Is Vitamin D Deficiency a Performance Blocker?

As awareness of our bodies grows, taking things like vitamin D levels into account is becoming increasingly important.

The strongest man in the fictional universe, Superman, derives his power from the sun. Chances are you’re not a superhero, but this phenomenon isn’t purely science fiction. In fact, it imitates your own athletic power.

The sun, particularly the vitamin D it provides, is essential to your strength, endurance, resilience, athletic performance, and longevity. But athletes and coaches already know this. That’s why more sports teams are beginning to focus on the value of vitamin D to help players boost performance and avoid injuries.

Since the early 20th century, athletes and coaches have suspected that ultraviolet rays from the sun have a positive impact on the performance of players on the field. Now, we know that those benefits are tangible and come mainly in the form of essential vitamin D.

But because we absorb most of our vitamin D from sunlight, people in northern climates who have limited sun exposure often have insufficient or deficient levels. Therefore, athletes across regions need to pay special attention to the vitamin D in their meals and, if necessary, take supplements to ensure healthy levels.

For most athletes who need to boost their athletic prowess, more vitamin D can improve strength, speed, endurance, and lower the risks of serious injuries. It can also lead to faster fat loss and improved immune function—two results that every athlete can appreciate.

Vitamin D in the World of Sports

The studies that have highlighted vitamin D’s benefits and the dangers of deficiency are relatively new. But athletes and those working with them have suspected the importance of vitamin D for decades. In the 1950s, for instance, Eastern bloc countries put their athletes in front of sunlamps because they were convinced of a connection between vitamin D and athletic performance.6 They were right. As a result, the runners boasted a 7.4 percent improvement in their 100 meter times.

Why did it work? Because vitamin D is a hormone that contributes to optimal skeletal and muscle function. Without enough of it, the body won’t function as well as it’s designed to, and athletes can’t perform as efficiently as they’ve trained to. Deprived of ample sunlight in their environment, the Eastern bloc athletes were able to boost their vitamin D levels with the sunlamps and show a clear improvement in their performance, recovery, and longevity.

On the opposite side of the coin, in 2010, the Chicago Blackhawks NHL team announced that its physicians had begun diagnosing and treating vitamin D deficiency8 in all of its players. Additionally, a study of the New York Giants was presented at a 2011 meeting of the American Orthopaedic Society for Sports Medicine. The study showed definite correlations between low vitamin D levels,2 increased injuries, and poor performance.

And in 2015, the Pittsburgh Steelers published a study in the American Journal of Sports Medicine that discovered the same association among injured and poorly performing players.

Coaches, trainers, and teams are becoming more interested than ever in testing players for vitamin and mineral status. Vitamin D plays an important role in hundreds of biological processes, including calcium absorption for stronger bones and a stronger immune system. In other words, adequate vitamin D intake helps athletes stay strong and healthy enough to keep playing the sports they love.

In addition to helping maintain body composition, vitamin D is known for increasing an athlete’s strength and power.

The Benefits of Getting Enough Vitamin D

It takes more than just training to sculpt an athlete’s physique into an optimal, high-performing machine. It also takes a body that can handle the training and that can operate at maximum efficiency. To achieve that efficiency, vitamin D is essential on many levels, from optimizing body composition to increasing strength, power, and resilience.

One of vitamin D’s most notable benefits is its ability to improve insulin sensitivity,1 which has been shown to help prevent and manage both types of diabetes and balance out hormones. Hormone regulation helps with fat loss and muscular hypertrophy and boosts your immune system’s ability to regulate inflammation. Inflammation regulation is known to aid in recovery and help prevent autoimmune diseases from developing.

In addition to helping maintain body composition, vitamin D is known for increasing an athlete’s strength and power. It reduces protein loss within muscles and increases the size and strength of fast twitch muscle fiber. By improving protein synthesis,9 the vitamin decreases the amount of fat infiltration in the muscles. Referred to as fatty muscle, this infiltration could impair the strength and efficiency of muscle functioning.

Proper intake of vitamin D can also decrease soft tissue injuries. A chronic lack of this hormone causes abnormalities in muscular contraction and relaxation,4 which is important to note because many injuries are caused by a lack of force absorption. To properly absorb force on the playing field, certain muscles need to contract while their antagonist muscles relax. By improving the strength, speed, and responsiveness of your muscles, vitamin D makes soft tissue injuries less likely.

Vitamin D: The Ingredient for Success

Because everyone’s body is different, there’s still uncertainty about what exactly constitutes a normal range of vitamin D levels.5 The 25-hydroxyvitamin D reference ranges from 30ng/ml to 100ng/ml, though many experts express that 50ng/ml should be considered the low end of normal.

