (+0.85 g) and aBMD (+0.019 g/cm2), and height (0.21 cm). When expressed as a percentage difference, whole-body BMC was increased by 3.0%, total hip BMC by 3.3%, femoral neck BMC by 4.0%, lumbar spine BMC by 4.1%, whole-body aBMD by 1.8%, total hip aBMD by 1.2%, femoral neck aBMD by 1.5%, and lumbar spine aBMD by 2.6%. Dairy supplementation increased serum insulin-like growth factor I concentrations (19.89 nmol/L) and reduced concentrations of urinary deoxypyridinoline (-1.78 nmol/mmol creatinine) and serum parathyroid hormone (-10.46 pg/mL) but did not significantly affect the serum concentrations of osteocalcin, bone alkaline phosphatase, and C-terminal telopeptide of type 1 collagen. Serum 25-hydroxyvitamin D concentrations (+4.98 ng/mL) increased with vitamin D-fortified dairy supplementation. The positive effects on bone mineral mass parameters and height were generally consistent across subgroups defined by sex, geographical region, baseline calcium intake, calcium from the supplementation, trial duration, and Tanner stages. In summary, dairy supplementation during growth leads to a small but significant increase in bone mineral mass parameters, and these findings are generally supported by the changes in several biochemical parameters related to bone health.

Friend or Foe? The Role of Animal-Source Foods in Healthy and Environmentally Sustainable Diets

Scientific and political discussions around the role of animal-source foods (ASFs) in healthy and environmentally sustainable diets are often polarizing. To bring clarity to this important topic, we critically reviewed the evidence on the health and environmental benefits and risks of ASFs, focusing on primary trade-offs and tensions, and summarized the evidence on alternative proteins and protein-rich foods. ASFs are rich in bioavailable nutrients commonly lacking globally and can make important contributions to food and nutrition security. Many populations in Sub-Saharan Africa and South Asia could benefit from increased consumption of ASFs through improved nutrient intakes and reduced undernutrition. Where consumption is high, processed meat should be limited, and red meat and saturated fat should be moderated to lower noncommunicable disease risk-this could also have cobenefits for environmental sustainability. ASF production generally has a large environmental impact; yet, when produced at the appropriate scale and in accordance with local ecosystems and contexts, ASFs can play an important role in circular and diverse agroecosystems that, in certain circumstances, can help restore biodiversity and degraded land and mitigate greenhouse gas emissions from food production. The amount and type of ASF that is healthy and environmentally sustainable will depend on the local context and health priorities and will change over time as populations develop, nutritional concerns evolve, and alternative foods from new technologies become more available and acceptable. Efforts by governments and civil society organizations to increase or decrease ASF consumption should be considered in light of the nutritional and environmental needs and risks in the local context and, importantly, integrally involve the local stakeholders impacted by any changes. Policies, programs, and incentives are needed to ensure best practices in production, curb excess consumption where high, and sustainably increase consumption where low.

Effects of foods, beverages and macronutrients on BMI z-score and body composition in children and adolescents: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

A healthy diet is fundamental for healthy growth and for future disease prevention. However, scientific consensus on how to compose healthy diets for children has not been established. Therefore, a systematic review and meta-analysis was performed to investigate if an independent effect exists between foods, beverages or the composition of macronutrients and body composition in children and adolescents.

METHODS

A systematic search was performed in four databases up to July 2021. A systematic review of randomized controlled studies (RCTs) and meta-analyses were carried out by extracting mean difference (MDs) and standard deviation (SD) and performed using the random effect model.

