During childhood and adolescence our bones increase in size and mass. During our early twenties, our skeletons reach maturity and we achieve our peak bone mass, which is the maximum amount of bone that we will have in our life. By maximising our bone density and achieving our genetic potential when we’re young, we can reduce our risk of osteoporosis in later life. Osteoporosis is a condition affecting over one million Australians in which the bones become porous and brittle and are more likely to fracture if we have a fall. This may not seem like a big deal to a teenager, but for an older person it can mean pain, disability, moving into a nursing home and a higher risk of mortality.
Low calcium intake is a risk factor for osteoporosis, which makes the latest Australian Health Survey results rather concerning. The survey results show that boys aged 14–18 have a mean calcium intake that is 12% below the estimated average requirement, and that 14–18-year-old girls are a whopping 30% below. That’s almost one in three teenage girls at risk of calcium deficiency. And as women are at greater risk of developing osteoporosis due to the drop in oestrogen levels during menopause, this is an alarming statistic.
So how do we ensure young people get enough calcium?
The Australian Dietary Guidelines recommend that adolescents eat three-and-a-half serves of dairy foods a day to meet their 1300mg recommended daily intake (RDI) of calcium. This might look like:
– 30g high-fibre breakfast cereal with half a cup reduced-fat milk, topped with fruit and 100g reduced-fat natural yoghurt (half a cup of milk is half a serve of dairy and 100g yoghurt is another half serve)
– salad and cheese sandwich for lunch (1 slice of cheese is half a serve of dairy)
– blueberry and banana after-school smoothie (1 cup milk is one serve of dairy)
– 200g reduced-fat natural yoghurt topped with nuts for dessert (one serve of dairy)
If your teenager doesn’t enjoy dairy or has an allergy or intolerance you’ll need to make sure they’re getting enough from other sources. This means a varied, healthy diet that includes seafood, green vegetables, nuts and seeds and soy products like tofu plus a variety of calcium-fortified products such as soy or rice milk, bread, cereals and juice.
Use the list below to estimate your teenager’s calcium intake. If you don’t think their achieving 1300mg per day, stock up on a range of calcium-enriched products next time you’re at the supermarket.
|Food||Serving size||Amount of calcium (mg)|
|Tofu (firm, set in calcium sulphate)||170g||544|
|Calcium-fortified milk such as Anlene or Pura Boost||1 cup/250ml||520|
|Calcium-fortified soymilk||1 cup/250ml||300–400|
|Calcium-enriched rice milk||1 cup/250ml||317|
|Hard cheese||2 slices/40g||300|
|Low-fat cow’s milk||1 cup/250ml||273|
|Sardines with bones in springwater||84g (drained weight)||254|
|Full-cream cow’s milk||1 cup/250ml||252|
|Seafood (prawns, mussels, snapper, oysters)||100g||126–173|
|Salmon with bones||Small can, drained||170|
|Calcium-fortified cereal such as Weet-Bix Kids||30g||120|
|Calcium-fortified bread such as Burgen Soy and Linseed||1 slice||120|
|Calcium-fortified orange juice with no added sugar||½ cup/125ml||100|
|Green vegetables (kale, bok choy, broccoli, watercress, celery)||1 cup, chopped||40–100|
|Chickpeas, cannellini beans, edamame||1 cup||77–98|
|Almonds with skin||30g||75|
What else can we do to promote strong bones?
The body needs vitamin D to absorb calcium. While foods such as oily fish and eggs contain vitamin D, we produce most of our vitamin D in our skin when it is exposed to ultraviolet radiation (UV). This is easy to achieve in summer, but in winter we need to spend two to three hours outdoors every week, exposing as much skin as tolerable.
Weight-bearing physical activity is also important for strong bones. Australia’s Physical Activity and Sedentary Behaviours Guidelines recommend that adolescents accumulate at least 60 minutes of moderate to vigorous physical activity a day. If your teenager is being active outdoors everyday you can be confident that their growing muscles and bones are benefitting from the exercise as well as the vitamin D.
 Cauley JA, Thompson DE, Ensrud KC, Scott JC, Black D. Risk of mortality followingclinical fractures, Osteoporosis International 2000;11:556–561.