Vitamin D Deficiency in Athletes

Summer is officially over here in Australia for another year. As the temperatures begin to drop and the daylight hours begin to shorten, being outside gradually becomes just a bit more unpleasant! Over the coming months, we tend to spend a bit less time training and exercising outdoors. But why does this matter?? Quite simply, Vitamin D deficiency.


Vitamin D is an essential micronutrient. Most people will associate Vitamin D with strong bones, as it helps with the absorption of both calcium and phosphorous. However, it has also been shown to play a role in protein synthesis, muscle function, cardiovascular function, inflammatory response, cell growth and musculoskeletal regulation.

Vitamin D is primarily produced through our skin, when we are exposed to UVB light. Approximately 90% of our Vitamin D is produced this way, with the remaining 10% coming from our diet.

Based on the 2011/2012 Australian Health Survey, 23% of adults in had insufficient levels of Vitamin D. This figure was found to be slightly lower in the summer months, but increased over the colder winter months. Yet surprisingly, at the time this survey was taken, only 5% of adults were actually taking Vitamin D supplements! Of course, this survey is now fairly old……so current figures could actually be varied.

Around the world, it is estimated that more than 1 billion adults and children are deficient in Vitamin D.


To put it simply, we aren’t getting enough sunlight. Our busy lifestyles often see us indoors; and when we do go outside, especially for extended periods of time, we rightly protect our skin from sunlight to reduce the risk of developing skin cancer. But this reduced exposure of our skin to UVB radiation means our bodies aren’t producing enough Vitamin D.

As already stated, only about 10% of our Vitamin D is obtained from diet. Some foods, such as fatty fish, eggs and mushrooms, can be comparatively high in Vitamin D. Of course, with reduced exposure to sunlight, increasing these types of foods can help with Vitamin D levels…..but some of us simply don’t eat enough Vitamin D rich foods for this to be beneficial.


Vitamin D is usually associated with bone health, which is of vital importance to athletes. Low levels of Vitamin D can lead to a reduction in bone strength; which, in turn, can lead to an increased risk of stress fractures. Regular physical activity, especially in high impact and contact sports, already carries a risk of bone fractures, so reduced bone strength is obviously not the best scenario for those who exercise.

In terms of muscle strength, some studies show that low levels of Vitamin D can have an impact on muscle strength and performance. Vitamin D has a role in muscle growth, and since muscle growth is vitally important to sports performance and recovery, reduced levels of Vitamin D can have negative effects.

Some new evidence suggests that Vitamin D also plays a role in maintaining healthy lung function. Most sports, especially those with a cardiovascular element, require strong, healthy lungs to supply the body with enough oxygen and get rid of waste. Theoretically, a reduced level of Vitamin D can have an impact of lung function, but more research does need to be done in this area.

Low levels of Vitamin D have also been associated with poor heart health. A poorly functioning heart won’t be able to circulate oxygen and nutrients to working muscles, affecting performance. In addition, high intensity exercise can put additional stress on the heart, which can lead to further problems if the heart muscles are already in poor health.


Well, no.

Low levels of Vitamin D can theoretically have an impact on sports and exercise performance, but that doesn’t mean that you will be getting a performance boost by taking a supplement. Rather, having your Vitamin D levels within the normal range will help your body to function at its optimal levels…..but it won’t give you that extra kick we all secretly hope for!


While low levels of Vitamin D aren’t good for a healthy body, high levels can also cause a few problems. Vitamin D helps with the absorption of calcium into the body…….as a result, higher levels of Vitamin D can lead to increased levels of calcium, known a hypercalcemia.

Hypercalcemia has many effects on the body, including:

  • digestive distress, such as vomiting, nausea, constipation, and stomach pain
  • fatigue, dizziness, hallucinations, and confusion
  • loss of appetite
  • excessive urination
  • kidney stones, kidney injury, and even kidney failure
  • high blood pressure and heart abnormalities
  • dehydration

Obviously, none of these things are ideal, especially for athletes who are trying to perform at their peak.


While low levels of Vitamin D can have a negative effect on sports performance, it doesn’t automatically mean you should rush out and grab a supplement. With a balanced diet, in addition to adequate sun exposure, your body’s Vitamin D levels should be well within a healthy range, allowing your body to perform at it’s best.

If you supplement your body with more Vitamin D than you need, it won’t give you a performance boost…..instead, it could possibly be doing you harm!

The best thing you can do is head to your doctor and ask for a blood test….this will determine what your Vitamin D levels are. If you need to take a supplement due to low levels, talk to your friendly pharmacist about a suitable product!

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s