Vitamin D: The Sunshine Vitamin

November 1, 2008

By Anna Varriano

As November marks the end of Daylight Savings Time, I thought it appropriate to write about the “sunshine vitamin” – vitamin D.

Vitamin D has been getting a lot of attention lately and rightfully so. Based on recent research, it may very well be one of the most important foundations for creating and maintaining good health. Mother Nature must think so too, as our bodies have a built in mechanism to manufacture vitamin D. Some researchers claim that ongoing studies will show that getting enough vitamin D is just as important to health as quitting smoking is.

Vitamin D is often referred to as “the sunshine vitamin” due to the fact that sunlight, even on a cloudy day, is the most natural way to ensure the body gets vitamin D. Exposing our skin to sunlight (specifically the UVB rays) initiates a series of chemical reactions within our bodies which lead to the production of vitamin D (specifically, the body manufactures vitamin D3, or cholecalciferol – the most biologically active form).

For those of us who live in Canada, (or in other northern latitudes), late spring and summer are typically the times when sunlight is strong enough to be a major source of vitamin D.  Most sources claim that 10 to 15 minutes of sun exposure, to at least 40% of the body (without sunscreen), 3 times per week, is enough to produce the body’s requirement for vitamin D.

When exposing yourself to sunlight, always exercise common sense.  Be careful with your exposure and do not overindulge.  It is extremely important that you do not get a sunburn as this can increase the risk of certain skin cancers.  Build up your tolerance gradually, starting with just a few minutes a day.  Start in the spring and early summer, avoiding the peak sunburn hours (approximately 11:00am to 3:00pm, depending on where you live).  Frequent, short periods of regular sun exposure are best – and remember that you need to expose large portions of your skin – not just your hands and face.  If you use tanning beds, look for ones that have electronic ballasts to avoid harmful radiation and electromagnetic frequencies emitted by the commonly used magnetic ballasts.

Note that there are certain factors which can negatively affect our ability to make vitamin D from sunlight.  These include having most of our body covered by clothing when outdoors, using sunscreens with an SPF of 8 or more, skin pigmentation (a person with dark skin will need more exposure compared with a person with pale skin), pollution, cholesterol-lowering statin drugs, certain health conditions and aging.

While vitamin D can be stored by the body, most of us do not produce enough of it during the sunshine months to last us through the long Canadian winter.  In fact, our vitamin D levels can drop by up to 50% in the winter.  It is interesting to note that one hypothesis that is being put forward to explain the seasonal nature of the flu is that it is due to vitamin D deficiency.

Some sources claim that in North America, up to 90% of seniors and up to 70% of the general population have a vitamin D deficiency.  This high level of deficiency is very concerning given the number of important functions vitamin D has in the body, including fighting infections and strengthening the immune system.  In addition to being linked to the flu, vitamin D deficiencies have also been directly linked to multiple sclerosis, osteoporosis, Parkinson’s Disease, type 2 diabetes, depression/Seasonal Affective Disorder (SAD) and 22 forms of cancer.  Studies have also shown that individuals who regularly supplement with vitamin D have a lower risk of heart disease.  The results from a ten-year study involving over 18,000 men, age 40 to 75 and initially free from cardiovascular disease, discovered that “when all risk factors were considered, having low levels of vitamin D increases the risk of heart attack just as much as high blood pressure or smoking does”. (Archives of Internal Medicine  08:168:1174-1180). 

So, as we approach that time of year when soaking up enough sun in our shorts and tank tops or bathing suits is no longer possible (and not very enjoyable either!), it is clear that we should all be thinking about supplementing with vitamin D.  The question is, how much to take?

Most vitamin D supplements provide doses of 400 to 1,000 IU per day.    Health Canada recommends that the total daily vitamin D intake for the average adult, from both food and supplement sources, should not exceed the Tolerable Upper Intake Level of 2,000 IU (International Units), while many other sources state that 4,000 IU per day is safe (some sources claim even more is safe).

It is interesting to note that full-body exposure (with minimal clothing and no sunscreen) of pale skin to summer-time sunshine for 30 minutes can result in the synthesis of up to 20,000 IU of vitamin D.  While the body has a self-regulating mechanism to prevent too much vitamin D from being synthesized by exposure to sunlight, thereby preventing the possibility of toxicity, this is not the case with the vitamin D it gets via supplements.

It is possible to take too much vitamin D when using supplements; however, documented cases of toxicity typically involve mega doses that are far beyond the common 2,000 to 4,000 IU daily recommendations.  As toxicity is possible, it is recommended that you regularly monitor your vitamin D levels.  The only blood test that can do this is a 25-hydroxyvitamin D test, also called a 25(OH)D test.  Blood levels should be in the range of 50-80ng/mL or 125-200nM/L year round.

Note that vitamin D supplements are available in two forms:  vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol).  Recall that vitamin D3 is the form that the body naturally produces when exposed to sunlight.  Vitamin D2 supplements are a synthetic form and are typically made from commercially irradiated fungus/yeast, thereby providing a vegetarian source of vitamin D.  Studies reveal that vitamin D3 supplements are superior to D2 supplements.  Vitamin D3 has a stronger biological action compared with vitamin D2, being converted to a more active form 5 times faster than vitamin D2.

While it is unlikely that you will get your daily requirement of vitamin D from food alone, it is still worthwhile to make note of good food sources, which include:

  • sardines and fatty fish (e.g. herring, blue fin tuna, salmon, rainbow trout)
  • cod liver oil
  • organic organ meats
  • organic, free range eggs (vitamin D is found in the yolk – and I have heard that duck eggs have about 6 times as much vitamin D compared with chicken eggs)
  • dairy products fortified with vitamin D3 (e.g. milk, yogurt, butter and cheese – organic is best)

As vitamin D is a fat soluble vitamin, individuals with low dietary fat intake or compromised fat absorption due to specific health conditions or medications may have trouble with the absorption of vitamin D from foods and most supplements.  I personally take and recommend Bio-D-Mulsion 1,000 – a unique, liquid vitamin D supplement that has been micro-emulsified for greater uptake and utilization by the body.  This is beneficial for all of us, but particularly so for anyone with digestive/absorption problems, especially those that affect the small intestine (where the absorption of dietary vitamin D occurs).  The liquid format of this supplement makes it very easy for anyone to take.  One drop of Bio-D-Mulsion 1,000 supplies 1,000 IU of vitamin D3.  For more information on this product, visit

While fairly uncommon, there are certain conditions that require caution when considering supplementation, so it is wise to consult your health care provider before making a decision to add a new supplement to your diet.

If you would like to learn more about vitamin D, an excellent source of information and up-to-date research is the Vitamin D Council (

I look forward to continuing to partner for a healthier, more vibrant you!


From Seafood to Sunshine:  A New Understanding of Vitamin D Safety, Chris Masterjohn, Wise Traditions, Fall 2006

Over a Million People Die EVERY Year From Lack of Sun Exposure, Dr. Mercola, Special Report, Spring 2008

Vitamin D for Winter Health, Alternatives, Volume 12, No. 16, October 2008

Are you getting enough vitamin D?  Ottawa Citizen, January 20, 2008, B4-5

The Vitamin D Council (


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