When I moved from LA to Beijing, one of the first things I found myself missing was the SUN. I missed it for the warmth, the beach and the tennis — but I also missed it for the Vitamin D. Many people don’t think about Vitamin D when it comes to supplementation, especially if they spend a great deal of time outside. However, it has been found that 65% of Americans are actually Vitamin D deficient. This is related to sunscreen use, work, societal standards of beauty (light skin — especially here in China), and decreased sunlight in the winter. In addition, it has been found that many people are actually unable to absorb Vitamin D through sun exposure alone. Okay you get tested and, your Vitamin D levels are found to be low — so what?
Vitamin D has been found in the literature to be associated with decreased risk of cancer, diabetes, and heart disease. In fact, a lack of Vitamin D can actually be lethal. In addition to the systemic associations with Vitamin D, it also affects bone health. From a physiologic standpoint, Vitamin D increases calcium absorption, thus increasing bone mineralization. This could affect risk for stress fractures, which are a common injury among athletes that leads to lost training and playing time. If Vitamin D were to be linked to a decreased risk of fractures, supplementation could be a crucial injury prevention piece for those found with deficient levels.
At the end of 2015, the first meta-analysis looking at how Vitamin D affected stress fractures was published. This article looked at 9 studies with military recruits, an active young adult population. Authors Dao et. al. found that Vitamin D levels were significantly lower in the stress fracture groups across the board versus the controls – no matter if the initial measurement was done at the start of basic military training or 4 months in. Although the findings were statistically significant, causality is still missing. But considering the mounting evidence and the benign nature of the supplementation, I believe it can be an effective tool to potentially minimize lost playing time in athletic environments secondary to bone health.
Although my own Vitamin D levels were sufficient in LA, I decided to add a supplement once I moved to Beijing in order to mitigate the secondary effects of winter weather and smog patterns (not to mention the sun culture which I mentioned earlier). Just to share, right now I take Purity Products Advanced D (5,000 IU daily) at the recommendation of Irene Cross, a health counselor through the Integrative Nutrition Program at Columbia University. Given the potentially significant effects of Vitamin D, I believe that it is important for everyone to test for deficiency – especially those in athletic or aging populations.