Most people realize that vitamin D assists the body in absorbing calcium. This assisting role helps the body have strong bones. What most people don’t realize is that this role only represents 15% of what vitamin D does. There are over 200 genes in our body that have vitamin D receptors. This means that having adequate vitamin D levels allows our body to function correctly at the genetic level, enhancing many things from immune function to muscle strength.
A new study published in the Journal of Clinical Endocrinology and Metabolism looked at the relationship between vitamin D status and fat content of muscles. Our muscles naturally store fat as an energy source. But a higher muscle fat content is associated with lower levels of strength and performance.
This current study measured blood levels of vitamin D and, using a CT scan, measured the amount of fat in muscles. What the researchers found was an inverse relationship between the two measurements. The lowest vitamin D levels were associated with the highest amount of fat in the muscles. A reasonable assumption is that vitamin D insufficiency is associated with a decrease in muscle strength.
I always encourage people to get their serum Vitamin D levels checked. Once you know that number, you will know how much vitamin D is best for you to take. I generally recommend between 1500 and 2000 IU per day. It is very difficult to get this amount from food. And although it is possible to get such a level from sun exposure, I don’t recommend forgoing sunscreen. So personally, I take 2000 IU per day combined between my multivitamin and a vitamin D supplement. I typically recommend the Nature Made brand to clients because they submit to strict quality testing by the United States Pharmacopeial; this way you know you are getting exactly what is on the label.
© Randy Bird, MS, RD, CSSD, CSCS and Randy Bird Sports Nutrition, 2010.
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