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This article describes the methods, successes and challenges of engaging parents while studying the impacts of COVID-19 on healthy children and families. Parent partners in a Parent and Clinician Team (PACT) informed study aims, supported feasibility and recommended changes to enhance participation. PACT members stated that they felt a sense of connectedness and purpose by contributing to COVID-19 research. Engagement increased by parents acquiring new roles, attending more frequent meetings and co-creating alternative methods of engagement. Recruiting new PACT members was challenging, likely due to limited time and resources available to parents of young children during a pandemic.

BACKGROUND International guidelines recommend children aged 9 months to 2 years consume whole (3.25%) fat cow's milk, and children older than age 2 years consume reduced (0.1-2%) fat cow's milk to prevent obesity. The objective of this study was to evaluate the longitudinal relationship between cow's milk fat (0.1-3.25%) intake and body mass index z-score (zBMI) in childhood. We hypothesized that higher cow's milk fat intake was associated with lower zBMI. METHODS A prospective cohort study of children aged 9 months to 8 years was conducted through the TARGet Kids! primary care research network. The exposure was cow's milk fat consumption (skim (0.1%), 1%, 2%, whole (3.25%)), measured by parental report. The outcome was zBMI. Height and weight were measured by trained research assistants and zBMI was determined according to WHO growth standards. A linear mixed effects model and logistic generalized estimating equations were used to determine the longitudinal association between cow's milk fat intake and child zBMI. RESULTS Among children aged 9 months to 8 years (N = 7467; 4699 of whom had repeated measures), each 1% increase in cow's milk fat consumed was associated with a 0.05 lower zBMI score (95% CI -0.07 to -0.03, p

To investigate whether social determinants of health (SDOH) are predictive of adherence to public health preventive measures and to describe changes in adherence over time among parents and children.A longitudinal study was conducted in children aged 0-10 years and their parents through the TARGet Kids! COVID-19 Study in the Greater Toronto Area, Canada (April-July 2020). This study included 335 parents (2108 observations) and 416 children (2632 observations). Parents completed weekly questionnaires on health, family functioning, socio-demographics, and public health practices. The outcome was adherence to public health preventive measures measured separately for parents and children. Marginal log-binomial models were fitted using repeated measures of the outcome and predictors.Unemployment (RR 0.67, 95% CI: 0.47, 0.97), apartment living (RR 0.72, 95% CI: 0.53, 0.99), and essential worker in the household (RR 0.74, 95% CI: 0.55, 1.00) were associated with decreased likelihood of adherence among parents; however, no associations were observed for other SDOH, including family income and ethnicity. Furthermore, there was no strong evidence that SDOH were associated with child adherence. The mean number of days/week that parents and children adhered at the start of the study was 6.45 (SD = 0.93) and 6.59 (SD = 0.86), respectively, and this decreased to 5.80 (SD = 1.12) and 5.84 (SD = 1.23) by study end. Children consistently had greater adherence than parents.SDOH were predictive of adherence to public health preventive measures among parents but less so in children among our sample of relatively affluent urban families. Adherence was high among parents and children but decreased over time. Equitable approaches to support the implementation of public health guidelines may improve adherence.RéSUMé: OBJECTIFS: Voir si les déterminants sociaux de la santé (DSS) sont des prédicteurs de conformité aux mesures de prévention sanitaire et décrire l’évolution de la conformité des parents et des enfants au fil du temps. MéTHODE: Nous avons mené une étude longitudinale auprès d’enfants de 0 à 10 ans et de leurs parents dans le cadre de l’étude sur la COVID-19 menée par le groupe de recherche TARGet Kids! dans la région du Grand Toronto, au Canada (avril à juillet 2020). L’étude incluait 335 parents (2 108 observations) et 416 enfants (2 632 observations). Les parents ont rempli un questionnaire hebdomadaire sur la santé, le fonctionnement familial, le profil sociodémographique et les pratiques sanitaires. Le résultat était la conformité aux mesures de prévention sanitaire, mesurée séparément pour les parents et les enfants. Des modèles log-binomiaux marginaux ont été ajustés à l’aide de mesures répétées du résultat et des prédicteurs. RéSULTATS: Le chômage (RR 0,67, IC de 95 % : 0,47, 0,97), la vie en appartement (RR 0,72, IC de 95 % : 0,53, 0,99) et la présence d’un travailleur essentiel dans le ménage (RR 0,74, IC de 95 % : 0,55, 1,00) étaient associés à une probabilité réduite de conformité chez les parents; par contre, aucune association n’a été observée pour les autres DSS, dont le revenu familial et l’ethnicité. Il n’y avait pas non plus d’indications convaincantes d’une association entre les DSS et la conformité chez les enfants. Le nombre moyen de jours/semaine où parents et enfants s’étaient conformés aux mesures de prévention sanitaire au début de l’étude était de 6,45 (S = 0,93) et de 6,59 (S = 0,86), respectivement; ce nombre a diminué pour atteindre 5,80 (S = 1,12) et 5,84 (S = 1,23) à la fin de l’étude. La conformité des enfants était uniformément supérieure à celle des parents. CONCLUSION: Dans notre échantillon de familles urbaines relativement aisées, les DSS étaient des prédicteurs de conformité aux mesures de prévention sanitaire chez les parents, mais dans une moindre mesure chez les enfants. La conformité était élevée chez les parents comme chez les enfants, mais elle a diminué avec le temps. Des stratégies équitables d’appui à l’application des directives sanitaires pourraient améliorer le respect de ces directives.

