When the results were tabulated, participants with the highest levels of 25-hydroxyvitamin D had better physical function. And, although physical function declined over the course of the study, it remained significantly higher among those with the highest vitamin D levels at the beginning of the study compared to those with the lowest vitamin D levels. The scientists were not surprised to learn that, in general, vitamin D consumption was very low in this group of otherwise healthy seniors. In fact, more than 90% of them consumed less vitamin D than currently recommended, and many were relying on dietary supplements.

The good news: higher circulating 25-hydroxyvitamin D is related to better physical function in seniors. But it's impossible to tell from this type of research whether increasing vitamin D intake will actually lead to stronger muscles and preserve physical function. This is partly due to the fact that our bodies can make vitamin D if they get enough sunlight. So, it is possible that the participants with better physical function had higher vitamin D status simply because they were able to go outside more often. Indeed, the ominous "chicken-or-the-egg" question can only be answered by carefully controlled clinical intervention trials. Nonetheless, it is possible that getting more vitamin D from foods (like fortified milk and oily fish) or supplements will help maintain youth and vitality as we enjoy longer lifespans. As Houston points out: "Current dietary recommendations are based primarily on vitamin D's effects on bone health. It is possible that higher amounts of vitamin D are needed for the preservation of muscle strength and physical function as well as other health conditions. However, clinical trials are needed to definitively determine whether increasing 25-hydroxyvitamin D concentrations through diet or supplements has an effect on these non-traditional outcomes."

Will vitamin D research lead us to The Fountain of Youth? Probably not. But paying attention to how much vitamin D we get is likely important at every age and will help enhance the "quality" component of life as we enter our senior years.

Source: Federation of American Societies for Experimental Biology