“When we repeatedly see bones fracturing and muscles being injured again and again, we begin to ask ‘Why aren’t they healing?’ And one thing we’ve found is that it could be related to vitamin D levels,” Yagnik says.
He recalls a study in which over half of the 89 NFL players who had their blood levels measured had insufficient or deficient amounts of vitamin D. On further study, the researchers found that these players also suffered more muscle injuries than their teammates who tested normal for the vitamin.
The connection between vitamin D and muscle and bone health is a work in progress.
“We can see that there’s a relationship but we aren’t really sure why these things happen,” says Westerdahl, noting that will take more research.
Kiebzak did a study with elderly patients in a rehabilitation unit at St. Luke’s Hospital in Houston. He found that those patients with lower vitamin D levels had to stay in the hospital longer, were less able to get up and around and had less muscle strength than those with normal vitamin D levels.
And according to Westerdahl, other studies have shown that adults with healthy amounts of vitamin D have improved strength in fast twitch muscle fibers in their arms and legs. These are the muscles that golfers, tennis players and weight lifters use for high force but low endurance.
For those with a vitamin D deficiency, it’s relatively easy and inexpensive to correct. Doctors often recommend oral mega-doses of the vitamin taken once a week for eight weeks. “After that, a multivitamin should keep it in line,” Kiebzak says.
The FIU football player with the fractured foot was prescribed 50,000 IU of vitamin D taken orally for eight weeks. That caused his serum levels of vitamin D to improve. Daily supplementation of 2000 IU of vitamin D was continued after that.
The Institute of Medicine recommends that healthy adults, ages 14 to 70, get 600 IU of this vitamin daily; adults over 70 require 800 IU.
Vitamin D is found naturally in only a few foods including fatty fish such as salmon, tuna and mackerel; cheese and egg yolks. And it is sometimes used to fortify such things as milk, cereals, yogurt and orange juice.
Because it’s not widespread in our food supply, it’s difficult to eat enough.
But man was not created to get vitamin D from food alone, says Westerdahl.
There’s a precursor of vitamin D in your skin that is converted to the active form of the vitamin by the ultraviolet light from the sun. So if you don’t get enough sun exposure, if you have dark pigmented skin containing melanin that can interfere with the process or if you wear sunscreen, your body won’t be able to make the vitamin D it needs.
And that’s when you are most likely to become deficient.
Of course in South Florida, there are concerns that too much sun exposure can cause skin cancers. So don’t overdo it. But in general, some doctors recommend you spend from five to 30 minutes in the sun two times a week at the middle of the day.
“It’s a pretty vague recommendation,” Yagnik says.
Although the doctors can see the benefits of vitamin D in their patients, what’s needed to understand the issues and to come up with more specific recommendations are randomized studies of people with various health issues who have low vitamin D levels in their blood. Each study would compare the outcomes of one group that is given vitamin D supplements with another that is not.
“But let’s face it, there are ethical issues with doing those kinds of studies,” Kiebzak says.
So the answers about vitamin D may never be clear cut. But the questions will continue to be asked.
In fact, you can bet there are many athletes wondering if taking more vitamin D can actually enhance their athletic performances and prevent injuries.
Once again, the doctors don’t really know.
“That’s just one of the things we are looking at now,” Yagnik says.