I hope this is the one MD!
DR. D’S ELITE PERFORMANCE NEWSLETTER
Volume One, Issue One, December, 2009
Vitamin D and Athletic Performance
Vitamin D is More Than Just for Strong Bones
Not too many years ago vitamin D wasn’t considered all that vital beyond helping calcium challenged people, especially women who were or had a tendency toward osteoporosis, and of course to prevent rickets, something rarely seen in industrialize countries since even minimal amounts of vitamin D prevents severe deficiency.
As such, when most people hear about vitamin D they think of sunshine and bones. That’s because it’s common knowledge that exposure to the sun results in the formation of vitamin D and that vitamin D is important, along with calcium, for strong bones.
While that aspect of vitamin D is important, there’s a lot more to the vitamin D story.
Vitamin D is really a group of fat soluble prohormones called secosteroids. Thus, unlike most other vitamins, vitamin D is really a steroid hormone that the body uses to manufacture calcitrol (1,25-Dihydroxycholecalciferol), which is the active form of vitamin D in our bodies.
The two major forms of the vitamin obtained from sun exposure, food, and supplements are vitamin D2 (or ergocalciferol) and vitamin D3 (or cholecalciferol). Cholecalciferol is the vitamin D produced in humans by exposure to the sun, and is felt to be more effective than ergocalciferol for enhancing calcitrol levels in our bodies.
Recent research however, show that vitamin D is crucial for many functions in the body, and is crucial for many internal cellular processes, insulin production, the immune system, depression, heart disease, pregnancy problems, birth defects, skin and other cancers, and other diseases, including inflammation in the body from various sources, including aging.
For example recent studies have found that low serum vitamin D levels were associated with all-cause mortality, cancer, and cardiovascular disease mortality.
As a measure of just how important it is, it’s felt that possibly up to 2,000 different genes, which represents about one-sixth of the human genome, are affected by vitamin D.
Why Most of Us May Be Vitamin D Deficient
Vitamin D deficiency is increasingly being recognized as a worldwide epidemic. According to various reports experts believe that up to 3 out of every four adolescents and adults are vitamin D deficient, which is generally defined as having blood levels of less than 30 ng/mL.
For your skin to make enough, you'd need direct midday summer sunlight on a large portion of your body for around 15 minutes a day. If you live north of Atlanta, it's impossible to get enough D from sunlight between October and March, no matter how exposed you are. And it's tougher for people of color to make vitamin D — the melanin in dark skin decreases
vitamin D production by up to 90 percent
Although it seems logical to assume that people in high altitudes would not be deficient in vitamin D given that the ultraviolet light intensity is higher at high altitudes resulting in a greater vitamin D3 synthetic rate, the opposite is actually the case. The reason for this is likely that at higher altitudes the cooler weather involves using more clothing and less sunbathing.
Declines in vitamin D occur over the winter, with the level of decline, without conscious efforts to expose yourself to adequate sunshine or tanning UVB rays and without supplementation, is dependant on the level of vitamin D at the beginning of winter. So the more you’re able to maximize your vitamin D storage levels, the more you’ll be left with by the end of winter. However, if you rely on your summer acquired stores of vitamin D, and because winter can last several months, somewhere along the line you’ll develop vitamin D deficiency.
Much of the decline during winter months, and for those who don’t get a lot of sunlight during the summer, is due to the lack of vitamin D in the food we eat. Only certain kinds of fish and some fortified foods such as dairy and orange juice have significant amounts of vitamin D (see list below), and it would be hard to consume enough of these every day to get 1,000-plus IU.
And it’s possible that even those who seem to get lots of sun, because of variable responsiveness to UVB radiation may be vitamin D deficient (see full paper and abstract below - Low vitamin D status despite abundant sun exposure).
Vitamin D is Vital for Exercise Performance
The effects of vitamin D on performance have been known for decades. Back in the 1950s a number of German studies alluded to the beneficial effects of vitamin D on athletic performance (for example, Seidll E, Hettinger T. Influence of vitamin D3 on strength and efficiency of healthy adults. Int Z Angew Physiol. 1957;16(5):365-72.). As well, it’s well known that physical and athletic performance is seasonal in that it follows levels of vitamin D, peaking when it peaked and declining as vitamin D levels declined.
Vitamin D also increases the size and number of Type II (fast twitch) muscle fibers. Most cross-sectional studies show that 25(OH)D levels are directly associated with musculoskeletal and physical performance in older individuals.
But it’s not just the performance of older people that are affected by vitamin D deficiency. A recent review concluded that “Accumulating evidence supports the existence of a functional role for vitamin D in skeletal muscle with potentially significant impacts on both the performance and injury profiles of young, otherwise healthy athletes.” Other studies have shown that low vitamin D is a contributory factor in stress fractures in athletes.
Another recent review (Athletic performance and vitamin D. - Cannell JJ - Med Sci Sports Exerc - 01-MAY-2009; 41(5): 1102-10.) concluded "Most cross-sectional studies show that 25(OH)D levels are directly associated with musculoskeletal performance in older individuals. Most randomized controlled trials, again mostly in older individuals, show that vitamin D improves physical performance. CONCLUSIONS: Vitamin D may improve athletic performance in vitamin D-deficient athletes. Peak athletic performance may occur when 25(OH)D levels approach those
obtained by natural, full-body, summer sun exposure, which is at least 50 ng x mL(-1). Such 25(OH)D levels may also protect the athlete from several acute and chronic medical conditions."
How Much Vitamin D Can We Take?