Infertility affects nearly 50 million couples worldwide, with 40−50% of cases having a male factor component. It is well established that nutritional status impacts reproductive development, health and function, although the exact mechanisms have not been fully elucidated. Genetic variation that affects nutrient metabolism may impact fertility through nutrigenetic mechanisms. This review summarizes current knowledge on the role of several dietary components (vitamins A, B(12), C, D, E, folate, betaine, choline, calcium, iron, caffeine, fiber, sugar, dietary fat, and gluten) in male reproductive health. Evidence of gene-nutrient interactions and their potential effect on fertility is also examined. Understanding the relationship between genetic variation, nutrition and male fertility is key to developing personalized, DNA-based dietary recommendations to enhance the fertility of men who have difficulty conceiving.

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

Background Core outcome sets (COS) are lists of consensus-determined outcomes to be measured and reported in all clinical research studies within a disease area. While including patients and families in COS development to improve their relevance and applicability to patient values is key, there is limited literature documenting practical barriers and facilitators to successful patient engagement in COS development. In this paper, as researchers and patient partners, we provide a resource for COS developers to meaningfully and effectively engage patients and families. Main body To establish a consensus-based COS for children with two inherited metabolic diseases (medium-chain acyl-CoA dehydrogenase deficiency and phenylketonuria), we conducted an evidence review, Delphi survey, and workshop. Two adult patient partner co-investigators co-developed the study protocol, co-designed strategies to address challenges with incorporating patient perspectives, and led all patient engagement activities, including communication with a group of family advisors. Seven adult family advisors received training about COS development and subsequently contributed to Delphi survey development, outcome definitions, the consensus workshop, and selection of outcome measurement instruments. Patient partner co-investigators and family advisors were essential to the successful design, conduct, and completion of the two COS. Patient partner co-investigators supported the understanding, inclusion and engagement of family advisors, and helped develop accessible tools to determine patient-oriented outcome measurement instruments. Patient partner co-investigators and family advisors collaborated with the study team to co-develop surveys, modify technical language, and recruit participants to the study. Together, we addressed challenges to patient engagement in COS development such as unfamiliarity with study methods, comprehensibility of materials and ongoing engagement, and power imbalances between team members. Conclusion Our approach to patient and family engagement in COS development for two rare conditions for children was feasible and considered valuable by all study team members, including patients and family members, in improving the relevance of the deliverable to patients. This approach to patient engagement in developing COS can be applied to other paediatric disease contexts, allowing patient and family perspectives to influence the direction of future studies to develop COS. Supplementary Information The online version contains supplementary material available at 10.1186/s40900-021-00304-y., Plain English summary Core outcome sets (COS) are lists of outcomes agreed upon by a group of people to be measured and reported in studies about certain diseases and populations. Core outcomes are meant to represent what is useful to study from the perspectives of health care providers, researchers and patients. For researchers who seek to include patients in the development of a COS, there is little guidance about how to do this well. We recently developed COS for two rare diseases in children, medium-chain acyl-CoA dehydrogenase deficiency and phenylketonuria. We did this by reviewing available information from published research, surveying health care providers, researchers, and patients, and eventually coming to agreement during a workshop. We included two adult patient partner co-researchers who helped design the COS study and co-developed the patient engagement strategy. These partners formed relationships with seven adult family advisors, who helped ensure that materials were accessible, participated in outcome selection, and helped select tools to measure core outcomes. Strategies we used to engage patient partners included a) training about both the scientific research process and how to help other researchers in the future, and b) frequent communication about study progress and how family advisor feedback was used. Also, we made sure that the impacts of power imbalances between health care providers, researchers and patients were low. Our approach to patient engagement in COS development for two rare conditions in children proved to be both feasible and considered valuable by all study team members, including patient partners and family advisors. To include patient perspectives and values, future COS developers may take a similar approach. Supplementary Information The online version contains supplementary material available at 10.1186/s40900-021-00304-y.

