Sports Medicine

Vitamin D for Athletic Performance and Health

Vitamin D in Athletes is by all means not a new concept. Lets look at the history and research of Vitamin D in athletic performance, and then I will also share my experiences and recommendations for diagnostics and dosing.

The ecological logic of Vitamin D 

As we know Vitamin D is a substance that can be produced by our own body, when it is subject to UV-B radiation from the sun. To get adequate levels of Vitamin D from the sun not only the total minutes of exposure are important, but also the angle of the sun rays as they hit the earth. It is fairly straight forward to understand that the sun has more „power“ where it hits the earth in a perpendicular angle. You know that you get a faster sunburn when you lie on a beach around the equator, compared to lying on a beach in Sweden. The same holds true for Vitamin D production. We need a lot more sun exposure the further we live away from the equator. And thats a logical problem, because the further we get away from the equator the colder it gets. This makes it harder to expose our skin to the sun. Also, the further we get away from the equator the less sun exposure there is in the winter. 
As Vitamin D is such a vital substance, the question arises then how humans were able to survive in areas where there is limited sun exposure. How did humans get adequate levels of Vitamin D, when they lived in Siberia, Scandinavia, Alaska, the Falkland Islands, or even Southern Australia?
The answer is as fascinating as it is simple. We can also get Vitamin D from the fat of animals, especially from the fat from fish. And the colder the water, the more fat a fish carries. Where there is a lot of sun, the fish are skinny, without relevant amounts of Vitamin D, but where there is no sun, the fish are fat and contain a lot of Vitamin D. Mother Nature took care of our Vitamin D needs. 
Sunshine Calendar Vitamin D around the world
Now a problem arises, when we neither get enough sun, nor enough fats. And hence we have such an epidemic of Vitamin D deficiency, with an estimated 1 billion people worldwide, 50% of the people in Europe, up to 64% of athletes, and 84% of professional football players being deficient in Vitamin D.
In my experience of testing athletes I estimate around 80-90% of athletes, who do not supplement Vitamin D, are moderately to severely deficient in Vitamin D.

Vitamin D Deficiencies around the world. 

In Phoenix, Arizona, one of the sunniest cities in the world, most of the population is Vitamin D deficient. Thats because the average Arizonian does not spend much time outside. Only the roof workers in Arizona have high and sufficient levels of Vitamin D.
A more extreme example of this is the high prevalence of Rickets around the equator. Rickets is a severe Vitamin D deficiency resulting in bone deformation, sleep disturbance and intellectual disability. This disease happens a lot to children in Africa, because they spend so much daytime in the shade of the huts, and only leave the huts when the sun went down. 
When I worked in Qatar I was blown away that they have a massive Vitamin D deficiency problem. They have a severe health crisis with Diabetes and osteoarthritis, which could at least in parts be attenuated by adequate Vitamin D levels, but the average Qatari has severely deficient levels of Vitamin D, because they are tightly wrapped up in their traditional clothing and they spend a large portion of their day in the shade.
Research has shown that between 50-64% of athletes are deficient in Vitamin D. A study found that 84% of professional soccer players are deficient in Vitamin D, with 12% being severely deficient. 
In the 2010 NFL season 81% of the players on the New York Giants roster were deficient in Vitamin D.
Professional Athletes training in the sun
ALLOUT Coaches working with Icehockey Goalies out in the sun

Reasons for deficiency

There is preliminary mechanistic evidence that our bodies need for Vitamin D has risen sharply since the industrial revolution. Vitamin D is necessary to attenuate the negative effects of Smog, environmental toxins, stress, elektrosmog, and suboptimal water and food quality. 
On the other hand the input of Vitamin D is reduced since the 1970’s when government health agencies mistakenly warned about the health dangers of consuming too much animal fats. Vitamin D is found in animal fats and it is necessary to consume large quantities of fatty fish to compensate a lack of sunlight exposure.
An underestimated factor is that Magnesium is a necessary nutrient for our ability to store Vitamin D. So as Magnesium levels in the population drop because soils and plants are becoming more and more Magnesium depleted, also the Vitamin D levels suffer. Just in February of 2018 a new study showed that with adequate Magnesium levels we need much less Vitamin D from outside sources to bring our Vitamin D levels to an optimum. If our Magnesium levels are not good, then Vitamin D cannot be as effective and safe. When somebody starts supplementing with Vitamin D and starts to get sleep problems thats a definite indication that the Magnesium levels are too low. Also when somebody supplements Vitamin D in high doses, but his levels do not seem to rise. First bring up the Mg levels, then the D levels.
Athletes preparing food
My team working with athletes on their food preparation