RESULTS

Sixteen RCTs met inclusion criteria. Beyond dairy, sugar-sweetened beverages and macronutrient composition, no trials were identified for other food groups. Based on five RCTs (n:5), a higher-dairy diet was found to reduce body fat percentage - 0.47 [- 0.92, - 0.03] (p = 0.04). A higher-dairy diet was also found to increase lean body mass (kg) 0.34 [0.06, 0.62] (p = 0.02) (n:2), but did not affect BMI z-score - 0.05 [- 0.16, 0.06] (p = 0.39) (n:4). Substituting sugar-sweetened beverage with non-caloric beverages or flavored milk reduced body fat percentage (- 0.70 [- 0.78, - 0.62] (p < 0.001)) (n:3) but did not change BMI z-score (- 0.05 [- 0.20, 0.09] (p = 0.48)) (n:2). No significant effects were found between different macronutrient compositions and BMI z-score or body fat percentage.

CONCLUSION

Changes in diet from low to higher-dairy consumption and from sugar-sweetened beverages to non-caloric beverages or flavored milk resulted in favorable changes in body composition among children and adolescents. Eligible studies investigating other foods are lacking.

TRIAL REGISTRATION

PROSPERO registration number (CRD42020173201).

Cheese Intake is Inversely Associated with LDL Cholesterol in Young Children

Purpose: To determine if intake (servings/day) of total dairy and/or dairy subtypes (milk, cheese, and yogurt) were associated with biomarkers related to dyslipidemia, insulin sensitivity and inflammation in a sample of cardio-metabolically healthy young children from the Guelph Family Health Study at the University of Guelph, Guelph, Ontario, Canada.Methods: Baseline data from 42 children (aged 2.0-6.2 years) from 33 families who provided a dietary assessment and a fasted blood sample were included in this cross-sectional analysis. Linear and logistic regressions using generalized estimating equations were used for analysis and models were adjusted for age, gender, and household income.Results: In total, 42 children (3.74 ± 1.23 years old; mean (± SD)) consumed median (25th percentile, 75th percentile) servings/day of 1.70 (1.16, 2.81) for total dairy, 0.74 (0.50, 1.70) for milk, 0.63 (0.00, 1.16) for cheese, and 0.00 (0.00, 0.38) for yogurt. Cheese intake was significantly inversely associated with LDL cholesterol (-0.16 (95% CI: -0.29, -0.03) mmol/L per serving; P = 0.02)). No other associations between dairy intake and biomarkers were significant.Conclusions: Cheese intake was inversely associated with LDL cholesterol in this preliminary study of cardio-metabolically healthy young children, thereby warranting further research on dairy intake and cardiometabolic risk factors.

Association of cow's milk intake in early childhood with adiposity and cardiometabolic risk in early adolescence

BACKGROUND

Prior studies have provided conflicting evidence regarding associations of pediatric milk consumption with subsequent adiposity.

OBJECTIVES

We aimed to estimate associations of the consumption frequency and fat content of early childhood milk intake with early adolescent adiposity and cardiometabolic risk.

METHODS

We analyzed data collected prospectively from 796 children in Project Viva, a Boston-area prebirth cohort. Parents reported the frequency (times/day) and fat content [higher-fat: whole (3.25%) or 2% milk; lower-fat: 1% or skim milk] of cow's milk consumed in early childhood (mean, 3.2 years) via food-frequency questionnaires. We measured adiposity and cardiometabolic markers in early adolescence (mean, 13.2 years) and conducted multivariable regressions to assess associations adjusted for baseline parental and child sociodemographic, anthropometric, and dietary factors.

RESULTS

In early childhood, mean milk intake was 2.3 times/day (SD, 1.2 times/day), and 63% of children drank primarily higher-fat milk. The early childhood BMI z-score (BMIz) was inversely associated with the fat content of milk consumed in early childhood. After adjustment for baseline parent and child factors, early childhood intake of higher-fat compared with lower-fat milk was associated with lower adiposity; however, the 95% CIs for most adiposity outcomes-except for the odds of overweight or obesity (OR, 0.60; 95% CI, 0.38-0.93)-crossed the null after adjustment for the baseline child BMIz and BMIz change between ages 2 and 3 years. Early childhood consumption of higher-fat milk (compared with lower-fat milk) was not associated with adverse cardiometabolic outcomes. The frequency of cow's milk consumption in early childhood was not associated with adiposity or cardiometabolic risk in early adolescence.