Background The COVID-19 pandemic has uniquely affected children and families by disrupting routines, changing relationships and roles, and altering usual child care, school and recreational activities. Understanding the way families experience these changes from parents’ perspectives may help to guide research on the effects of COVID-19 among children. Main body As a multidisciplinary team of child health researchers, we assembled a group of nine parents to identify concerns, raise questions, and voice perspectives to inform COVID-19 research for children and families. Parents provided a range of insightful perspectives, ideas for research questions, and reflections on their experiences during the pandemic. Conclusion Including parents as partners in early stages of COVID-19 research helped determine priorities, led to more feasible data collection methods, and hopefully has improved the relevance, applicability and value of research findings to parents and children.

Objective To evaluate the relationship between the timing of infant cereal introduction between 4 and 6 months of age and growth and dietary intake in later childhood. Study design A longitudinal cohort study was conducted among healthy children 0-10 years of age participating in The Applied Research Group for Kids cohort study between June 2008 and August 2019 in Toronto, Canada. Results Of 8943 children included, the mean (SD) age of infant cereal introduction was 5.7 (2.1) months. In the primary analysis, children who were introduced to infant cereal at 4 vs 6 months had 0.17 greater body mass index z score (95% CI 0.06-0.28; P = .002) and greater odds of obesity (OR 1.82; 95% CI 1.18-2.80; P = .006) at 10 years of age. In the secondary analysis, children who were introduced to infant cereal at 4 vs 6 months had 0.09 greater height-for-age z score (95% CI 0.04-0.15; P = .002) at 1 year of age, an association that was not observed at 5 or 10 years of age. Children who were introduced to infant cereal at 4 vs 6 months had greater nutrition risk which was primarily determined by a less-favorable eating behavior score at 18 months to 5 years of age (0.18 units higher; 95% CI 0.07-0.29; P = .001). Conclusions Introduction of infant cereal at 4 vs 6 months was associated with greater body mass index z score, greater odds of obesity, similar height-for-age z score, and less favorable eating behavior. These findings support recommendations for introducing solid food around 6 months of age.

Primary Subject area Public Health and Preventive Medicine Background Various studies have examined the general impact of the COVID-19 outbreak on children’s health behaviours. The impact of public health measures practised by children during COVID-19 is relatively unknown. Objectives The primary objective was to determine the association between physical and social distancing measures and children’s outdoor time, sleep duration, and screen time during COVID-19. Design/Methods A longitudinal study using repeated measures of exposures and outcomes was conducted in healthy children (0 to 10 years) between April 14 and July 15, 2020. Parents were asked to complete questionnaires about isolation, physical distancing practices, and children’s health behaviours. The primary exposure was the average number of days that children practised physical and social distancing measures per week. The three outcomes were children’s outdoor time, total screen time, and sleep duration during COVID-19. Linear mixed effects models were fitted using repeated measures of primary exposure and outcomes. Results This study included 554 observations from 265 children. Physical and social distancing measures were associated with shorter outdoor time (-17.2; 95% CI -22.07, -12.40; p < 0.001) and longer total screen time (11.3; 95% CI 3.88, 18.79; p = 0.003) during COVID-19. The association with outdoor time was stronger in younger children (< 5 years), and the associations with total screen time were stronger in females and in older children (≥ 5 years). Conclusion Physical and social distancing measures during COVID-19 have resulted in negative impacts on the health behaviours of Canadian children living in a large metropolitan area.