UV-Radiation in High Performance

Already Back in the 1920’s we Germans put our German swimmers under UV-lights several times per week. Germany did a lot of research on UV-radiation and athletic performance at that time. The benefits were so great that there was a big discussion if UV-radiation should be regarded as doping.
Some experts argue that the Olympic Games in Mexico in 1968 brought forth so many olympic records that held for many many years, because the athletes had excellent Vitamin D levels, as Mexico City is close to the equator and at a slightly higher altitude.
A randomised controlled trial from 1944 showed that UV-radiation only twice weekly could improve aerobic endurance by 13% in only 6 weeks.
Other studies on elite athletes, some from the Sporthochschule Köln, showed that regular UV-radiation :
  • Reduced chronic injuries by 50%
  • Improved reaction times by 15%
  • Improved adaptive capacity (athletes with radiation recovered and improved faster than controls)
  • Improved 100m sprint times up 7,4% (Russian randomised controlled trial)
At that time not only elite athletes underwent UV-radiation. Among mothers it was a trend to send their kids to UV-radiation a couple of times per week. 

Vitamin D as the main benefit of sunlight

Research soon discovered that the benefits of UV-radiation are mainly due to its effects on Vitamin D production. They compared the effects of UV-radiation with the effects of isolated Vitamin D therapy. 
A study from 1952 looked at the effects of UV-radiation vs. 250.000 international units (IU) of Vitamin D in 30 school kids. It turned out both groups had similar results in measures of aerobic endurance.
UV sunlight Vitamin D research
As a result of studies like these the science switched to research the effects of isolated Vitamin D supplementation as compared to UV-radiation. After many positive benefits were discovered a base supplementation regime for children was implemented nationwide in many European nations. 
Children in Finland got a daily dose of 4000IU of Vitamin D up until 1964. Either Vitamin D capsules or cod liver oil was being used for that purpose. I remember my grandma giving me daily doses of cod liver oil, because „its good for my boy“.
In Germany daily doses of cod liver oil for kids was usual up until the 1980’s.
I did not exactly find out WHY Finland and Germany stopped recommending Vitamin D. There are many  loose theories out there that have something to with Big Pharma conspiracies, but I dont want to go down that road without any hard evidence. 

Are optimal Vitamin D levels necessary for optimal performance?

A study from 2011 showed that testosterone levels rise by 30% when the Vitamin D levels go up from 30ng/ml to 60ng/ml.
A randomised controlled trial from 2013 showed that soccer players from the Liverpool Academy who supplemented 5000IU Vitamin D daily improved their sprint times by 2,7% and their jumping height by 7,6% compared to controls.
NFL players who got released before the start of the season on average have lower Vitamin D levels, than players that earn a contract. That correlation is actually true, but to conclude the role of Vitamin D in NFL performance is far fetched to be honest. 
According to Dr. Ray Matthews, a leading Vitamin D expert, adequate Vitamin D levels will dramatically reduce the individual chance of brain trauma. That is because Vitamin D increases the production of heat shock proteins, which make the brain more resistant to heat, cold, and trauma.
Not only has research shown that adequate Vitamin D levels are associated with lower rates of injury, but it has also been shown mechanistically that Vitamin D will improve healing times of muscle tissue.
Systematic meta-analyses from 2014 showed that Vitamin D supplementation improved strength in the upper and lower extremities and further studies showed that fast-twitch fibre hypertrophy is improved when Vitamin D levels are adequate.

Are optimal Vitamin D levels necessary for optimal health?

EVERY single cell in the human body has a receptor for Vitamin D. That is why Vitamin D has so many wide ranging benefits. 
A meta-analysis with 849.412 participants has shown that the risk of dying from cancer or heart failure is significantly reduced if the Vitamin D levels are adequate.

