What’s the one nutrient that many athletes seem to be lacking?
It’s vitamin D!
Why?
Well I’ll tell you.
You see, vitamin D is called the sunshine vitamin meaning it gets its “power” through sun exposure.
But if the sun is abundant everywhere, wouldn’t it make sense for everyone to be abundant in Vitamin D?
Well that’s just not the case, because today so many people are vitamin D deficient.
And it affects athletes the worst!
Vitamin D is a fat-soluble vitamin that plays a humongous role in bone health, muscle function, adaptive immunity, and many human diseases like cancer, diabetes, and musculoskeletal health.2
Vitamin D Deficiency
In fact, vitamin D deficiency is a global public health issue.
Did you know that over 1 billion people on the planet have vitamin D deficiency?
It is a serious issue that needs serious attention.
But if you’re an athlete who so happens to live in the northernmost regions of the globe.
Especially one that plays an indoor sport, trains indoors year-round & rarely gets outside during the day.
You’re probably less likely to get adequate amounts of that elusive vitamin D.
Meaning you’ll probably face an uphill battle against muscle weakness, pain & rapid decrease in mood levels
Here’s what else Vitamin D is responsible for:1
Bone and teeth health
Healthy Weight management
Muscle strength, fiber size, and type
Vitamin D deficiency occurs as blood levels drop to less than 20 ng/mL (< nmol/L), while vitamin D insufficiency for athletes is defined as blood levels reaching between 20-32 ng/mL (50-80 nmol/L).
Research has indicated that 40-50 ng/mL (100-125 nmol/L) seems ideal for optimizing athletic performance.1
Who's at High Risk?
Those with a decreased dietary intake:Like celiac disease, short bowel syndrome, gastric bypass, inflammatory bowel diseases
Those with a decreased sun exposure. Roughly 50% to 90% of vitamin D is absorbed through the skin. Twenty minutes of sunshine daily, with 40% of skin exposed, is required to prevent deficiency.
Aging adults: The ability to effectively use vitamin D decreases by as much as 75% as we age.
Overweight and obese individuals: Those who carry excess body fat can increase their risk of up to 55% due to vitamin D being trapped in adipose tissue and being unavailable in the bloodstream.
The Indoor Athlete
Athletes like hockey players specifically spend a great deal of their time training, conditioning, and competing indoors, making it difficult to attain vitamin D through sun exposure.
To add to the statistics, another study found that as much as 88% of the population receives less than the optimal amount of vitamin D.3
Several studies link vitamin D status to bone health and the overall prevention of bone injuries in the athletic population.
Research and Vitamin D Deficiency
Studies have illustrated that not enough vitamin D levels are linked to a greater risk of stress fractures in young men and women, which was published in the Journal of Foot & Ankle Surgery.4
A study published in the journal, Nutrients assessed vitamin D status among college men and women basketball players in the season. The players were either allocated a high-dose, low dose, or no vitamin D depending on their circulation 25-hydroxyvitamin D levels at the beginning of the study to identify the optimal dosage of vitamin D3 supplementation optimal status.
The findings demonstrated that 13 of the 20 participants were vitamin D insufficient at baseline. Another finding was that of the athletes sampled, and the darker skin pigmentation increased the risk of vitamin D insufficiency at baseline.
Researchers found that most athletes who were vitamin D insufficient benefited from supplementation of 10,000 IU to improve their status.5
The study also suggests that professional football players deficient in vitamin D may also have a greater risk of bone fractures.7
Increasing endurance & "firepower" is every athlete’s desire as it can translate into improved performance on the field. Your muscle tissues have several key receptor sites for vitamin D, and they will help support power production.1
A study in soccer players found that increasing baseline vitamin D status over an 8-week period leads to increased vertical jump and 10-meter sprint times.9
Of course, we need further research in this area to identify the relationship between vitamin D levels and power output.
Still, the current literature is promising and that, at minimum, baseline vitamin D levels should be desired.
Sources of Vitamin D
The best vitamin D sources include egg yolks, mushrooms, fortified milk, yogurt, cheese, salmon, mackerel.8
Vitamin D rich food sources:
6 oz. fortified yogurt = 80 IU
3 oz. of salmon = 794 IU
1 cup of fortified cereal = 40 IU
1 cup of fortified milk = 120 IU
1 egg yolk = 41 IU
1 cup of fortified orange juice = 137 IU
Real-World applications
Athletes who train indoors, consume little vitamin D rich sources and live > 35 degrees north or south may benefit from a vitamin supplement of 1,500 - 2,000 IU per day to keep vitamin D concentrations within a sufficient range.
Athletes who may have a history of stress fractures, frequent illness, pain or weakness, or overtraining signs should have their vitamin D status evaluated.
Vitamin D is best absorbed when taken with a meal that contains fat.
It is important to follow up with a physician to assess vitamin D levels further and meet with a registered dietitian to discuss nutrition intervention further.
References
1. Ogan, D., & Pritchett, K. "Vitamin D and the athlete: risks, recommendations, and benefits." Nutrients, 5(6), 1856–1868. 2013.
2. Umar, M., Sastry, K. S., & Chouchane, A. I., "Role of Vitamin D Beyond the Skeletal Function: A Review of the Molecular and Clinical Studies." International Journal of Molecular Sciences, 2018,19(6),1618.
3. Bendik, I., Friedel, A., Roos, F. F., Weber, P., & Eggersdorfer, M. "Vitamin D: a critical and essential micronutrient for human health." Frontiers in Physiology, 5, 248, 2014.
4. Elsevier Health Sciences. (2015, December 14). "Low levels of vitamin D may increase risk of stress fractures in active individuals: Experts recommend active individuals who participate in higher impact activities may need to maintain higher vitamin D levels." ScienceDaily. Retrieved October 19, 2020.
5. Sizar O, Khare S, Goyal A, et al. "Vitamin D Deficiency." [Updated 2020 Jul 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-.
6. Sekel, N.M.; Gallo, S.; Fields, J.; Jagim, A.R.; Wagner, T.; Jones, M.T. "The Effects of Cholecalciferol Supplementation on Vitamin D Status Among a Diverse Population of Collegiate Basketball Athletes: A Quasi-Experimental Trial." Nutrients, 2020, 12, 370.
7. National Institutes of Health – Office of Dietary Supplements – "Vitamin D – Fact Sheet for Health Professionals." [accessed October 19, 2020].
8. Maroon JC, Mathyssek CM, Bost JW, Amos A, Winkelman R, Yates AP, Duca MA, Norwig JA. "Vitamin D profile in National Football League players." Am J Sports Med. 2015 May;43(5):1241-5. Epub 2015 Feb 3. PMID: 25649084.
9. Close, G. L., Russell, J., Cobley, J. N., Owens, D. J., Wilson, G., Gregson, W., Fraser, W. D., & Morton, J. P., "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." Journal of Sports Sciences, 31(4), 344–353. 2013.