Completed Studies

Adding vitamin D to non-cow’s milk beverages (soy, rice, oat, almond, etc.) is optional, but required for cow’s milk, in North America. The effect of drinking non-cow’s milk beverages on blood vitamin D levels in children is unclear. The goal of this study was to see how drinking non-cow’s milk beverages related to vitamin D levels in preschool-aged children and included 2,831 children 1-6 years of age. Parents were asked to report the number of cups of non-cow’s milk their child consumed per day, and children’s blood samples were measured for vitamin D levels. Children that drank non-cow’s milk beverages had lower vitamin D levels than children who drank cow’s milk. Children who only drank non-cow’s milk had a higher risk of having vitamin D levels below the recommended lower limit than children who drank only cow’s milk. The results suggest that parents may consider choosing non-cow’s milk beverages with added vitamin D if they provide them to children, or providing other sources of vitamin D such as a supplement.

Cow’s milk consumption in childhood has been linked to taller height. Some parents are choosing non-cow milk beverages (soy, rice, oat, almond, etc.) due to perceived health benefits. The goal of this study was to see how drinking non-cow’s milk beverages related to height in childhood. This study included 5,034 children aged 2-6 years. Parents were asked how much non-cow’s milk beverages their children consumed per day and children’s height was measured at physician’s offices. Children who drank non-cow’s milk had shorter height than children who drank cow’s milk. Future studies are needed to understand key nutrients or mechanisms driving this relationship.  

In developed countries, iron deficiency and overweight/obesity are common nutrition-related disorders in young children. In young children, not much is known about the relationship between obesity and iron deficiency. The goal of this research was to see if body mass index (BMI), which is a measure of weight status, was related to iron deficiency in early childhood. This study included 1,607 children aged 1-3 years.  Height and weight were measured for each child at physician’s offices. Blood samples were taken from each child and iron levels were measured. Children with a higher BMI had lower iron levels in their blood and increased risk of iron deficiency. These results suggest that BMI could be used as a risk factor for targeted screening of iron deficiency in young children.

More time spent watching TV is associated with language delays in early childhood. Children now have access to not only television but smartphones and tablets (mobile media devices), which could increase the amount of time they spend looking at a screen. The goal of this study was to see if using mobile media devices was associated with communication delays in 18-month-old children. Parents of 893 children were asked how much time their child spent using mobile media devices per day. Research staff measured expressive speech delay and other communication delays in each child. Increased daily mobile media device use was associated with higher risk of expressive speech delay, but not with other communication delays. These results show why it is important for parents to monitor and, when necessary, limit the amount of time young children spend on mobile media devices.

Outdoor free play is important for child physical activity, health and development. Certain temperaments (a way of describing a child’s mood and emotional tendencies) have been linked to obesity, nutrition and sedentary behaviour. The goal of this study was to see if there was a relationship between temperament and outdoor play in young children. This study included 3,393 children 1-5 years old. Child temperament and outdoor free play were assessed through parent completed questionnaires. Boys with higher negative affectivity (more angry or distressed moods and emotions) spent less time playing outside per day, but not girls. Children that were more extroverted (enjoyed spending time with others and socializing) spent on average more time playing outside. In the future, interventions and strategies that consider child temperament may be better at increasing outdoor play in young children.

Cardiometabolic risk describes a person’s chance of having diabetes, heart disease or stroke. Cardiometabolic risk can be expressed as a score, which considers values such as blood pressure and blood cholesterol. In this study, we analyzed the relationship between the number of hours young children slept per 24 hours and cardiometabolic risk score. We included daily sleep time, in hours, from 597 children aged 12-36 months. Participants later provided blood samples which were used to calculate cardiometabolic risk scores. No links were found between duration of sleep and cardiometabolic risk score, but children who slept fewer hours tended to have slightly higher HDL "good" cholesterol. More research is needed in this area.  

Canadian nutrition guidelines recommend that infants aged 6 to 24 months eat iron-rich foods such as meat and meat alternatives at least twice a day. To test whether this recommendation prevents iron deficiency, we had parents answer questions on their infants’ meat and meat alternatives consumption and compared that to the infants’ blood ferritin, which indicates iron stores. We collected data from 1043 infants aged 12 to 36 months and found no link between consumption of red meat and blood ferritin level, but higher meat and meat alternative consumption did reduce the risk of iron deficiency among children. Eating meat and meat alternatives according to Canadian recommendations may be a promising target to prevent iron deficiency in early childhood.

Milk consumption is often promoted as a way for children to grow strong and healthy bones by providing vitamin D, but too much milk may reduce the body’s iron stores. We recruited 1311 children aged 2 to 5 years who provided blood samples and dietary intake information. Children who consumed two cups of milk per day were able to maintain healthy blood iron and vitamin D levels, but children with darker skin were more likely to have low vitamin D blood levels in the winter if they drank this amount without taking a vitamin D supplement. Therefore, consuming 2 cups of cow’s milk is a good target for children to maintain healthy levels of both vitamin D and iron, and children with darker skin pigmentation should supplement with vitamin D in wintertime.

Vitamin D is known to play an important role in maintaining bone health, so we investigated whether children with bone fractures had lower blood levels of vitamin D compared to children without bone fractures. We recruited children under 6 years old- 206 who had fractures and 343 who didn’t- and examined their blood for vitamin D levels. Their parents also reported how much cow's milk, which contains vitamin D, the children typically drank and whether they took vitamin D supplements. No link was found between having a bone fracture and blood levels of vitamin D, or the amount of milk consumed. Children who took vitamin D supplements were less likely to experience a bone fracture. We concluded that vitamin D supplementation may help prevent bone fractures in young children.

Because having overweight or obesity has been linked to health complications, we observed whether children who had higher weights in preschool years used mental health services in later childhood. We used electronic medical records to identify 10, 522 children whose height and weight were recorded between 2 and 5 years of age, and observed whether they started using a mental health service between 5 to 19 years of age.  We found that girls with obesity in early childhood were 2.73 times more likely to use mental health services in later childhood compared to girls with healthy weight; this figure was 1.22 for boys with borderline overweight and 1.43 for boys with overweight in comparison to boys with healthy weight. In summary, we found a link between having higher-than-healthy weight in preschool and using mental health services in later childhood.