The primary objective was to determine the association between public health preventive measures and children's outdoor time, sleep duration, and screen time during COVID-19.A cohort study using repeated measures of exposures and outcomes was conducted in healthy children (0 to 10 years) through The Applied Research Group for Kids (TARGet Kids!) COVID-19 Study of Children and Families in Toronto, Canada, between April 14 and July 15, 2020. Parents were asked to complete questionnaires about adherence to public health measures and children's health behaviours. The primary exposure was the average number of days that children practiced public health preventive measures per week. The three outcomes were children's outdoor time, total screen time, and sleep duration during COVID-19. Linear mixed-effects models were fitted using repeated measures of primary exposure and outcomes.This study included 554 observations from 265 children. The mean age of participants was 5.5 years, 47.5% were female and 71.6% had mothers of European ethnicity. Public health preventive measures were associated with shorter outdoor time (-17.2; 95% CI -22.07, -12.40; p0.001) and longer total screen time (11.3; 95% CI 3.88, 18.79; p = 0.003) during COVID-19. The association with outdoor time was stronger in younger children (5 years), and the associations with total screen time were stronger in females and in older children (≥5 years).Public health preventive measures during COVID-19 were associated with a negative impact on the health behaviours of Canadian children living in a large metropolitan area.RéSUMé: OBJECTIF: L’objectif principal était de déterminer la relation entre les mesures préventives de la santé publique et le temps passé en plein air, la durée du sommeil ainsi que le temps passé devant l’écran par les enfants pendant COVID-19. MéTHODES: Une étude de cohorte utilisant des mesures répétées des expositions et des effets a été menée chez des enfants en bonne santé (0 à 10 ans) par l’entremise de l’Étude COVID-19 sur les Enfants et Familles du Groupe de Recherche Appliquée pour les Enfants (TARGet Kids!) à Toronto, au Canada, entre le 14 avril et le 15 juillet 2020. Les parents ont été invités à remplir des questionnaires sur adhésion aux mesures préventives de la santé publique et les comportements de santé des enfants. La principale exposition était le nombre moyen de jours par semaine durant lesquels les enfants pratiquaient des mesures préventives de la santé publique. Les trois effets étaient le temps passé en plein air par les enfants, le temps total passé devant l’écran et la durée du sommeil pendant le COVID-19. Des modèles linéaires à effets mixtes ont été ajustés en utilisant des mesures répétées d’exposition primaire et des effets. RéSULTATS: Cette étude comprend 554 observations sur 265 enfants. L’âge moyen des participants était de 5,5 ans, 47,5 % étaient des femmes et 71,6 % avaient des mères d’origine européenne. Les mesures préventives de la santé publique ont été associées à un temps passé en plein air plus court (-17,2 ; IC 95% -22,07, -12,40; p0,001) et à un temps total devant l’écran plus long (11,3 ; IC 95% 3,88, 18,79; p = 0,003) pendant la COVID-19. La relation avec le temps passé en plein air était plus importante chez les jeunes enfants (5 ans), et les relations avec le temps total passé devant l’écran étaient plus importantes chez les enfants de sexe féminin et les enfants plus âgés (≥5 ans). CONCLUSION: Les mesures préventives de la santé publique prises lors de COVID-19 ont été associées à un impact négatif sur les comportements de santé des enfants canadiens vivant dans une grande région métropolitaine.

Background International guidelines recommend that children older than 2 years of age consume reduced fat (0.1-2%) instead of whole cow’s milk (3.25% fat) to prevent childhood obesity, but these guidelines are consensus-based and have a low GRADE level of evidence. Objectives The primary objective of this study was to evaluate the longitudinal relationship between cow’s milk fat (0.1-3.25%) intake and Body Mass Index z-score (zBMI) in children aged 9 months to 8 years. The secondary objective was to determine the relationship between cow’s milk fat intake and odds of overweight (zBMI >1) and obesity (zBMI > 2). Design/Methods A prospective cohort study of children 9 months to 8 years of age was conducted through the TARGet Kids! primary care research network. The primary exposure was cow’s milk fat consumption (skim (0.1%), 1%, 2%, or whole [3.25%]), measured by parental report. The primary outcome was zBMI, an age and sex adjusted measure of child adiposity. Height and weight were measured by trained research assistants and zBMI was determined according to the WHO growth standards. A linear mixed effects model and logistic generalized estimating equations were used to determine the longitudinal association between cow’s milk fat intake and child zBMI. Results Among children aged 9 months to 8 years of age (N= 7467), each 1% increase in cow’s milk fat consumed was associated with a 0.05 lower zBMI score (95% CI -0.07 to -0.03, p< 0.0001). Compared to children who consumed reduced fat (0.1-2%) cow’s milk, there was evidence that children who consumed whole cow’s milk had 16% lower odds of overweight (OR=0.84, 95% CI 0.77 to 0.91), p< 0.0001) and 18% lower odds of obesity (OR= 0.82, 95% CI 0.68 to 1.00, p= 0.047). Conclusion Guidelines for reduced fat instead of whole cow’s milk during childhood may not be effective in preventing overweight or obesity. Randomized controlled trial data is needed to understand which cow’s milk fat optimizes child growth, development and nutrition.