CONCLUSIONS

Consumption of higher-fat cow's milk in early childhood was not associated with increased adiposity or adverse cardiometabolic health over a decade later. Our findings do not support current recommendations to consume lower-fat milk to reduce the risk of later obesity and adverse cardiometabolic outcomes. This trial was registered at clinicaltrials.gov as NCT02820402.

Associations between Frequency of Dairy Intake with Body Composition and Excess Adiposity in Preschool Children from Poland

Evidence suggests there has been a decrease in childhood dairy consumption. There is a need for further studies to evaluate the types of dairy products in relation to the risk of obesity in pediatric population. The aim of the study was to determine the associations between the frequency of consumption of different types of dairy products and body composition and excess adiposity in preschool children from Poland. A cross-sectional study of 1172 children aged 5–6 years was conducted using a bioelectrical impedance analysis for body composition estimation and a modified food frequency questionnaire (FFQ-6) to assess the habitual diets of the participants. Among the analyzed dairy products, milk was consumed most often, followed by fruit yoghurts, yellow cheese, and cottage cheese, and natural yoghurt was the least common. Participants that consumed fruit or natural yoghurt more frequently had higher adipose tissue content. The logistic regression analysis by the method of forward selection showed that more frequent consumption of fruit yoghurt significantly increased the risk of excess adiposity among the total sample (OR = 1.20, p < 0.001). This study revealed that higher consumption of fruit yoghurt could be significant determinant of excess adiposity in Polish preschool children.

Evaluation of Increasing Dairy Intake on Bone Density in Post-pubertal Youth: A Randomized Controlled Trial Using Motivational Interviewing

BACKGROUND

Adequate nutrition is important for bone health, especially for bone mineral accretion.

OBJECTIVE

The primary objective tested whether increasing dairy intake using the motivational interviewing technique (MInt) improves lumbar spine (LS) bone mineral density (BMD) after 2 years in post-pubertal adolescents with habitual dairy intake of < 2 dairy servings/day.

DESIGN

Participants (14-18.9 y) were randomized to: Group 1 (control), group 2 (target of 3 dairy servings/d), or group 3 (target of ≥ 4 dairy servings/d) for 12 months with groups 2 and 3 using MInt, with an additional 12-month non-intervention follow-up. The primay outcome was LS BMD, and secondary outcomes: whole body (WB), total hip (TH), and 33% distal radius BMD using dual-energy x-ray absorptiometry, bone geometry using peripheral quantitative computed tomography, and bone biomarkers.

RESULTS

Ninety-four adolescents (16.6 ± 1.5 y) were recruited. Seventy-six (80.9%) completed the 12-month assessments. From baseline to 12 months, dairy intake in female groups 2 and 3 increased by 107% and 208%, respectively; and by 48% and 153% in males of group 2 and 3, respectively. In females, group 3 had greater increases in THBMD (4.3 to 7.5%) compared to control (3.7 to 4.9%, P = 0.04) and group 2 (0.0 to 1.7%, P = 0.04) at 12 and 24 months. No effects due to dairy intake were observed for DXA outcomes in males or radial and tibial volumetric BMD in both sexes. None of the bone biomarkers were different among the dairy groups in females or males.

CONCLUSION

MInt effectively increased dairy intake with benefits to bone health only in female adolescents with previously low calcium intake who consumed 4 dairy serving or more/day for 12 months. Larger studies are required to explain the lack of intervention effect in males.This trial was registered at ClinicalTrials.gov as. NCT02236871.

Dairy products and bone health

Bone mineral mass, geometry and microstructure, hence determinants of fracture risk, result bone accrual during growth and bone loss later in life. Peak bone mass, which is reached by the end of the second decade of life, is mainly determined by genetic factors. Among other factors influencing bone capital, dietary intakes, particularly calcium and protein, play a significant role in peak bone mass attainment. Both nutrients are provided in dairy products, which accounts for 50-60% and 20-30% of the daily calcium and protein intakes, respectively. Children avoiding dairy products are at higher risk of fracture, as are adults or older individuals following a diet devoid of dairy products, like vegans. Various intervention trials have shown some beneficial effects of dairy products on bone capital accumulation during growth and on bone turnover in adults. In observational studies, dairy products intake, particularly the fermented ones, which also provide probiotics in addition to calcium, phosphorus and protein, appear to be associated with a lower risk of hip fracture.

