In the new study, published in the Journal of Clinical Endocrinology and Metabolism, Robin M. Daly from the University of Melbourne and colleagues randomly assigned men aged 59 to 70 to an exercise program, drinking milk fortified with calcium and vitamin D, doing both, or doing nothing.
They measured the men's bone density before and after the study, which took place over 18 months, but they didn't look at fractures.
At the end of the study, men who exercised had higher bone density than those who had supplemented their diet with 1000 mg calcium and 800 IU vitamin D per day.
Adding the supplements to the exercise program provided no extra benefit, hinting that the men already had enough vitamin D and calcium in their diets to be able to boost their bone strength through exercise alone.
The recommended daily intake of vitamin D is 600 IU in adults up to age 70, and 800 IU for older people, according to the National Institutes of Health (NIH). A 6-month supply of vitamin D supplements can be bought for less than $10, and many multivitamins contain the recommended daily dose of vitamin D.
As for calcium, the NIH advises 1,000 mg per day for men ages19-70, and then 1,200 mg per day for men older than 70.
To reduce the risk of bone weakening, the NIH recommends not smoking, drinking less alcohol and exercising more. (Reuters Health/ January 2011)