International guidelines recommend children aged 9 months to 2 years consume whole (3.25%) fat cow's milk, and children older than age 2 years consume reduced (0.1-2%) fat cow's milk to prevent obesity. The objective of this study was to evaluate the longitudinal relationship between cow's milk fat (0.1-3.25%) intake and body mass index z-score (zBMI) in childhood. We hypothesized that higher cow's milk fat intake was associated with lower zBMI.A prospective cohort study of children aged 9 months to 8 years was conducted through the TARGet Kids! primary care research network. The exposure was cow's milk fat consumption (skim (0.1%), 1%, 2%, whole (3.25%)), measured by parental report. The outcome was zBMI. Height and weight were measured by trained research assistants and zBMI was determined according to WHO growth standards. A linear mixed effects model and logistic generalized estimating equations were used to determine the longitudinal association between cow's milk fat intake and child zBMI.Among children aged 9 months to 8 years (N = 7467; 4699 of whom had repeated measures), each 1% increase in cow's milk fat consumed was associated with a 0.05 lower zBMI score (95% CI -0.07 to -0.03, p 0.0001) after adjustment for covariates including volume of milk consumed. Compared to children who consumed reduced fat (0.1-2%) milk, there was evidence that children who consumed whole milk had 16% lower odds of overweight (OR = 0.84, 95% CI 0.77 to 0.91, p 0.0001) and 18% lower odds of obesity (OR = 0.82, 95% CI 0.68 to 1.00, p = 0.047).Guidelines for reduced fat instead of whole cow's milk during childhood may not be effective in preventing overweight or obesity.

Objective:Consensus guidelines recommend that children consume reduced-fat (0·1–2 %) cow’s milk at age 2 years to reduce the risk of obesity. Behaviours and perspectives of parents and physicians about cow’s milk fat for children are unknown. Objectives were to: (i) understand what cow’s milk fat recommendations physicians provide to 2-year-old children; (ii) assess the acceptability of reduced-fat v. whole cow’s milk in children’s diets by parents and physicians; and (iii) explore attitudes and perceptions about cow’s milk fat for children.Design:Online questionnaires and individual interviews were conducted. Questionnaire data were analysed using descriptive statistics. Interview transcripts were analysed using a general inductive approach and thematic analysis.Setting:The TARGet Kids! practice-based research network in Toronto, Canada.Participants:Questionnaire respondents included fifty parents and fifteen physicians; individual interviews were conducted with with fourteen parents and twelve physicians.Results:Physicians provided various milk fat recommendations for 2-year-old children. Parents also provided different cow’s milks: eighteen (36 %) provided whole milk and twenty-nine (58 %) provided reduced-fat milk. Analysis of qualitative interviews revealed three themes: (i) healthy eating behaviours, (ii) trustworthy nutrition information and (iii) importance of dietary fat for children.Conclusions:Parents provide, and physicians recommend, a variety of cow’s milks for children and hold mixed interpretations of the role of cow’s milk fat in children’s diets. Clarity about its effect on child adiposity is needed to help make informed decisions about cow’s milk fat for children.

