In between my vaguely successful attempts at genotyping mice (I'm currently working in the nutrition lab in the School of Molecular Bioscience, Sydney Uni), I have been reading the new USDA Dietary Guidelines. Take a look at the stats on diet related diseases in the US, really scary stuff!
Note the figures for osteoporosis - this can be reduced if people eat more calcium containing foods and undertake weight bearing exercise. Australian women fall short of eating the recommended daily intake (RDI) of calcium which ranges from 1000 mg a day to 1300 mg a day pre and post menopause respectively. Making matters worse, only 30 - 40% of calcium is absorbed from food whilst sodium, a high protein diet, caffeine and ageing increase its excretion (a whopping 150 mg of calcium is excreted with every 50g of protein ingested).
The best bioavailable source of calcium is found in dairy foods (milk, cheese, yoghurt). Milk provides approx. 230 mg of calcium per 200 ml regardless of its fat content. The same amount of calcium can be ingested in 120 g of plain yoghurt and 30 g cheese. Other good sources include nuts and seeds, tinned fish with bones, spinach and legumes. Vitamin D helps the absorption of calcium and it is recommended you spend a few minutes in the sun every day without sun screen. Osteoporotic fractures can lead to long term pain and disability, loss of independence and premature death. Simply put, you can reduce the likelihood of having an osteoporosis related fracture by eating the right amount of calcium, doing weight bearing exercise and getting a little sun!
USDA Dietary Guidelines for Americans 2010
FSANZ Australian Food Composition Tables 2006
Samman, S. Calcium. School of Molecular Biosciences, University of Sydney