Effect of milk supplementation on the status of micronutrients among rural school children aged 5–19 years in a tribal predominating district of India

Background

In the tribal state of Jharkhand, there have been very few studies on micronutrient deficiency and how it is addressed among school children. This study was conceived and undertaken to assess the effect of milk supplementation on the micronutrient status of school children.

Design

A comparative observational study was conducted among school children of a tribal district in India during 2017–2018. Two groups of schools/clusters were randomly selected, one with milk supplementation and the other without supplementation. A total of 318 children from the two groups of schools were recruited for biochemical analysis of certain micronutrients, such as calcium, vitamin D, vitamin B₁₂ and iron (haemoglobin level), using cluster random sampling. Data were analysed using SPSS V.20.0 software, and multiple logistic regression analysis was done to determine the predictors of serum calcium and vitamin B₁₂ level among school children.

Results

Almost all children from both groups had vitamin D deficiency. A higher risk of lower serum vitamin B₁₂ level (OR 2.59, 95% CI 1.61 to 4.16) and calcium level (OR 3.36, 95% CI 1.74 to 6.49) was observed in children of the control group. The difference in the proportion of anaemia in the two study groups was found to be statistically insignificant. Milk consumption was found to be the only significant predictor of normal vitamin B₁₂ and calcium level in the present study.

Conclusions

In this study, it was concluded that milk consumption may help in improving the calcium and vitamin B₁₂ status of school children of a tribal state, whereas it does not have any significant effect on vitamin D level.

Nutritional intake and bone health

Osteoporotic or fragility fractures affect one in two women and one in five men who are older than 50. These events are associated with substantial morbidity, increased mortality, and an impaired quality of life. Recommended general measures for fragility fracture prevention include a balanced diet with an optimal protein and calcium intake and vitamin D sufficiency, together with regular weight-bearing physical exercise. In this narrative Review, we discuss the role of nutrients, foods, and dietary patterns in maintaining bone health. Much of this information comes from observational studies. Bone mineral density, microstructure-estimated bone strength, and trabecular and cortical microstructure are positively associated with total protein intake. Several studies indicate that fracture risk might be lower with a higher dietary protein intake, provided that the calcium supply is sufficient. Dairy products are a valuable source of these two nutrients. Hip fracture risk appears to be lower in consumers of dairy products, particularly fermented dairy products. Consuming less than five servings per day of fruit and vegetables is associated with a higher hip fracture risk. Adherence to a Mediterranean diet or to a prudent diet is associated with a lower fracture risk. These various nutrients and dietary patterns influence gut microbiota composition or function, or both. The conclusions of this Review emphasise the importance of a balanced diet including minerals, protein, and fruit and vegetables for bone health and in the prevention of fragility fractures.

Interactions between Growth of Muscle and Stature: Mechanisms Involved and Their Nutritional Sensitivity to Dietary Protein: The Protein-Stat Revisited