BACKGROUND: Childhood obesity has tripled in the past 40 years with nearly 1 in 3 children in Canada now overweight or obese. Over the same period, consumption of whole cow’s milk has halved. Health Canada recommends that children switch from whole fat cow’s milk (3.25%) to reduced fat cow’s milk (0.1 to 2%) at 2 years of age to limit fat intake and minimize the risk of childhood obesity. Given that cow’s milk is consumed daily by most children in Canada and is a major dietary source of energy, protein and fat, understanding the relationship between cow’s milk fat and risk of overweight or obesity is important. To our knowledge, no systematic review or meta-analysis has evaluated the relationship between cow’s milk fat consumption and childhood adiposity. OBJECTIVES: The primary objective of this study was to evaluate the relationship of whole fat (3.25%) compared to reduced fat (0.1 to 2%) cow’s milk and adiposity in children aged 1 to 18 years among existing literature. DESIGN/METHODS: A systematic review and meta-analysis was conducted. Data sources included EMBASE, CINAHL, Medline, SCOPUS, and Cochrane Library databases from inception to March 2018. Inclusion criteria were observational and interventional studies of healthy children aged 1–18 years which evaluated the association between cow’s milk fat consumption and child adiposity. Risk of bias and study quality was assessed using the Newcastle Ottawa Scale; methodological characteristics and results were summarized. A meta-analysis was conducted using a random effects model to evaluate the relationship between cow’s milk fat consumption and overall risk of childhood overweight or obesity. RESULTS: Inclusion criteria were met by 18 cross-sectional studies, 9 prospective cohort studies and no interventional studies. Overall, 16 of 27 studies found that higher cow’s milk fat was associated with lower adiposity, 1 study found that higher cow’s milk fat was associated with higher adiposity, and 10 studies did not identify an association. Meta-analysis using pooled data from 12 studies (N=20,171) with data on the proportion of children who consumed whole vs. reduced fat milk as well as direct measures of overweight or obesity identified that cow’s milk fat was associated with lower risk of childhood overweight or obesity (p

BACKGROUND Fortified cow milk is a material contributor of vitamin D and dietary fat in children. Recommendations for children >2 y of age advise reduced milk-fat consumption to reduce childhood obesity, yet the relation between lower milk fat, vitamin D stores, and body mass index (BMI) is unclear. OBJECTIVES The primary objective was to explore the association between milk-fat percentage and both BMI z score (zBMI) and venous 25-hydroxyvitamin D [25(OH)D]; the secondary objective was to assess whether milk volume consumed modified this relation. DESIGN This was a cross-sectional analysis. Healthy urban children aged 12-72 mo were recruited from 9 primary health care practices within The Applied Research Group for Kids (TARGet Kids!) research group in Toronto, Canada. We used adjusted bivariate linear regression to examine the relation between milk-fat percentage and child 25(OH)D and zBMI concurrently. Effect modification by milk volume consumed on the evaluated relations was explored with the use of an interaction term in the statistical model. RESULTS Among the 2745 included children there was a positive association between milk-fat percentage and 25(OH)D (P = 0.006) and a negative association between milk-fat percentage and zBMI (P < 0.0001). Participants who drank whole milk had a 5.4-nmol/L (95% CI: 4.32, 6.54) higher median 25(OH)D concentration and a 0.72 lower (95% CI: 0.68, 0.76) zBMI score than children who drank 1% milk. Milk volume consumed modified the effect of milk-fat percentage on 25(OH)D (P = 0.003) but not on zBMI (P = 0.77). CONCLUSIONS Whole milk consumption among healthy young children was associated with higher vitamin D stores and lower BMI. Longitudinal and interventional studies are needed to confirm these findings. TARGet Kids! was registered at clinicaltrials.gov as NCT01869530.

IntroductionCow’s milk is a dietary staple for children in North America. Though clinical guidelines suggest children transition from whole (3.25% fat) milk to reduced (1% or 2%) fat milk at age 2 years, recent epidemiological evidence supports a link between whole milk consumption and lower adiposity in children. The purpose of this trial is to determine which milk fat recommendation minimises excess adiposity and optimises child nutrition and growth.Methods and analysisCow’s Milk Fat Obesity pRevention Trial will be a pragmatic, superiority, parallel group randomised controlled trial involving children receiving routine healthcare aged 2 to 4–5 years who are participating in the TARGet Kids! practice-based research network in Toronto, Canada. Children (n=534) will be randomised to receive one of two interventions: (1) a recommendation to consume whole milk or (2) a recommendation to consume reduced (1%) fat milk. The primary outcome is adiposity measured by body mass index z-score and waist circumference z-score; secondary outcomes will be cognitive development (using the Ages and Stages Questionnaire), vitamin D stores, cardiometabolic health (glucose, high-sensitivity C-reactive protein, non-high density lipoprotein (non-HDL), low density lipoprotein (LDL), triglyceride, HDL and total cholesterol, insulin and diastolic and systolic blood pressure), sugary beverage and total energy intake (measured by 24 hours dietary recall) and cost effectiveness. Outcomes will be measured 24 months postrandomisation and compared using analysis of covariance (ANCOVA), adjusting for baseline measures.Ethics and disseminationEthics approval has been obtained from Unity Health Toronto and The Hospital for Sick Children. Results will be presented locally, nationally and internationally and published in a peer-reviewed journal. The findings may be helpful to nutrition guidelines for children in effort to reduce childhood obesity using a simple, inexpensive and scalable cow’s milk fat intervention.Trial registration numberNCT03914807; pre-results.

