GRE argument analysis prompt

"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."

    The conductors of this study came to the conclusion that double doses of vitamin D and calcium will more likely prevent hip fractures.   They conducted a proper experiment with variables and controls, but they did not check for other medical factors that might also result from the extra doses.  Also, does this help octogenarians regain independence or not?
    In the study, nursing-home residents in their eighties took double the normal amount of vitamin D and calcium, and they broke their hips less often than other women who only took normal amounts of vitamins.  Although the paragraph shows no indication that the students tested women who did not take extra supplements, one can assume that they compared the current women subject to extra vitamins to average three-year hip fracture rates.
    There is some concern as to side effects from taking so much of two specific vitamins.  The bone density in these women may be better, but could taking more calcium and vitamin D affect heart rates?  What about blood pressure?  Did anybody monitor the ladies to make sure the vitamins were not causing their bones to overdevelop?  Those conducting this study should take into consideration all aspects of these women's health, not just their bone density.
    The last sentence of the paragraph concludes that the women had less fractures, but readers can still conclude that they still had fractures.  Medical innovations and discoveries can help the older generation live more independently, but other factors need attention.  Women in their eighties are also subject to loss of balance, strokes, blackouts, and dementia that can cause falls and fractures.  While they should get exercise, they should always have a caregiver watching them to make sure they don't get overenthusiastic about their speed or overconfident in their balance.  Although bone density is a major factor in broken hips, there is so much more that this author has not taken into account.
    The scientists conducted a proper experiment with accurate results, but to protect women from falling, fractures, and even death, they need to consider other aspects of their health such as heart problems and cancer that occur in degenerate bodies.  Also, they should never encourage octogenarians to live without some professional caregiver available in case of an emergency.