82% of teen girls and 44% of teen boys don’t get enough calcium for healthy bones

While most Australian children consume enough calcium during early childhood, calcium consumption is insufficient in more than half of Australian 12-16 year olds. Young females are most likely to be calcium deficient.

Calcium is an essential nutrient for healthy teeth and bones and adequate consumption during childhood and adolescence is essential for a lifetime of healthy bones. "Calcium is the most important building block for bones. You need to build strong bones when you’re young to protect against fracture later in life. Calcium is the nutrient most likely to be deficient in your diet for good bone health," said Professor Connie Weaver, Head of Department of Food and Nutrition, Purdue University.

Findings of the recently published Australian National Children’s Survey of Nutrition and Physical Activity, show that only 11% of 12-13 year old girls and 18% of 14-16 year old girls consume enough calcium. While a higher proportion of 12-16 year old boys consume adequate calcium, only approximately half consume the estimated average requirement of the National Health and Medical Research Council.

Professor Weaver says she was shocked by the survey results. The inadequate consumption of calcium amongst Australian children is "setting the stage for a huge problem of osteoporosis later in life and can increase the risk of childhood fractures," said Prof Weaver.

Calcium intake in the early years of adolescence is extremely important, as this is the period in which bone mass increases most rapidly. Once a child finishes growing, calcium consumption does not increase bone mass. The calcium consumed by adults only maintains existing bone mass (i.e. the bone mass developed during childhood and adolescence).

During the pubertal growth spurt, bone mass increases three-fold. Girls develop more than a quarter of their adult peak bone mass between the ages 12-14, and boys between ages 13-15. Adequate nutrition during adolescence, in particular consumption of sufficient calcium, is therefore extremely important.

"You build most of your adult bone during the pubertal growth spurt. After adolescence you have passed the window of opportunity to build bone. So then the best you can do is to prevent further loss," Professor Weaver said.

Consuming dairy products with every meal is the best way to ensure adequate calcium intake and the development of healthy bones. By ensuring a child consume three servings of dairy products a day (and four during adolescence), parents can ensure their children consume enough calcium to develop healthy bones. "If you think about a calcium rich source with every meal, like a glass of milk or a cup of yoghurt, it’s not difficult to get enough calcium," said Professor Weaver.

However people who avoid dairy products, may find it difficult to consume enough calcium. While many vegetables contain calcium, the calcium they contain is less readily absorbed by the body than the calcium contained in milk. You would also have to consume very large quantities of vegetables to get the same quantity of calcium contained in a serve of dairy.

Prof Weaver recommends that people who are intolerant to, or dislike consuming dairy, should take calcium supplements or eat calcium fortified foods to ensure adequate consumption. However she emphasised that supplements do not provide all the benefits of dairy calcium.

While adequate calcium intake can be achieved by using calcium supplements, supplements lack many of the additional nutrients contained in dairy products (e.g. magnesium) which also promote bone health. Prof Weaver’s research suggests that consumption of dairy products is better for building healthy bones than calcium supplements.

"We don’t know what gives the advantages of dairy, but when I feed rats dairy compared to calcium carbonate the bones become larger, stronger and more resistant to breaking," said Professor Weaver.

As many individuals, and particularly adolescent girls may be wary of consuming dairy products due to their high fat content, Prof Weaver also emphasised that adequate dairy consumption does not equal a high fat diet.  "Adolescent girls around the world tend not to consume enough dairy products, partly because they are worried about their weight," said Professor Weaver. "However adequate dairy consumption is not associated with weight gain. If you are concerned about your weight, you might want to choose the low fat and low sugar versions of dairy products."

References

1. Commonwealth Scientific and Industrial Research Organisation, 2007 Australian National Children’s Nutrition and Physical Activity Survey: Main Findings, Commonwealth of Australia, 2008, available from: http://www.health.gov.au/internet/main/publishing.nsf/Content/66596E8FC68FD1A3CA2574D50027DB86/$File/childrens-nut-phys-survey.pdf
2. National Health and Medical Research Council, Nutrient Reference Values for Australia and New Zealand (including recommended dietary intakes)- Calcium, National Health and Medical Research Council and New Zealand Ministry of Health, 2006, available from: http://www.nrv.gov.au/_resources/n35-calcium.pdf
3. Weaver, C.M. "The role of nutrition in optimising peak bone mass" in Asia Pac J Clin Nut, 2008, 17(Supp 1):135-7.
4. Weaver, C.M. Prolux, W.R. Heaney, R. "Choices for achieving adequate dietary calcium with a vegetarian diet" in Am J Clin Nut,  1999, 70(3):543S-548S.
5. Weaver, C.M. "Calcium bioavailability and its relation to osteoporosis" in Proc Soc Exp Biology Med, 1992, 200:157-160.
6. Barr, S.I. "Increased Dairy Product or Calcium Intake: Is Body Weight or Composition Affected in Humans?" in J Nutr, 2003, 133:245S-248S.