Childhood growth and its sensitivity to dietary protein is reviewed within a Protein-Stat model of growth regulation. The coordination of growth of muscle and stature is a combination of genetic programming, and of two-way mechanical interactions involving the mechanotransduction of muscle growth through stretching by bone length growth, the core Protein-Stat feature, and the strengthening of bone through muscle contraction via the mechanostat. Thus, growth in bone length is the initiating event and this is always observed. Endocrine and cellular mechanisms of growth in stature are reviewed in terms of the growth hormone-insulin like growth factor-1 (GH-IGF-1) and thyroid axes and the sex hormones, which together mediate endochondral ossification in the growth plate and bone lengthening. Cellular mechanisms of muscle growth during development are then reviewed identifying (a) the difficulties posed by the need to maintain its ultrastructure during myofibre hypertrophy within the extracellular matrix and the concept of muscle as concentric "bags" allowing growth to be conceived as bag enlargement and filling, (b) the cellular and molecular mechanisms involved in the mechanotransduction of satellite and mesenchymal stromal cells, to enable both connective tissue remodelling and provision of new myonuclei to aid myofibre hypertrophy and (c) the implications of myofibre hypertrophy for protein turnover within the myonuclear domain. Experimental data from rodent and avian animal models illustrate likely changes in DNA domain size and protein turnover during developmental and stretch-induced muscle growth and between different muscle fibre types. Growth of muscle in male rats during adulthood suggests that "bag enlargement" is achieved mainly through the action of mesenchymal stromal cells. Current understanding of the nutritional regulation of protein deposition in muscle, deriving from experimental studies in animals and human adults, is reviewed, identifying regulation by amino acids, insulin and myofibre volume changes acting to increase both ribosomal capacity and efficiency of muscle protein synthesis via the mechanistic target of rapamycin complex 1 (mTORC1) and the phenomenon of a "bag-full" inhibitory signal has been identified in human skeletal muscle. The final section deals with the nutritional sensitivity of growth of muscle and stature to dietary protein in children. Growth in length/height as a function of dietary protein intake is described in the context of the breastfed child as the normative growth model, and the "Early Protein Hypothesis" linking high protein intakes in infancy to later adiposity. The extensive paediatric studies on serum IGF-1 and child growth are reviewed but their clinical relevance is of limited value for understanding growth regulation; a role in energy metabolism and homeostasis, acting with insulin to mediate adiposity, is probably more important. Information on the influence of dietary protein on muscle mass per se as opposed to lean body mass is limited but suggests that increased protein intake in children is unable to promote muscle growth in excess of that linked to genotypic growth in length/height. One possible exception is milk protein intake, which cohort and cross-cultural studies suggest can increase height and associated muscle growth, although such effects have yet to be demonstrated by randomised controlled trials.

Differences in Diet Quality between School Lunch Participants and Nonparticipants in the United States by Income and Race

Prior research has shown that participation in the United States' National School Lunch Program (NSLP) is associated with consuming higher-quality lunches and diets overall, but little is known about differences by income and race/ethnicity. This analysis used 24 h dietary recall data from the School Nutrition and Meal Cost Study to examine how NSLP participation affects the diet quality of students in different income and racial/ethnic subgroups. Diet quality at lunch and over 24 h was assessed using the Healthy Eating Index (HEI)-2010, where higher scores indicate higher-quality intakes. HEI-2010 scores for NSLP participants and nonparticipants in each subgroup were estimated, and two-tailed t-tests were conducted to determine whether participant-nonparticipant differences in scores within each subgroup were statistically significant. NSLP participants' lunches received significantly higher total HEI-2010 scores than those of nonparticipants for lower-income, higher-income, non-Hispanic White, and non-Hispanic Black students, suggesting that participating in the NSLP helps most students consume healthier lunches. These significantly higher total scores for participants' lunch intakes persisted over 24 h for higher-income students and non-Hispanic White students but not for lower-income students or students of other races/ethnicities. For NSLP participants in all subgroups, the nutritional quality of their 24 h intakes was much lower than at lunch, suggesting that the positive influence of the NSLP on their overall diet quality was negatively influenced by foods consumed the rest of the day (outside of lunch).

