Vitamin D has been getting a lot of attention in the sports nutrition community in recent years for it’s potential benefits in performance and recovery. Since the days are getting shorter and sunlight is at an all time low, what better time than now to discuss Vitamin D!
Vitamin D is a fat-soluble vitamin that promotes calcium absorption in the gut and regulates calcium and phosphorous in the blood stream, which helps maintain bone health. Vitamin D is often in the spotlight for being essential for bone health, which is true, but I think this nutrient deserves more credit than it’s given. In fact, it has a host of metabolic uses. Vitamin D regulates over 900 gene variants and can affect many processes such as exercise-induced inflammation, glucose metabolism, and skeletal muscle performance to name a few. If you’re an athlete, getting adequate amounts of Vitamin D is important to reduce your risk for things like stress fractures, muscle weakness, and cognitive functioning. Due to the chemical nature of exercising, athletes may be susceptible, if not more than the general population of becoming Vitamin D deficient. Evidence suggests that 56% of athletes are deficient in this nutrient (Farrokhyar et al., 2014). This could be a huge hindrance to your performance.
What’s makes Vitamin D such a popular topic in the athletic community is the discovery of Vitamin D cell receptors in skeletal muscle tissue. It hasn’t been until recently that research has looked at Vitamin D supplementation and its effect on muscle strength, power and endurance.
A recent study examined 14 elite rowers over an 8 week time period to examine the effects of Vitamin D supplementation on V02 max (the ability to transport and utilize oxygen in the blood to various tissues). One group of athletes were supplemented with 6000 IU of Vitamin D daily while the placebo group was not given any supplementation. V02 max was significantly higher in the test group compared with the placebo (Jastrzebski, 2014). This is important for endurance athletes because V02 max increases aerobic capacity. Another recent study investigated high dose Vitamin D supplementation in male soccer players. The test group showed significant improvement in their force and power production (Close et al., 2013).
But where can I get Vitamin D?
Vitamin D is available from both diet and sunlight. There are two forms of dietary Vitamin D; one from plant sources and the other from animals. Plant-based Vitamin D is not as well absorbed, however. Below are examples of foods that are rich in Vitamin D:
Cod Liver Oil
5 ml (1 tsp)
Salmon, sockeye/red, canned, cooked or raw
75 g (2 ½ oz)
75 g (2 ½ oz)
75 g (2 ½ oz)
250 ml 91 cup)
Egg yolks, cooked
Unfortunately, sun exposure in Canada for the next few months is minimal and dietary sources of Vitamin D are quite limited. Even if you were to intake the foods listed above on a daily basis, the amount of Vitamin D is inadequate to meet needs for most individuals. The most effective way to get Vitamin D during the winter months is through supplementation. Choose Vitamin D3 tablets, otherwise known as Cholecalciferol. Health Canada recommends men and women between 19 and 70 aim for 600 IU and not to exceed 4000 IU per day. The Canadian Cancer society recommends 1000 IU per day during the fall and winter for all Canadians, and 1000 IU yearlong for those at higher risk of Vitamin D deficiency category (dark skin tones, little sun exposure year long, older adults).
It is important to note that sample sizes in research studying athletes are often quite small. When you want to study an elite bunch of human beings that excel in one area, your sample pool is already quite limited. This makes it difficult for researchers to have statistically significant outcomes when studying elite athletes. Many studies that look into Vitamin D supplementation and athletics are not statistically significant because of this. But that does not mean that their outcomes aren’t important. Vitamin D is essential, and supplementation this time of year is highly encouraged by many Sports Dietitians. Do your bones, mind, and performance a favour and get some of that Vitamin D in you!
Emilie Trottier, Registered Dietitian, Sports Dietitian
Farrokhyar F, Tabasinejad R, Dao D, Peterson D, Ayeni O, Hadioonzadeh R, et al. Prevalence of vitamin D inadequacy in athletes: A systematic-review and meta-analysis. Sport Med. 2014;5:365–78.
Jastrzębski Z. Effect of vitamin D supplementation on the level of physical fitness and blood parameters of rowers during the 8-week high intensity training. Facicula Educ Fiz şi Sport. 2014; 2:57-67.
Close GL, Russell J, Cobley JN, Owens DJ, Wilson G, Fraser WD, et al. Assessment of vitamin D concentration in non-supplemented professional athletes and healthy adults during the winter months in the UK: implications for skeletal muscle function. J Sports Sci. 2013;31:344–53.
Food Sources of Vitamin D. Dietitians of Canada. http://www.dietitians.ca/Your-Health/Nutrition-A-Z/Vitamins/Food-Sources-of-Vitamin-D.aspx