Regardless, some athletes have levels that are too low by any standard and may not even realize how much it’s affecting them. One athlete I worked with was diagnosed with Crohn’s disease while in college and suffered from inflammatory side effects for years without finding relief. We started by having her blood work done, and the results revealed an alarmingly low vitamin D level of under 10ng/ml.

Over the next year, she traded excess cardiovascular exercise for strength training, switched to a gluten-free diet, and raised her vitamin D levels to an optimal range. Not only did she transform her body, but she also rarely gets flare-ups and is off all medications related to her autoimmune disease.

Another athlete I worked with was an NFL player whose career was in jeopardy when he came to me. Entering his fourth season, he had dealt with multiple ankle sprains, groin pulls, and a torn ACL during his young career. After only three seasons, he was considered injury-prone, a potentially career-ending label you absolutely do not want to carry around in pro sports.

Again, we began with blood work, which uncovered multiple food allergies and mineral deficiencies, including a vitamin D level of 18. After a long off-season working on improving strength imbalances, refining dietary guidelines, and increasing vitamin D levels, he became a starter for the New England Patriots and won a Super Bowl ring.

Figure Out Your Vitamin D Situation

Every athlete I’ve worked with who has experienced a vitamin D deficiency has realized significant improvements in performance, agility, and overall well-being by bringing his or her levels up. You can do the same by taking the following measures.

First, define your vitamin D levels. Before you can increase your vitamin D levels, you have to determine their starting point by having blood work done. This test will give you more than just a number; it can also reveal whether vitamin D deficiency is causing bone weakness or malformation or whether there’s a problem with the parathyroid gland that controls vitamin D activation. In addition to increased vitamin intake, your improvement might also require addressing polymorphisms that inhibit how your body absorbs vitamin D.

Like most of your essential nutrients, vitamin D can be found in many of the foods we already consider healthy. Be sure to include plenty of vitamin D-rich foods7 in your diet, such as fish, dairy or fortified non-dairy alternatives, grass-fed beef, and vegetables. However, don’t rely completely on food as your main source of vitamin D. Without enough sunlight, you might still be at risk of insufficient or deficient levels.

Vitamin D is called the sunshine vitamin because it can be generated by your body after you expose your skin to the sun. About 20 to 30 minutes in the midday sun at least twice a week is a good start, depending on where you live, your age, and your current vitamin D levels. If you live where the sun rarely shines brightly, you may need to adjust your diet, including taking supplements.

Adding recommended vitamin D supplements to your regular diet may not be a bad idea. Food offers a relatively small amount of vitamin D, and people who live in cloudy northern climates often have difficulty getting enough sun. To offset this disadvantage, many athletes rely on supplements recommended by a physician or dietician. The average recommendation is 2,000 international units (IU) to 10,000 IU daily,3 depending on age and current levels. In some cases, a bolus dose is optimal, meaning you divide your weekly dose (30,000 IU, for example) into two equal doses (15,000 IU each).

As our awareness of our bodies and what they need grows, taking things like vitamin D levels into account is becoming increasingly important. Athletes need nutrients for their bodies to perform, and those who invest in athletes know that poor levels could mean a risky investment. For both the love of the sport and the longevity of your career, make vitamin D intake a priority in your training regimen, and keep a close eye on how far your levels rise and fall.

Find out if your supplements are worthwhile:

The Fallacy of Supplements


1. Axe, Josh. “Vitamin D Deficiency Symptoms & Sources to Reverse It!” Dr. Axe Website, 2015.

2. Bachman, Rachel. “Elite Athletes Try a New Training Tactic: More Vitamin D.” The Wall Street Journal, 25 January 2016.

3. Group, Edward. “How Much Vitamin D3 Do You Need?” Global Healing Center, 5 October 2015.

4. Keller, Maura. “Vitamin D’s Impact on Falls.” Today’s Geriatric Medicine.

5. Lab Tests Online Editorial Board. “Vitamin D Tests.” Lab Tests Online, 22 September 2016.

6. O’Mara, Kelly. “The Link Between Vitamin D and Athletic Performance.”, 22 January 2016.

7. SELFNutritionData. “Foods highest in Vitamin D.” SELFNutritionData, 2014.

8. Shilstone, Mackie. “Optimum Performance: Coming to the Saints’ defense with vitamin D.”, 19 September 2013.

9. Spano, Marie. “Vitamin D – Why It’s Essential for Muscle Health!”, 28 May 2013.