An essay on "vitamin D and calcium against fractures"

Hello,

Could you please take a look at any part of the following essay

and point out any errors or places that had better be amended?
Thanks in advance.

Argument (not to be checked):

"Typically, as people age, their bone mass decreases, making them more vulnerable to bone fractures. A recent study concludes that the most effective way to reduce the risk of fractures in later life is to take twice the recommended dose of vitamin D and calcium daily. The three-year study followed a group of French women in their eighties who were nursing-home residents. The women were given daily supplements of twice the recommended dose of vitamin D and calcium. In addition, the women participated in a light weightlifting program. After three years, these women showed a much lower rate of hip fractures than is average for their age."

Analysis:

The main claim of the argument is that taking daily a double norm of vitamin D and calcium is the most effective way to reduce the risk of any fracture in later life. At first glance, it seems sensible, but after a closer look the evidence supporting the central claim appears to be not strong enough.

First, the conclusion of positive influence of vitamin D and calcium was made for people of all ages, countries of origins, and genders while having been tested only on elder French women. Also, there were not a word of the number and health peculiarities of people on whom the measurements were performed. Thus, the sample of people having been tested is not representative, that is the characteristics of this group of people not necessarily reflect those of the larger group of people about whom the final conclusion is made.

Second, the positive results got after three years of testing might be caused by the weightlifting program and have nothing to do with the increase in reception of vitamins and minerals. It would be reasonable to perform all measurements on two similar groups of people, the first of which would not participate in the weightlifting program, while the second of which would. That would help separate the effect vitamins and minerals cause from the summary effect of those and weightlifting.

Third factor not taken into account is whether these people were getting other medicals during the test period. It is highly probable that they were, since elder people in most cases should regularly take some medicine. Some of those do not take the medicine ignoring the prescription, but elder people living at a nursing-home are usually forced to take it. And these off-site medicine might somehow strengthen bones and narrow down the role of vitamins and minerals.

Another general conclusion made is that the reception of additional vitamins and minerals helps prevent all kinds of fractures, while the mentioned statistics indicates the decrease only in the number of hip fractures. It is a possibility that there were some other conditions that helped reduce the rate of hip fractures. For instance, for some people wheelchairs might had been provided, so that they were not at risk of such fractures any longer.

Finally, it was not stated why the increase in vitamins and minerals reception should be exactly twofold. And it was not anyhow warranted why this bone hardening method is, if at all effective, the most effective. Neither any other methods nor comparison of their efficacy were provided.

As a conclusion, it appears that the author's "universal" proposition of an increase of reception of vitamin D and calcium as the best method of reducing the risk of any fractures does not have much base and should be considered as premature. In general, an idea of increase in reception of vitamins and minerals seems to be a good, but more clear research should be performed so that to begin realization of this solution into practice.

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Victor