Disease incidence Vitamin D Levels


EVERY single cell in the human body has a receptor for Vitamin D. That is why Vitamin D has so many wide ranging benefits. Klick um zu Tweeten


Vitamin D plays a key role in the immune system. Not only can minor infections be reduced with adequate Vitamin D levels, but adequate Vitamin D levels also protect from auto-immune disease. Vitamin D has been positively associated with the outcomes of multiple sclerosis, inflammatory bowel disease, and even ALS (thats the Stephen Hawking disease). 
Some experts even go as far as saying that developing an auto-immune disease is simply not possible with adequate levels. (Even though to my knowledge there is no hard evidence to support this statement)

MS prevalence around the world


What are optimal levels of Vitamin D?

Farmers or Life guards at the beach have Vitamin D levels around 50-70ng/ml.
Effects of improved performance are evident up until around 60ng/ml. Anything above 70ng/ml is not really associated with added benefits. Some studies even show that above 70ng/ml the effects are actually reduced.
Many labs used to recommend 30ng/ml as adequate levels. And as doctors usually base their recommendations on the lab values, most doctors used to recommend an optimal level of 30ng/ml.
When I first worked intensively with Vitamin D around 2010, most doctors and labs were very restrictive with Vitamin D levels above 30ng/ml. 
Nowadays the government organisations, labs and doctors caught up to the research a bit and some labs now recommend optimal levels between 50-70ng/ml.
I am aiming for 60ng/ml with myself, my athletes and most of my patients.
 Biochemical connections

The optimal dosing of Vitamin D

Vitamin D can theoretically be overdosed. In practice I have never seen an overdose, even though I have worked with single doses of up to 1.000.000IU and regular doses of up to 500.000IU per week for many weeks. 
Like cited earlier, in the 1950s they did studies with children who received doses of 250.000IU.
Current research could not find any signs of overdosing with 160.000IU per week.
The endocrinological society of the United States has classified a dose of 50.000IU per week in people with low levels as „generally regarded as safe“. The standard therapy of most medical professionals is 20.000IU – 40.000IU per week in deficient patients. I consider that a bit too low to achieve adequate levels.
Studies from 2014 showed that a maintenance dose has to be north of 2000IU per day. A dose to increase the levels has to be at least 5000IU per day. A study from May 2015 even recommends a daily maintenance dose of 8000IU, because only a dose that high makes it possible to reach adequate levels. With this research they are correcting a mathematical error from an earlier study that lead to the universal recommendation of 600IU per day. They simply miscalculated it by around factor 10.
Looking at the sum of the current literature any recommendation below 3000IE to improve Vitamin D levels is far outdated.

Here is a supplementation protocol I have been using :

<10ng/ml : 100.000IU, 2x/week for 8 weeks – then re-measure
10-30ng/ml : 60.000IU, 2x/week for 8 weeks – then re-measure
30-50ng/ml : 40.000IU, 2x/week for 8 weeks – then re-measure
>50ng/ml : maintenance dose : bodyweight x 200, 2x/week
This is a general rule of thumb. As I mentioned earlier it is highly dependent on the individuals functional state how much of a dose is necessary to get in the optimal range. Especially Magnesium status plays a big role. Supplementing Vitamin D with inadequate Magnesium levels is like filling up a bucket with a hole at the bottom. That is why I recommend checking for Magnesium deficiency and re-evaluationof D levels every 8 weeks (in the beginning) to find the right dose.


In my experience adequate Vitamin D input is a very low hanging fruit when it comes to improving performance. Getting more time in the sun, eating more fatty fish, or supplementation with Vitamin D are easy strategies that go a long way. Vitamin D diagnostic and supplementation are really cheap. We were able to supply a whole icehockey team with adequate Vitamin D supplementation for a full year for under 500€. Depending on the individual needs, supplementation prices range from 10-90€ per year.
Vitamin D plays a huge role in recovery as it is a key player in the synthesis of testosterone and managing inflammation. (Chronic) Inflammation is the opposite of recovery and performance development, so making sure Vitamin D levels are adequate are a precursor to developing ones full potential.
Usual results I have seen with athletes who upped their Vitamin D levels are improved mood and confidence, improved strength levels, sudden drops in body fat, and improvement of skin condition. Everytime I work with pro athletes or teams, testing Vitamin D levels and ensuring optimal supply of Vitamin D is one of the primary considerations.
May the FLOW be with you!
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Tags : athletic performanceauto-immune diseasecod liver oildepressioninflammationmoodperformance docperformance medicinerecoveryregenerationstrengthUV-BUV-radiationvitamin d

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