BACKGROUND: Since 1992, Health Canada has recommended that children switch from whole fat cow’s milk (3.25%) to reduced fat cow’s milk (1–2%) at age 2 years to reduce risk of obesity. Despite this, observational evidence has consistently shown that children who consume whole cow’s milk have lower measures of adiposity and risk of overweight/obesity. Intervention research is needed to understand the causal relationship between cow’s milk fat and adiposity in childhood. While traditional randomized controlled trials (RCTs) are time consuming, costly, and require many resources, usual care research within existing research cohorts may be a promising way to minimize necessary resources and expedite large, representative RCTs. However, usual care practices and perspectives on cow’s milk fat among physicians and parents are unknown. OBJECTIVES: The objectives of this study were to first understand cow’s milk fat practice among physicians and parents, and assess the acceptability of a recommendation for whole milk. Next, we aimed to use these results to design the CoMFORT trial, which will evaluate the effect of cow’s milk fat on child adiposity. DESIGN/METHODS: This study took place within the TARGet Kids! primary care research network. We conducted online questionnaires through SurveyMonkey (surveymonkey.com), followed by in-depth interviews with primary care physicians, and parents of children aged 2–5 years who drink milk. Questionnaire data was analyzed using descriptive statistics; interviews were recorded, transcribed and analyzed using a general inductive approach and thematic analysis. Themes relevant to our objectives were identified and described to capture core messages from both physicians and parents. Physician and parent experiences and views were reviewed by the study team to create a framework for the CoMFORT protocol, identify barriers and facilitators to the CoMFORT intervention, and inform strategies for maximizing trial enrolment and adherence. RESULTS: Online surveys were completed by 50 parents and 15 physicians. In-depth interviews were conducted with 14 parents and 12 physicians. At the 2-year well-child visit, 29% of physicians usually recommended reduced fat (2%) milk, 36% recommended whole fat (3.25%) milk, and 36% made no milk fat recommendation. Among parents, 62% currently provided reduced fat (0.1–2%) milk, and 38% provided whole fat (3.25%) milk to their children. Overall, physicians and parents were willing to provide whole fat milk to children over age 2 years. Thematic analysis identified three themes: trust, in evidence among physicians and in physicians among parents; fat, and its role in a child’s diet; and healthy food – what it is, and how identity interacts with the provision of healthy food. Parent and physician usual practice, and attitudes and perceptions about cow’s milk fat, confirmed the feasibility and need for a usual care RCT. CONCLUSION: These findings allowed us to understand physician and parent decision making practices, attitudes towards cow’s milk fat in children’s diets, and factors that would encourage or limit adherence to the CoMFORT trial protocol. The CoMFORT trial will inform international guidelines for cow’s milk consumption in childhood and positively impact child growth and development.

Current guidelines for cow’s milk consumption in children older than age 2 years suggest 1% or 2% milk to reduce the risk of obesity. Given that milk is the main dietary source of vitamin D for North American children and that vitamin D is fat soluble, we hypothesized 25-hydroxyvitamin D (25(OH)D) concentration to be positively associated with the fat content of milk. The objective was to determine the relationship between the fat content of milk consumed and the serum 25(OH)D concentration; our secondary objective was to explore the role that the volume of milk consumed played in this relationship. We completed a cross-sectional study of children aged 12–72 months in the TARGetKids! research network. Multivariable linear regression was used to test the association between milk fat content and child 25(OH)D, adjusted for clinically relevant covariates. The interaction between volume of milk and fat content was examined. Two thousand eight hundred fifty-seven children were included in the analysis. The fat content of milk was positively associated with 25(OH)D (p = 0.03), and the interaction between the volume of milk consumed and the milk fat content was statistically significant (p = 0.005). Children who drank 1% milk needed 2.46 cups (95% confidence interval (CI) 2.38–2.54) of milk to have a 25(OH)D concentration similar to that of children who drank 1 cup of homogenized milk (3.25% fat). Children who consumed 1% milk had 2.05 (95% CI 1.73–2.42) times higher odds of having a 25(OH)D concentration