Vitamin D is fat-soluble, which means it stays in the body for longer periods of time as opposed to the water soluble vitamins such as vitamin C.
This is good because it takes a longer period of time to become deficient if you start off with healthy levels in your body. For example if you build up vitamin D over the summer then there’s less chance you’ll be come deficient over the winter as long as you take in some vitamin D by eating foods high in vitamin D, take vitamin D supplements or expose your skin to artificial ultraviolet light.
It’s also bad in that if you take too much it can accumulate in the body and can cause toxicity. However, this aspect of vitamin D has been overemphasized in the past as it was thought that vitamin D accumulated and stayed in the body much more than it actually does.
Vitamin D doesn’t stay in the body forever as it is broken down continually by the body and disposed of. Vitamin D stored in the body has a half life of only three or four weeks, and this half life shortens with higher vitamin D levels. Exposure of skin to direct sunlight can produce up to 25,000 IU of vitamin D. However, when vitamin D gets to a certain level, any further vitamin D that is produced is degraded.
That means that the body can degrade and lower vitamin D levels in the body if it has to and thus can handle a lot more vitamin D than was previously thought. That doesn’t mean that our bodies can handle a lot more than previously understood, and that you can’t overdose on vitamin D and develop some counter productive and health damaging toxicity.
However, in my opinion it would take over 10,000 IU per day for several months before you would overwhelm the body’s ability to degrade excess vitamin D and produce more than physiological levels.
How Much Vitamin D do Athletes Need?
With sun exposure, pre-vitamin D3 is rapidly converted in the dermis to vitamin D3 (cholecalciferol), before its subsequent conversion to 25-hydroxy vitamin D [25(OH)D] in the liver. Further hydroxylation of 25-hydroxy vitamin D to its active form, 1,25 hydroxy vitamin D (1,25(OH)2D), occurs in the kidney
However, while the active form of vitamin D may be normal in the blood, the lack of reserves in the form of 25(OH)D is the actual measure of vitamin D reserves in the body and is used as a measure of vitamin D deficiency. Besides being a better marker of overall D status, it is the marker that translates best with the overall beneficial effects of vitamin D.
The basis for figuring out how much vitamin D that any one individual needs can be casually stated (such as a suggested range of vitamin D intake) or can be more precise depending on the tools we use. For precise determinations we need to know just what the present state of any individual is by getting a serum 25(OH)D level. From this level we can figure out just how much vitamin D is needed on a daily basis in order to achieve a desired vitamin D level in the body.
For example, if your 25(OH)D level is OK, and for optimal levels it should be between 50 and 70 ng/mL (for nnmol/L multiply by 2.5 – so 50 ng/mL would be 125 nmol/L – see
Conventional units to SI units - conversion factors.), then you’re in the right range and to stay there you should get between 1,000 and 2,000 IU of vitamin D per day.
If you’re below 50 ng/mL then you need to top up first and that might require 5,000 to 10,000 IU for several days to weeks depending on how low your levels are. If for example they’re below 20 ng/mL then I would suggest you take 10,000 IU for at least a month and then your levels checked again to see if you should continue at that level or go to maintenance levels of between 1,000 to 2,000 IU per day.
How you get the required amounts of vitamin D is up to the individual and his or her circumstances. For those with access to full UV-B sunshine, a half hour a day of near full body exposure (be careful to build up slowly and not get sunburned) will go a long way to giving you the necessary amount of vitamin D.
As well, eating food high in vitamin D is also an option although to get enough (unless you’re unbelievably fond of fatty fish and liver oils, and even if you are fond of cod and other fish liver oil you have to make sure you don’t overdo the vitamin A that these oils also contain), you will likely have to combine the dietary intake with sun exposure and/or vitamin D supplements.
If you feel that you can’t meet your requirements through a combination of sun exposure and food, then the use of vitamin D in the form of supplements, ideally as cholecalciferol or vitamin D3, is the easiest, cheapest, and safest way to make sure you're covered.
To make sure that they stay in the optimal vitamin D zone I recommend that athletes take in between 1,000 IU up to 2,000 IU, a day in the form of supplements. This amount will insure that
your vitamin D levels stay where they should be and also insure that you don’t run into any toxicity, no matter how long you take that level of vitamin D.
Conclusions and Recommendations
First of all it’s important to get your 25(OH)D blood level measured to see just where you are as far as your long term vitamin D intake. Once you have the initial measurement and make any changes that need to be made as far as daily vitamin D intake, you should have your 25(OH)D level check as needed until you’re above 50 ng/mL, and then once it’s relatively stabilized get it done at least once a year just to make sure you’re not developing a deficiency.
Although this process takes some effort it’s important for all athletes who want to maximize natural performance. At the same time a number of other blood tests can be done that will point out other problems and deficiencies. I’ve copied below the screening protocol I suggest athletes have done. If money is tight then the bolded tests are the ones that are absolutely necessary, while the others can be done as finances permit.
Don’t hesitate to get some full sun exposure every day. The sensationalistic naysayers and purveyors of skin cancer with any amount of sun exposure should be ignored. Reasonable, and controlled levels of daily sun exposure to your body is not something to avoid but something to be sought as it has significant health benefits as long as sunburn is avoided and there are no medical contraindications such as the presence or predisposition to skin cancer and interactions with some medications.
Regardless of sun exposure and foods eaten, take between 1,000 and 2,000 IU of supplemental vitamin D every day. If your vitamin D levels are low then take more until you’re at a level that you feel comfortable with, at least above 50 ng/mL, and then maintain by talking supplemental vitamin D as above.
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