Believe it or not, Canadians have some of the lowest Vitamin D levels in the world with only 10% achieving the optimal level . Commonly known as the sunshine vitamin, Vitamin D is primarily absorbed through the skin. However at our elevation and longitude here in Calgary, the amount of time needed to spend with our skin exposed to the sun is far greater than most other places around the globe.
Not really a vitamin
Vitamin D isn’t technically a vitamin either. Vitamins are nutrients essential for sustaining life that are acquired through ingestion as they cannot be produced by the human body. As vitamin D can be absorbed through the skin then converts into a hormone (ultimately Calcitriol when combined with 7-dehydrocholesterol and processed through the liver and kidneys) for use in the body then it is not a vitamin by definition but more of a hormone precursor. Either way, the end product is a wonderful substance that is primarily responsible for enhancing intestinal absorption of calcium and phosphate which leads to stronger bones and teeth. It has also been linked to an increasing list of chronic health problems such as bowel and colonic cancer, arthritis, diabetes and cardiovascular disease.
What are the best sources?
Despite our geographical disadvantage, exposing your skin to the sun is still the most effective means of acquiring vitamin D (specifically, vitamin D3), especially during the noon hours when the UV index is at its peak. Because this is unfortunately impractical for a number of us, we must resort to foods and supplements to complete our recommended daily allowance (RDA). Egg yolks and fatty fish like salmon, mackerel, sardines and tuna are the only foods that naturally contain vitamin D (specifically, vitamin D2), all other common sources such as cow’s milk, infant formula and other beverages have vitamin D added (D2/D3). Even though these are reasonably good sources, it is likely that you will need to supplement with vitamin D which is easily done through pills, gels or liquids.
How much do I need?
The most accurate measure of vitamin D in your body is through blood work where the recommended volume of 25(OH)D is 100-150nmol/L . This can typically be achieved by consuming between 1500-2000 IU per day (adult). Check the nutrition table on your vitamin D-fortified foods to calculate your intake or use an app such as www.dminder.info .
How Much is Too Much?
Upper limits (UL) for vitamin D vary quite a lot amongst the various institutions (between 4,000 and 10,000 IU) however the most consistent UL rest at around 1000 IU for infants, 2500 IU for children and 4000 IU for adults, including pregnant and lactating women .
Vitamin D and Testosterone
A widely-cited study conducted by a team from the Department of Internal Medicine at the Medical University of Graz, Austria (coincidentally the birthplace of Arnold Schwarzenegger), identified a significant increase in the amount of total, bioactive and free testosterone in a group of male subjects dosed with 3,332 IU of vitamin D per day for 1 year versus a placebo group which experienced no change . Testosterone is vital for many daily functions in males and significant in supporting resistance and athletic training as well as sexual health.
Those most at risk of being deficient
The benefits of adequate vitamin D intake and the potential risks of being deficient extend beyond bone and dental health so it is important to know if you are at risk. A receptor recently identified in most tissue and cells in the human body adds credence to the argument for Calcitriol affecting a wide range of genetic and muscular functions. Those most at risk of complications arising from inadequate consumption are infants exclusively breastfeeding (breast milk is naturally low in vitamin D), adults over 50 (the skin becomes less adept at absorbing vitamin D from the sun), those with skin darkly pigmented with melanin (the skin is less able to create vitamin D from sun exposure), and those with medical conditions that affect the cells and organs e.g. Crohn’s, cystic fibrosis and celiac disease.
Too manageable to overlook
Although the upper and lower limits vary, the common thread is that we are almost universally deficient in our consumption of a vital nutrient that is very easy to address. A quick search of online pharmacies yields prices as low as $5 for a 3 month supply (2000 IU/day). With this level of accessibility and a low propensity for negative side effects, supplementing your diet with adequate levels of vitamin D makes too much sense to ignore. Get your sunshine today!
Strength & Conditioning Director
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