Daylight Savings may be in full swing, but that doesn’t mean your stores are as high as they should be.
by Pip Taylor
If you live in the northern hemisphere you are likely enjoying some off-season time and embracing—or simply enduring—colder weather. Bare skin and sunshine might be a distant memory, but this lack of outdoor time might be affecting more than just your training hours and your mood.
We can obtain small amounts of vitamin D from our food, but sunlight is our main source—hence the nickname the “sunshine vitamin.” This fat-soluble vitamin (which actually functions as a hormone within our bodies) has enjoyed plenty of attention from researchers over recent years. Deficiencies are linked with a broad range of maladies, while adequate supply is credited with keeping us happy and healthy in countless ways.
D in action
There are receptors in almost all body tissues for vitamin D, suggesting just how important it is in so many areas of our health. It plays an important role in bone health (by regulating calcium and phosphorous homeostasis), it is essential for gene expression and cell growth, as well as nerve signaling, muscle function, and optimal body composition. It helps reduce the risk of certain cancers and boosts mood and brain function. Depression and anxiety levels also decrease when adequate levels of the vitamin are restored in deficient patients.
Who needs it?
Athletes need consistent training in order to see performance gains. To this end, vitamin D can help increase immunity, recovery and bone strength, while decreasing inflammation—all factors that help curb illness and injury. There is also emerging evidence that supplementing vitamin D in athletes with suboptimal levels can help increase strength, power, reaction time and balance.
Recent research suggests that even in countries, states or regions with plenty of year-round sunshine such as Australia, the Middle East, Hawaii and Texas, vitamin D deficiency is prevalent. Even throughout summer if you regularly work out in the early morning, evenings (religiously cover up and wear sunscreen) or indoors, then you may not be getting enough sunlight to manufacture vitamin D. Dark, cold winters exacerbate deficiencies, which also increase with age and are more common among women than men. If you have a history of bone fractures or have impaired absorption (such as Crohns or Celiac disease), you are also at an increased risk of vitamin D deficiency. Some medications can decrease vitamin D activity, so its important to discuss this with your doctor.
You can get your levels tested with a simple blood test. It’s worthwhile talking to your doctor, particularly if you live somewhere where you don’t get a lot of sunlight, or if you meet any of the other risk factors mentioned above. Currently, clinical vitamin D levels are defined as follows:
-deficient (<20 ng/mL)
-insufficient (20 to 32 ng/mL)
-sufficient (>32 ng/mL)
Higher levels are sometimes recommended for athletes for health and performance reasons.
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The principal source of vitamin D comes from exposure to ultraviolet B (UVB) radiation from sunlight. Certain foods such as egg yolks, oily fish, liver and fortified foods contain small, but not adequate, amounts. Sunlight is a reliable source, but athletes need to be careful not to overdo exposure, which holds its own risk of skin damage, premature aging and skin cancers.
Your latitude and the time of year will determine the recommended amount of exposure to sunlight required to meet adequate vitamin D levels. If you choose to supplement, vitamin D3 is the preferable form. (An intake of greater than or equal to about 1000 IU may be needed for most of the population.)
Pip Taylor is a nutritionist and professional triathlete.