Athletes and Vitamin D deficiency

And the synergy of vitamin D3 and K2

Written by: Joachim Bartoll, September, 2015
Classic Muscle Newsletter, Oct 2015


In 2012 I wrote an article about Vitamin D and its many benefits, especially when it comes to healing. At the same time I developed a vitamin D3 and vitamin K2 combined supplement for a Swedish company. I came up with this formula because a high intake of the active vitamin D3 will increase the concentration of calcium in your blood stream. This happens because your body will up-regulate the synthesis and repair of bones, ligaments and joints. Excessive calcium can lead to arterial calcification, but vitamin K2 reduces this buildup by increasing absorption where is needed. In other words, vitamin D3 and vitamin K2 work synergistically with each other to heal the body.

Another reason for developing a vitamin D supplement is that most people are deficient. The rate of vitamin D deficiency has gotten more and more attention in recent years, and is now estimated at greater than three-quarters of the general population. That’s more than 75 %! It’s therefore likely that many athletes fall into this same category. And if you live in countries with colder climates and less sun exposure, such as northern USA, Canada, Norway, Sweden, and so on, it’s even worse.

The reasons for this deficiency are that natural food sources of the vitamin are scant, with fat fish being one of the few. However, the amount of vitamin D contained in fish is relatively minuscule, and attempting to meet the nutritional requirement for vitamin D from fish, or any other food for that matter, is an exercise in futility. The most reliable source of vitamin D is actually exposure to ultra violet rays emitted from the sun.
However, it’s not as easy as being outside for an hour or two. For one, the sun has to be at a certain point in the sky to emit a wavelength of UV that is potent enough to activate the mechanism in the skin that produces vitamin D. Thus, at certain latitudes during the autumn, winter, and spring, not enough UV light is emitted by the sun at the optimal wavelength to produce vitamin D. Another problem is that those who are older, overweight, or black may not produce enough vitamin D even if exposed to the proper UV rays. Vitamin D is produced in the skin through interaction of UV rays and cholesterol in the skin layers. Having darker skin, or having a greater amount of subcutaneous body fat, blocks the UV penetration into the skin, so there is not enough vitamin D synthesis. The same holds true if a sunblock cream is used, which blocks UV penetration into your skin.

Resent research shows that vitamin D is only a nutritional precursor, a pro-hormone of sorts, to the more active form of vitamin D3 in the body. The vitamin D formed in the skin, or ingested from food or supplements, undergoes enzymatic conversion in the liver and kidneys to form the active D3, 25-hydroxy D. This form of vitamin D is known to interact with more than 1,000 genes in the body.
Most tissues and organs in the body contain vitamin D receptors. These receptors exist in the testes, where they are thought to play a role in testosterone production, as well as in the muscles. While the current research on the health effects of vitamin D are increasing by the day, preliminary evidence suggests that vitamin D favorably affects immune function, bone and joint repair, and also may play a preventive role against cardiovascular disease, cancer, and diabetes. But it's the effects on testosterone and muscle function that are of most interest to those involved in any type of exercise or sports activity. Therefore the obvious question is: Since most of the population is lacking sufficient vitamin D, what about athletes? Do they ingest enough to support muscle function and hormonal synthesis?

That was actually the objective of a recent study published in the Journal of the International Society of Sports Nutrition 2015. Vitamin D is important to athletes or those who exercise regularly because it does affect athletic performance and recovery via its potential impact on protein synthesis, muscle function, hormone synthesis, immune response, inflammation and regulation of lean muscle. So this study looked at the vitamin D status of a group of professional basketball players. Specifically, the levels of the active hormonal form of D were analyzed in 7 of the 12 players on the Canadian Men's Olympic Basketball Team. Collection of the players' blood began the day prior to the start of training camp, and again at the conclusion of the competitive season.

The results showed that of the seven players tested, only one showed optimal vitamin D levels (at 144 nmol/L), and he happened to be the only one ingesting a vitamin D supplement. Another player showed an outright vitamin D deficiency (at 1 nmol/L), while the others (with the exception of the supplemented player) showed less than optimal levels of vitamin D. The optimal level of D is considered to be at 100 nmol/L or above, as measured by blood testing. Anything 50 nmol/L or below is considered deficient and insufficiency is defined at the range of 50 to 80 nmol/L.
The mean serum of vitamin D for the seven players tested was 69 nmol/L, while the median score was 61 nmol/L. That’s a far cry from minimum healthy levels at 100 nmol/L or more.

To obtain the optimal blood level of active vitamin D requires either sun exposure of the whole body for a minimum of 15 minutes daily, assuming that the sun is in the right place in the sky, or ingesting a vitamin D supplement, which is the easiest way to meet the requirement. Since vitamin D is a fat-soluble vitamin, it's important to always ingest it together with a meal containing some fat, or using another fat source such as for example coconut oil or some fish oil together with the vitamin D. Ingesting vitamin D together with fat boosts absorption rate an average of 66%. Taking vitamin D with only water or with only carbs and/or protein is a total waste.

Even though the research related to any ergogenic effects of vitamin D is still young and limited, the fact that it plays such a vital role in immune response and other mechanisms important for sports and exercise, such as protein synthesis, prevention of bone stress fractures, and possible interactions with testosterone, mandate that those who want the best results from their training should ensure that they have optimal levels of active vitamin D. Unless you get that daily UV exposure, my recommendation is to get a good vitamin D supplement. If you want to be really sure, the best way to determine your vitamin D status is to get a blood test for levels of 25-hydroxy D. If you show low levels of active vitamin D, it would be prudent to consider a supplement. The best type of vitamin D supplement to use is vitamin D3, which lasts longer in the body than the other common supplemental form, D2.

For those aiming at optimal healthy levels, depending on how much time you can spend outside, a good starting dose is somewhere between 4,000 and 8,000 units a day. If you’re going for the higher dosage, please consider adding some vitamin K2.
If you’re interested in the healing abilities or the cancer fighting abilities of vitamin D and want to try high dosages in the 12,000 to 20,000 IE range, taking an additional vitamin K2 supplement is highly recommended.

The vitamin K2 should be in the form of K2-7 (MK7). The ideal relationship is a 1:1 ratio when measuring vitamin D in mcg. This means that 4000 IE of Vitamin D, which equals 100 mcg, should ideally be taken together with 100 mcg of vitamin K2. 3000 IE of vitamin D, which equals 75 mcg, should be taken with 75 mcg of vitamin K2 and so on.

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Go here for my article from 2012 about Vitamin D (only available in Swedish)

Observational case study - Vitamin 25(OH)D status of professional basketball players and its impact on athletic performance and recovery.
Marc Bubbs, Sports Nutrition Lead, Canada Basketball.
Journal of the International Society of Sports Nutrition 2015, 12(Suppl 1):P55  doi:10.1186/1550-2783-12-S1-P55