Vitamin D and Your Full Potential

Just in time for winter. Throughout December we highlighted the role Vitamin D plays in your performance. Vitamin D is not really a vitamin; it acts more like a hormone with effects on over 900 physiologic processes in our bodies. We have Vitamin D receptors in our intestines, lungs, breast, and bone making it one of the most important vitamins. Research is defining it's role in various diseases but how is it effecting your performance?

Week 1: Vitamin D Deficiency and the Athlete

Of Canadian adults, 32% are considered to be deficient in Vitamin D. That is almost 1/3 of Canadians who do not have Vitamin D levels sufficient to maintain bone mass. To provide some context: blood levels less than 50nmol/L is considered deficient, a level from 50-80nmol/L is considered insufficient, and a level greater than 100nmol/L is considered optimal. 

How does this compare to athletes?

Athletes have consistently shown to have insufficient Vitamin D levels as well, despite outdoor training. From soccer players (1), basketball players (2), gymnasts (3), football players (4), and runners (5) a large proportion have insufficient levels. It doesn't seem to matter if your sport is primarily outdoors or indoors, athletes tend to be low in vitamin D. 

Various reasons have been proposed for this insufficient level in outdoor athletes, including; over use of sunscreen, low dietary intake, and physical stress from training leading to more bone turnover and a greater demand of Vitamin D. It is most likely a combination of these factors that lead to an athletes insufficient levels. 

What this means for you? 

Getting your vitamin D levels tested is the first step in optimizing your levels and one notch closer to reaching your full potential. 

Week 2: Vitamin D and Performance Enhancement

Last week we highlighted how prevalent Vitamin D deficiency is in the general population and in athletes. This week, we'll discuss some of the ways optimal Vitamin D improves your performance and how insufficient levels may be harming it. 

We know that there are Vitamin D receptors on muscle tissue, which means there is a direct effect of Vitamin D on this tissue. This is clearly important when it comes to athletes. What does the evidence say?

1. In a non-athlete population the highest blood levels of Vitamin D was associated with increased upper and lower body strength (1).
2. There is some information to point to an increased VO2max (ability to use oxygen) with greater Vitamin D levels (2, 3, 4, 5).
3. An animal model shows that high doses of Vitamin D decreases muscle recovery time from injury (6).
4. A human study showed supplementing with Vitamin D at moderate doses helped participants maintain muscle power after muscle damaging exercise (7).
5. Finally, and most importantly, Vitamin D status and supplementation has been shown to increase 10m sprint times and vertical jump in an athlete population (8).

Additionally, the effect on bone health is well understood and proper Vitamin D levels may prevent overuse stress fractures (9).

What does this mean for you?

Getting your levels tested and implementing a proper Vitamin D replacement strategy is important to optimize your performance, improve recovery time, and get another check-box on the way to your full potential. 

Week 3: Vitamin D's Hormonal Effects

Like I mentioned above, Vitamin D acts like a hormone, but it also effects other hormones. Certain ones are of interest to athletes since they can promote muscle building and bone strength, among other benefits. 

Testosterone
The male androgenic hormone testosterone is always a popular topic in sports and performance and for good reasons. Testosterone is associated with increased muscle growth, strength and power in both sexes (1). Vitamin D status and testosterone levels are related; men with sufficient levels of Vitamin D had higher levels of testosterone (2). Furthermore, supplementing with Vitamin D was associated with an increase in testosterone (3). 

Estrogen
The female hormone is also a popular topic not only in sports, but also in female and male health in general. Too much estrogen in females can cause uncomfortable menstrual cycles, weight gain, bloating, along with many other issues. Too much estrogen in males can lead to lowered sex drive, loss of muscle mass and weight gain. Vitamin D has been shown to lower estrogen in a female population (4). The reason for this is unclear, but could be related to a decreased aromatase expression (the enzyme responsible for conversion of testosterone to estrogen) (5). 

Sex Hormone Binding Globulin (SHBG)
SHBG is a protein in the blood responsible for binding testosterone and estrogen (with a greater affinity to testosterone) to decrease circulating levels. The more you have, the less free testosterone available for physiologic processes. Vitamin D is associated with a decrease in SHBG, making more testosterone available (6).

Remember, while these studies show an increase or decrease in a hormone, it is helpful to think that Vitamin D (or other natural options) have a modulating role; increasing levels if they are low, and decreasing levels when they are too high. It is also important to question whether or not the increase or decrease in hormones would be relevant to you. 

What does this mean for you?

Getting your levels tested and implementing a proper Vitamin D replacement strategy is important to optimize your performance, improve recovery time, and can help reach your full potential. 

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