Dairy product intake decreases bone resorption following a 12-week diet and exercise intervention in overweight and obese adolescent girls

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

We demonstrated that bone resorption significantly decreased over the intervention period in the group consuming adequate levels of dairy products compared to the group consuming little to no dairy products. Change in bone resorption was negatively correlated with average number of dairy servings consumed during the study. 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. This is the first study to date to assess changes in bone marker status following a lifestyle intervention with exercise and different intakes of dairy products in a sample of OW/OB adolescent girls. We provide evidence that increased dairy product intake is associated with beneficial changes in circulating levels of bone-related biochemical markers in these girls undergoing a 12-week lifestyle (nutrition counseling and exercise training) intervention program. The main impact of our work relates particularly to the recent changes to Canada's food guide. Using the old recommendations, we demonstrated that the inclusion of 3-4 servings of mixed dairy foods per day improved bone health (primarily as a decrease in resorption) in OW/OB adolescent girls and that this level of dairy product intake appears appropriate and should still be encouraged for this age group. We also demonstrated that adolescent girls, a group that usually does not sufficiently consume dairy products, also improved their BMI percentile and nutrient intake with the inclusion of dairy products in their diets.

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

Increasing peak bone mass during adolescence and reducing bone loss in later life are two approaches to reduce the risk of osteoporosis with aging. Osteoporosis affects a large proportion of the elderly population worldwide and the incidence is increasing. Milk consumption is an accepted strategy in building peak bone mass and therefore may reduce the risk of osteoporosis. In childhood calcium, phosphorous, and growth factors are the important components to support bone growth but in adults the positive influence on bone density/maintenance may also be due to other bioactive proteins/peptides or lipids in milk acting directly in the gastrointestinal tract (GIT). Lactose has been known to increase calcium absorption; galactooligosaccharides (GOS) are derived from lactose and are non-digestible oligosaccharides. They have been shown to improve mineral balance and bone properties as well as causing increases in bifidobacteria in the gut, therefore a prebiotic effect. Supplementation with fortified milk and dairy products with added prebiotics, increased both calcium and magnesium absorption and caused some modulation of gut microbiota in animals and humans. Fermented milk is now also recognized to contain highly active components such as vitamins, peptides, oligosaccharides, and organic acids. In this review, the role of milk and milk components in improving calcium absorption and thereby supporting bone health is discussed. In addition, some reference is made to the significance of combining the inherent beneficial components from milk with fortificants/nutrients that will support bone health through adulthood. Novel data suggesting differences in diversity of the microbiota between healthy and osteoporotic women are provided.

Systematic review and meta-analysis of the association between dairy consumption and the risk of hip fracture: critical interpretation of the currently available evidence

In the present meta-analysis, reductions in the risk of hip fracture with milk consumption were only observed among American adults, but not among Scandinavian adults, possibly because milk products are more commonly fortified with vitamin D in the former population than in Scandinavian countries. The reduction in the risk of hip fracture was also observed with yogurt consumption, which is often associated with healthy lifestyles and dietary patterns that contribute to improved bone health.

INTRODUCTION

Although dairy products contain bone-beneficial nutrients, the association between dairy consumption and the risk of hip fracture remains equivocal. Fueling this uncertainty, the elevated risk of hip fracture in association with milk consumption was observed in a cohort of Swedish women. A systematic review and meta-analysis of prospective cohort studies was performed to critically evaluate the association, or lack thereof, between dairy consumption (milk, yogurt, and cheese) and the risk of hip fracture.

METHODS

A random effects model was used to generate the summary relative risks (RRs) with their 95% confidence intervals (CIs) for the associations of interest.

RESULTS

In the meta-analysis of the highest versus lowest category of consumption, higher consumption of yogurt (RR 0.78, 95% CI 0.68, 0.90), but not milk (RR 0.86, 95% CI 0.73, 1.02) or cheese (RR 0.85, 95% CI 0.66, 1.08), was associated with a lower risk of hip fracture. For milk, the reduced risk of fracture with higher milk consumption was observed in the USA (RR 0.75, 95% CI 0.65, 0.87), but not in Scandinavian countries (RR 1.00, 95% CI 0.85, 1.17). These findings were further supported by the fact that American studies (RR 0.93, 95% CI 0.88, 0.98; per 1 glass/day), but not Scandinavian studies (RR 1.01, 95% CI 0.95, 1.07; per 1 glass/day), demonstrated a linear association between milk consumption and the risk of hip fracture.

