It's that time of year again when it's cold and gray outside. Our daylight hours are limited and the excitement of the holidays has worn off. Everyday reality is setting in and maybe the winter blues are too. It may already be difficult for you to stick to that new year's resolution…if you’re struggling to stay positive and motivated you may want to check your vitamin D levels. In addition to a lack of sunlight, vitamin D deficiency has been linked to Seasonal Affective Disorder (SAD).
Vitamin D plays a major role in disease prevention and maintaining optimal health. It has long been known to be important for bone health, but it serves many other functions. Vitamin D has been linked to the prevention of cancer, immunity to the cold, and the reduction of depression. It supports cardiovascular health and proper immune function, making you much less likely to get the flu when you have optimal levels!
Your body can make its own vitamin D when you expose your skin to sunlight. The UVB rays react with your skin and produce vitamin D3, which is sent to your liver and converted to calcidiol, also known as 25(OH)D. Generally, 20-30 minutes of mid day sun exposure is sufficient for light skinned people, if you have darker skin you may need to double the time. Interestingly, once your body has produced enough vitamin D through sun exposure, those same UVB rays will begin to prevent excess vitamin D production. This means there’s no need to worry about getting too much vitamin D from sunlight.
This is a great natural system, however, if you live the US (or other northern latitudes) it’s very difficult and likely impossible to meet your Vitamin D needs from sunlight during the winter months.
Below is a map of the US for the month of January showing the potential for Vitamin D Synthesis ***
During this time just about everyone in the US is in need of vitamin D supplementation. One caveat with taking vitamin D orally is that it is possible to take too much. However, this is unlikely as you would have to take large amounts very frequently. As an oral supplement vitamin D3 is preferred over D2 as researchers have found that vitamin D3 is twice as effective as vitamin D2 in raising levels in the body. Recent research indicates that taking 4000 IU - 8000 IU per day will put you at an optimal level. When you take vitamin D orally it is sent to your liver where it is converted to calcidiol, or 25(OH)D, the same as when your body creates it from sunlight. Since vitamin D is fat soluble it’s beneficial to take your vitamin D supplement with a healthy fat for better absorption. The only way to know for sure the proper supplementation amount for you is to get a blood test for 25(OH)D before you begin supplementing and check it after 6-8 weeks. An optimal level for 25(OH)D is 50-60 ng/mL.
In addition to playing a part in your emotional health maintaining optimal Vitamin D levels will support and enhance your athletic performance. Studies have shown that athletes with optimal serum vitamin D concentrations bounced back better after intense exercise. I have been keeping track of my vitamin D levels since 2012. As athletes, we know that being able to get out there and feel good in our training also plays a part in our sense of well being!
***Taken from Dr. Joseph Mercola's Vitamin D Resource Page http://www.mercola.com/article/vitamin-d-resources.htm