Micronutrients: Vitamin D
If you’re just joining me this month, I’m spending some time addressing five of the top nutrient deficiencies in athletes and exercisers. We spent the last 2 weeks addressing both magnesium and calcium deficiencies and this week, we’re talking about vitamin D.
Like many, if you are an athlete who spends time recreating outdoors, you might suspect that your vitamin D levels are adequate.
Maybe. But maybe not.
The latest research being done on vitamin D levels and sports performance is finding that athletes, even those that regularly workout outdoors, have vitamin D levels that are comparable to those of the general population (aka- low).
Vitamin D is known as the sunshine vitamin. It is a fat soluble vitamin whose main role is to help the body absorb calcium, magnesium and phosphate through the intestines.
For decades, we have known vitamin D’s role in bone health, but in the last decade, more and more research is being done on vitamin D and the science is finding the importance beyond just bone health.
For example, the evidence is showing that vitamin D also plays a role in:
In plain English, all things that affect sports performance!
Vitamin D has been shown to improve muscle mass and strength, accelerate the recovery of muscles from intense exercise, prevent muscle degeneration, improved oxygen exchange in the lungs, and improve the structural remodeling of cardiac muscles.
A meta-analysis completed in 2011 that grouped together 23 different studies and was composed of 2313 athletes found that 56% had insufficient levels of vitamin D!
So please don’t assume that just because you regularly workout outside, that you are vitamin D sufficient. Read on to learn more about testing so you can find out exactly what your vitamin D levels are and take action, if needed.
SIGNS OF DEFICIENCY
The most common symptom of a vitamin D deficiency is muscle pains.
It is not uncommon for people with vitamin D deficiencies to have musculoskeletal pains that are misdiagnosed as fibromyalgia or chronic fatigue syndrome.
Muscle strength, or lack thereof, can also be a sign of a vitamin D deficiency.
Two separate studies from 2011 and 2013 found that low vitamin D levels were negatively associated with muscle strength markers.
That means that the lower the vitamin D levels, the weaker the muscles!
The main risk factors for a vitamin D deficiency are cultural and environmental.
Because the majority of our vitamin D is obtained via sun exposure, things like atmospheric pollution (which decreases the UVB rays from reaching the Earth's surface), the use of sunscreens, latitude, weather and lifestyle will all affect our vitamin D levels.
Athletes who have darker skin are also at a higher risk for a vitamin D deficiency since the pigmentation of the skin can block UVB rays from reaching the skin cells.
One study showed that athletes with darker skin need up to 10 times longer exposure to UVB radiation to obtain the same levels of vitamin D as lighter skinned athletes.
25(OH)D, also known as 25-hydroxyvitamin D is a serum (aka - blood) test and is the current gold standard for testing vitamin D status.
This test was developed in 2017 and measures the concentration of unbound vitamin D which is the biologically active form that can pass through the cell membrane and actually carry out its intended function.
This test also measures vitamin D obtained from all sources (sun, food and supplements).
Protein bound vitamin D levels can also be measured by a blood test.
However, the issue here is that your body can have a problem converting the bound vitamin D to unbound vitamin D. If that is the case, and you only measure the protein bound vitamin D levels, you may get a “normal” result but still have inadequate active vitamin D., but if there is dysfunction in the unbinding process, this test will be irrelevant.
When getting a vitamin D test done, you should refer to the functional 25(OH)D range for optimal vitamin D which is between 30-40 ng/mL.
Since levels of vitamin D are highly affected by sun exposure, I highly recommend all athletes get their vitamin D levels tested twice per year.
One time in the winter and again in the height of summer.
These results will be suggestive of your high and low levels of vitamin D throughout the year and can be used to put together a proper supplementation protocol specific for your body.
There are two biologically inactive sources of Vitamin D: Cholecalciferol, or vitamin D3 and Ergocalciferol, or vitamin D2.
Once obtained in the body, both forms must undergo activation within the liver and/or kidneys to be biologically available to our tissues (this is the process I referred to earlier that people may not realize is not working properly. This is why it is important to measure your free or unbound vitamin D levels).
The main source of vitamin D obtained by humans is vitamin D3.
It is created endogenously, primarily through the interaction of sunlight (specifically UVB rays) with our skin. However, a very small amount of vitamin D can also be obtained exogenously through diet.
Consuming adequate levels of vitamin D through the diet is difficult because very few foods contain it naturally. The exceptions are:
Traditionally, many people obtain vitamin D through foods that have been fortified with it, such as milk, breads, and cereals.
Since the majority of vitamin D is synthesized in your skin from UVB rays, it is important to address any vitamin D deficiency with lifestyle first.
Getting out into natural sunlight without sunscreen or clothes that cover your skin for a short time each day is the best way to increase your vitamin D naturally.
If lifestyle changes still don’t increase your vitamin D levels, and you are consuming foods rich in vitamin D regularly, it may be time to consider supplementation.
The recommended daily allowance of vitamin D for adults ages 19-70 years old is 600 IU daily.
However, testing is critical before supplementation.
Excess vitamin D intake can increase your risk for soft tissue calcification. And for many, 600 IU of vitamin D will not be adequate to bring their vitamin D levels into a functional range.
Keep in mind that like all micronutrients, vitamin D status is not independent to itself.
Calcium levels, sun exposure and inflammation will all have an effect on your vitamin D levels and need to be addressed if vitamin D status is low.
When supplementing with vitamin D3, one should look for a supplement that also includes vitamin K. Like vitamin D, vitamin K is also a fat soluble vitamin. It is found naturally in leafy greens, fermented vegetables, egg yolks, liver and cheese.
Vitamin D and vitamin K work together in the body as a team.
Vitamin D ensures that your blood levels of calcium are adequate, however, it does not control where the calcium ends up within the body. That is the role of vitamin K.
Vitamin K promotes calcium accumulation in the bones, and reduces the risk of calcification of calcium in the soft tissues, such as your kidneys and blood vessels.
My favorite vitamin D supplement is made by Designs for Health and is called Vitamin D Supreme. Just remember, before just ordering and taking any ol’ vitamin D supplement, test your levels first and consult with your medical provider over the results.
With a growing body of evidence that supports having an adequate level of vitamin D in athletes to not only to sustain normal health, but also to positively impact athletic performance, it is critical that all athletes test their levels.
Given the evidence of high incidence of vitamin D deficiency, the relatively few sources of vitamin D in the food supply, and the environmental factors that limit an athlete’s ability to synthesize vitamin D, proper supplementation may become one of the most essential parts of an athlete’s nutrition protocol.
If testing and crunching numbers isn’t your thing, set up a free discovery call to talk to me about how I can help you look at not just your vitamin D status, but how all of your blood markers are working together to create optimal health for you.
1) Role of Vitamin D in Athletes and Their Performance: Current Concepts and New Trends, Nutrients. 2020 Feb; 12(2): 579. Published online 2020 Feb 23
2) Forrest K.Y., Stuhldreher W.L. Prevalence and correlates of vitamin D deficiency in US adults. Nutr. Res. 2011;31:48–54. doi: 10.1016/j.nutres.2010.12.001.
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Tiana Rockwell is a certified nutritional therapist, avid endurance athlete and dark chocolate lover. She believes that by eating REAL food, we can balance our body and reach optimal health and wellness!