Bone Health in Children and Adolescents: The Role of Dairy as part of a Healthy Diet

There is consistent evidence supporting the role of milk and milk products as part of a healthy diet for the development of strong and healthy bones in children and adolescents, a key strategy for preventing osteoporosis and fractures in older age.

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Highlights

  • Childhood and adolescence are key periods for achieving optimal bone health including peak bone mass which is critical for preventing osteoporosis and fractures later in life.
  • Certain modifiable factors have been associated with better bone health in children and adolescents, such as weight-bearing strength training, and a healthy diet.
  • Dairy products, including milk, cheese, and yogurt, have been associated with improved bone health.
  • Calcium and vitamin D, key components in bone metabolism, have been associated with higher bone density.
  • Milk and milk products are important sources of calcium and vitamin D.

Basic facts on bone health in children and adolescents

Childhood and adolescence are critical periods for achieving optimal musculoskeletal health in adulthood; bone tissue accreted during these years will help both ensure normal skeletal growth and increase bone strength.1,2,3 Beyond reducing fracture risk in young age, childhood bone mass is also predictive of osteoporosis risk in adulthood.1,3 In fact, maximizing peak bone mass by young adulthood is considered a key primary strategy for preventing osteoporotic fracture risk in later years.1,3

Certain modifiable factors have been associated with better bone health in children and adolescents, such as weight-bearing strength training, and a healthy diet that meets energy requirements and includes adequate amounts of micronutrients to support growth and development.2,3,4 Namely, calcium, vitamin D, and protein are frequently identified as key nutrients in the development of healthy bones, although a wide range of nutrients are involved in musculoskeletal development (such as iron, zinc, magnesium, and vitamin K).2,3,4 Increases in peak bone mass as small as 5-10% achieved by young adulthood have been associated with a decrease future hip fracture risk of up to 50%, thus highlighting the importance of adopting bone-healthy behaviours.3 

The evidence

In their 2016 position statement, based on their systematic review of the evidence, the National Osteoporosis Foundation graded the evidence for dairy consumption and peak bone mass development as good.1

A 2020 systematic review compiled the findings of original studies (both observational and experimental studies) on bone health and dairy throughout the lifecycle.3 While study authors underscore the need for more research to strengthen the level of evidence for children and adolescents, 8 out of 10 included randomized controlled trials (RCTs) in this age group linked dairy consumption to improvements in parameters of bone health, with none showing detrimental effects.3

A 2019 review of systematic reviews and meta-analyses describing 19 original studies  (RCTs and observational studies) highlighted the benefits of dairy on bone health in children and adolescents.4 

  • This review found an association between the consumption of dairy products and increased total body bone mineral content in children and adolescents, particularly in those with low baseline calcium intakes. 
  • Moreover, the increase in bone mineral content attributed to dairy was comparable to that of physical exercise. 

In a systematic review of clinical trials including a total of 2,032 children (18 years or younger), dairy intake was linked to improved bone health.5 

  • In healthy children between 10 and 17 years old, bone mineral density increased by 8% after 16 months of regular consumption of milk, cheese, and yogurt which provided 1000 milligrams of calcium per day.5
  • In this study, authors noted that 11 out of the 14 original studies that were included observed benefits of dairy consumption on measures of bone health.5 

A meta-analysis of 21 randomized controlled trials of 3,821 children aged 4 to 17 years assessed the impact of milk products and dietary calcium on bone mass.6

  • In studies conducted on children with low calcium intakes at baseline, milk product consumption or calcium supplements increased total body and lumbar spine bone mineral content.6

A 12-week randomized controlled trial by Josse et al. (2020) found that the inclusion of 3-4 portions per day of milk products (milk, cheese, and yogurt) combined with regular physical activity decreased markers of bone resorption in overweight or obese teenage girls, when compared to physical activity alone.7 

  • Considering the participants’ low baseline consumption of dairy foods, the researchers recommend that this level of dairy consumption (3-4 portions of milk products per day) be encouraged in this age group.7

Potential mechanisms

Calcium and vitamin D are the two main nutrients of interest for achieving optimal bone health.8 Both the Canadian Pediatrics Society and the American Academy Pediatrics recommend including foods rich in calcium and vitamin D for the development and maintenance of strong bones during childhood and adolescence.9,10 Milk and milk products are a major source of calcium and vitamin D in the diet of Canadians.11,12  

Calcium

Calcium is critical to maintaining skeletal metabolism due to its central role in providing the bone structure and rigidity.8

In their 2016 position statement, the National Osteoporosis Foundation qualified the evidence supporting the benefits of dietary calcium on bone health in children as strong.1

Calcium is a nutrient of concern for many Canadian children. A comparison of the calcium intakes of Canadians between the 2004 and 2015 Canadian Community Health Survey (CCHS) cycles revealed high rates of calcium inadequacy in children:13 

  • In Canadian children (1-8 years), calcium inadequacy rates were 42.1% and 28.6% in supplement nonusers and users, respectively;13
  • In children who did not consume calcium supplements, over 81.5% of Canadian girls (9-18 years) and 66% of boys (9-18 years) did not reach their dietary recommendations for calcium;13
  • An increase in the rate of calcium inadequacy was observed in 2015 in all age groups for Canadian children (1-18 years) when compared to 2004;13 
  • Overall calcium intakes have decreased between 2004 and 2015, which the authors attributed to a reduced consumption of milk and alternatives.13 However, milk and alternatives continue to be the major contributor of calcium in the diet.

A 2018 longitudinal cohort study compared dietary calcium intakes of 179 children over 3 years at ages 4, 5, and 6 years to their bone mineral density until the age of 7 years:14

  • In children who met over 95% of their calcium requirements for two or three consecutive years, whole body bone mineral density was increased, and a lower risk of osteopenia was observed;
  • Researchers also found that an increase of 100 mg of calcium per day increased bone mineral density of lumbar spine z-score by 0.1. 

Vitamin D

Vitamin D is a fat-soluble vitamin that supports the intestinal absorption of calcium.8 

In their 2016 position statement, the National Osteoporosis Foundation qualified the evidence supporting the benefits of dietary vitamin D on bone health in children as good.1 

A 12-month prospective case-control study compared the vitamin D status of children who had experienced a fracture to that of children who did not have a fracture:15

  • In children aged between 2 and 14 years, low vitamin D status was linked to a higher risk of fractures.15 

A study of the 2013 Canadian Health Measures Survey found that only 68% of Canadian children had sufficient levels of vitamin D in their blood.16  

  • Importantly, vitamin D sufficiency rates decreased between 2007 and 2013, which the authors attributed in part to a decreased consumption of dairy milk, which was the main source of dietary vitamin D.16  

Further evidence supports that Canadian children may not be consuming enough vitamin D to meet their requirements, with dairy products, particularly milk, being the main source of vitamin D in the Canadian diet.17 

Conclusion

During childhood and adolescence, a healthy diet rich in key nutrients, such as calcium and vitamin D, may contribute to the development of good bone health. Milk products are an important source of calcium and vitamin D. Ensuring optimal bone health during developmental years may not only yield benefits during this time, but it may also be protective against osteoporosis and fragility fractures in adulthood.

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