CONCLUSIONS

The cumulative evidence from prospective cohort studies reassuringly suggests that the risk of hip fracture may not be elevated among people who consume milk, yogurt, and cheese, and that a greater consumption of milk or yogurt may even be associated with a lower risk of hip fracture depending on the factors that may differ across the population of interest.

Comparison of methodological quality between the 2007 and 2019 Canadian dietary guidelines

OBJECTIVE

With significant shifts in the dietary recommendations between the 2007 and 2019 Canadian dietary guidelines, such as promoting plant-based food intake, reducing highly processed food intake and advocating the practice of food skills, we compared their differences in guideline development methods.

DESIGN

Two reviewers used twenty-five guided criteria to appraise the methods used to develop the most recent dietary guidelines against those outlined in the 2014 WHO Handbook for Guideline Development.

SETTING

Canada.

PARTICIPANTS

2007 and 2019 dietary guidelines.

RESULTS

We found that the 2019 guidelines were more evidence-based and met 80 % (20/25) of the WHO criteria. For example, systematic reviews and health organisation authoritative reports, but not industry reports, constituted the evidence base for the dietary recommendations. However, recommendations on food sustainability and food skill practice were driven primarily by stakeholders' interests. By contrast, less information was recorded about the process used to develop the 2007 guidelines, resulting in 24 % (6/25) consistency with the WHO standards.

CONCLUSIONS

Our analysis suggests that a more transparent and evidence-based approach is used to develop the 2019 Canadian dietary guidelines and that method criteria should support further incorporation of nutrition priorities (food sustainability and food skills) in future dietary guideline development.

Whole milk compared with reduced-fat milk and childhood overweight: a systematic review and meta-analysis

BACKGROUND

The majority of children in North America consume cow-milk daily. Children aged >2 y are recommended to consume reduced-fat (0.1-2%) cow-milk to lower the risk of obesity.

OBJECTIVES

To evaluate the relation between cow-milk fat consumption and adiposity in children aged 1-18 y.

METHODS

Embase (Excerpta Medica Database), CINAHL (Cumulative Index to Nursing and Allied Health Literature), MEDLINE, Scopus, and Cochrane Library databases from inception to August 2019 were used. The search included observational and interventional studies of healthy children aged 1-18 y that described the association between cow-milk fat consumption and adiposity. Two reviewers extracted data, using the Newcastle-Ottawa Scale to assess risk of bias. Meta-analysis was conducted using random effects to evaluate the relation between cow-milk fat and risk of overweight or obesity. Adiposity was assessed using BMI z-score (zBMI).

RESULTS

Of 5862 reports identified by the search, 28 met the inclusion criteria: 20 were cross-sectional and 8 were prospective cohort. No clinical trials were identified. In 18 studies, higher cow-milk fat consumption was associated with lower child adiposity, and 10 studies did not identify an association. Meta-analysis included 14 of the 28 studies (n = 20,897) that measured the proportion of children who consumed whole milk compared with reduced-fat milk and direct measures of overweight or obesity. Among children who consumed whole (3.25% fat) compared with reduced-fat (0.1-2%) milk, the OR of overweight or obesity was 0.61 (95% CI: 0.52, 0.72; P < 0.0001), but heterogeneity between studies was high (I2 = 73.8%).

CONCLUSIONS

Observational research suggests that higher cow-milk fat intake is associated with lower childhood adiposity. International guidelines that recommend reduced-fat milk for children might not lower the risk of childhood obesity. Randomized trials are needed to determine which cow-milk fat minimizes risk of excess adiposity. This systematic review and meta-analysis was registered with PROSPERO (registration number: CRD42018085075).

Quantitative Ultrasound and Dual X-Ray Absorptiometry as Indicators of Bone Mineral Density in Young Women and Nutritional Factors Affecting It

Young adulthood is an important stage in the accrual of bone mass. Young women are often unaware of the need, and how to optimize modifiable risk factors, particularly intake of nutrients associated with good bone health. In this study, an accessible way to estimate osteoporosis risk, quantitative ultrasound (QUS), is compared to the gold-standard technique dual X-ray absorptiometry (DXA) in a group of 54 healthy young women (18–26 years) from Manawatu, New Zealand, and the relationship with nutrient intake is investigated. Broadband ultrasound attenuation and speed of sound (BUA, SOS) were assessed by QUS calcaneal scans and bone mineral concentration/density (BMC/BMD) were determined by DXA scans of the lumbar spine and hip (total and femoral neck). Dietary intake of energy, protein, and calcium was estimated using three-day food diaries and questionnaires. DXA mean Z-scores (>−2.0) for the hip (0.19) and spine (0.2) and QUS mean Z-scores (>−1.0) (0.41) were within the expected ranges. DXA (BMD) and QUS (BUA, SOS) measurements were strongly correlated. Median intakes of protein and calcium were 83.7 g/day and 784 mg/day, respectively. Protein intake was adequate and, whilst median calcium intake was higher than national average, it was below the Estimated Average Requirement (EAR). No significant relationship was found between dietary intake of calcium or protein and BMD or BMC. To conclude, QUS may provide a reasonable indicator of osteoporosis risk in young women but may not be an appropriate diagnostic tool. Increased calcium intake is recommended for this group, regardless of BMD.

A critical review of the role of milk and other dairy products in the development of obesity in children and adolescents

Existing reviews suggest that milk and other dairy products do not play a role in the development of obesity in childhood, but they do make an important contribution to children's nutrient intake. It is thus curious that public health advice on the consumption of dairy products for children is often perceived as unclear. The present review aimed to provide an overview of the totality of the evidence on the association between milk and other dairy products, and obesity and indicators of adiposity, in children. Our search identified forty-three cross-sectional studies, thirty-one longitudinal cohort studies and twenty randomised controlled trials. We found that milk and other dairy products are consistently found to be not associated, or inversely associated, with obesity and indicators of adiposity in children. Adjustment for energy intake tended to change inverse associations to neutral. Also, we found little evidence to suggest that the relationship varied by type of milk or dairy product, or age of the children, although there was a dearth of evidence for young children. Only nine of the ninety-four studies found a positive association between milk and other dairy products and body fatness. There may be some plausible mechanisms underlying the effect of milk and other dairy products on adiposity that influence energy and fat balance, possibly through fat absorption, appetite or metabolic activity of gut microbiota. In conclusion, there is little evidence to support a concern to limit the consumption of milk and other dairy products for children on the grounds that they may promote obesity.

Is A Healthy Diet Associated with Lower Anthropometric and Glycemic Alterations in Predisposed Children Born from Mothers with Gestational Diabetes Mellitus?

Children born from mothers with gestational diabetes mellitus (GDM) are at high-risk of obesity and type 2 diabetes. To date, there is a lack of effective strategies to prevent these complications. The aim of this study was to evaluate the association between diet quality and anthropometric and glycemic profiles of children exposed (GDM+) and unexposed (GDM⁻) to GDM. A total of 104 GDM+ and 38 GDM⁻ children were included. Two 24-h dietary recall questionnaires were used to assess dietary intakes. The Healthy Eating Index adapted for the Canadian population (HEI-C) was used to assess diet quality. Spearman correlations adjusted for children's age and sex were computed. Mean age was 6.0 ± 2.5 and 6.8 ± 2.3 years for GDM+ and GDM⁻, respectively (p = 0.03). Total HEI-C score was negatively associated with the android-to-gynoid fat mass ratio (r = -0.29, p = 0.03) and homeostasis model assessment for insulin resistance (HOMA-IR) index (r = -0.22, p = 0.04) in GDM+ children only. The prevalence of being overweight or obese during childhood was 4-fold higher among GDM+ children with a HEI-C score ≤70 compared to GDM+ children with a HEI-C score >70. Results of this study show that a healthy diet is associated with a better cardiometabolic health profile in GDM+ children, including a lower risk of being overweight or obese.