Vitamin D- Are you getting enough?

Ever notice how so few kids have runny noses in the summer compared to winter?  Most of us can also feel a distinct difference in our mood and in those around us when the sun finally comes out after a long gray winter.  There is something to be said about the sunshine.   A few weeks ago I attended a Vitamin D Symposium at Dalhousie University.   It was very informative and I’ve been telling my patients all about it and its importance ever since the seminar.  Everything from bone health, stronger immunity, mood elevation, different cancers, diabetes, headaches, achy body, MS, etc… has been shown to be linked to vitamin D levels in our body.  Vitamin D is an essential nutrient, are you getting enough?

What is it?  Considered to be “the sunshine vitamin” since it can be synthesized in the body with adequate exposure to sunlight.  It is required for proper functioning of the repair mechanism in the cell.  It acts as the key that unlocks the DNA library.  Without this essential nutrient, chaos can result in the cell as it tries to reproduce itself to make the body thrive in its environment.

Where do I get vitamin D?  Sunshine is the most natural source of vitamin D, mainly the UVB exposure.  There are many factors that influence how much vitamin D is produced in response to UVB exposure.  The most well-known factor is the angle of the sun’s rays.

Time of day, season, and latitude all determine the amount of UVB that reaches your skin. When the sun’s rays enter the Earth’s atmosphere at too much of an angle, the atmosphere diffuses (blocks) the UVB portion of the rays.  This occurs during the early and latter parts of the day, during the winter season (what is called “Vitamin D Winter”), and increases as one moves further away from the equator. A good rule of thumb is: If your shadow is longer than you are tall (an indicator of the oblique angle of the Sun), you are not making much vitamin D.

Time of day:  For vitamin D production, sun exposure should be midday between the hours of approximately 10am-2pm. These hours will vary slightly according to latitude. The closer to solar noon, the more vitamin D produced.

Season- Vitamin D Winter and latitude:  What latitude you reside at will affect the length of your Vitamin D Winter. Vitamin D Winter is when no vitamin D production is possible due to the atmosphere blocking all UVB. This lasts for several months, with the duration of time increasing as you move further from the equator. For many of us living in the Northern US and Canada, our Vitamin D winter can be as long as from the end of September to May.  Many people tell me they are outside a lot in the winter and get adequate vitamin D from that exposure.  Unfortunately, even if we (at our latitude) were fully exposed all winter, we would get minimal if any vitamin D from the sun during that vitamin D winter season.

How long should I be outside?  In an optimal environment (middle of the day in the summer) a light skinned person wearing a bathing suit will make about 15,000IU’s of vitamin D in 15-20 minutes.  Darker skinned individuals can do the same, but it will take twice as long.  The body will stop its production of vitamin D through a feedback loop after about 15,000IU’s.

What is the effect of sunscreen?  Sunscreen blocks UVB and prevents the manufacture of Vitamin D.  We have been warned so much about the dangers of skin cancer that we often forget that over the last century we have been steadily decreasing the amount of time we are spending outdoors.  Fewer and fewer people are working outdoors, more people are working in offices.  More individuals have been wearing sunscreen than any other time in history.  Yet, the rates of skin cancer are steadily increasing.  One of the things we definitely want to avoid is getting a  sunburn.  When we go south in the winter with the kids, after having been away from strong sunlight for so long, we are usually very pale.  We bring a natural sunscreen with us (with ingredients we can pronounce) from Burt’s Bees, Aubrey Organics etc…  We allow ourselves to go out for 10 minutes or so until we feel the skin get a little warm.  We then apply a natural sunscreen or apply more clothing so we can avoid burning in the first few days.  Over the week, our body gradually acclimatizes to the new environment. We can then make sure we are getting adequate exposure to provide our body with the ability to naturally produce vitamin D.

“For hundreds of thousands of years, man has lived with the sun: Our ancestors were outdoors far more often than indoors. We developed a dependence on sunshine for health and life, so the idea that sunlight is dangerous does not make sense. How could we have evolved and survived as a species, if we were that vulnerable to something humans have been constantly exposed to for their entire existence?” ~ Dr. Frank Lipman, internationally recognized expert in the fields of Integrative and Functional Medicine and practicing physician.

Does the body have to process vitamin D before it becomes active?  The body converts vitamin D, whether by mouth or made in the skin, to a compund called 25-hydroxyvitamin D 25(OH)D.  This compound circulates in the blood and is the measure physicians or scientists use to assess vitamin D status.  High levels of serum 25(OH)D show that you are getting enough vitamin D, while low levels indicate deficiency.

How much vitamin D do I need?  One of the only ways to determine for sure if you have adequate levels of vitamin D is from a blood test.  You can request one from your medical doctor or naturopath.  Once you get your results, ask them for the exact number because you want to be somewhere between 100-150nmol/L (40-60ng/ml in the US).  The following chart will show you that for the purpose of avoiding rickets (bone deformities caused by lack of vitamin D) you want to be above 50nmol/L (20ng/ml).  If your levels are 130 and above, you can decrease your chance of breast cancer by 83%.  It is important to take what is necessary to not only keep you above the rickets zone but in the cancer and disease fighting zone.  That is where I choose to be and it has taken me a dosage of about 12,000IU’s/day this winter to get at 153nmol/L.  I am not recommending you take this much but if you are deficient (in Canada, 97.7% of individuals are below 125nmol/L and 90% are below 100nmol/L), it is important to adjust your levels accordingly.  That is a lot of people who are deficient by these standards.  When you do start supplementing, your levels may spike more at the beginning and then slowly over the next few months.  It can take from 3-6 months to get your levels back up to the desired range.  If you don’t have the opportunity to get tested any time soon, you can take about 5,000IU/day as recommended by the vitamin D Council.  That is a good place to start.

How much do I need to take during pregnancy?  There isn’t a more important time to be sufficient in this essential nutrient than during a period where your body is literally making another human.  Once again, it is ideal to achieve the same levels of sufficiency of 100-150nmol/L.  It may just require a little more to do so since the demands in your body are higher during pregnancy.  Taking vitamin D supplements during pregnancy is not only safe for mother and baby, but also can prevent preterm labor/births and infections.  If you’re not getting tested, take the recommended dosage by the vitamin D council of 5,000IU’s/day.

Is Vitamin D safe?  When consumed in reasonable quantities, it is not only safe but essential to the proper function of every cell in the body.  It is instructive to know that outdoor workers have levels of 150-200nmol/L (60-80ng/ml) by the end of summer.  If taken in abnormally high doses, vitamin D can produce severe toxicity in the body.  There have been no reported cases of toxicity below a dosage of 40,000IU’s/day or a blood serum level of 500nmol/L (200ng/ml) .

What about calcium and vitamin D?  Vitamin D enables the body’s regulation of calcium absorption.  Inadequate intake of calcium or vitamin D will lead to insufficient calcium absorption.  Be sufficient in vitamin D so you can absorb the calcium from your food.

Is it important to take vitamin D daily?  As long as the total dose is sufficient, vitamin D does not have to be taken every day.  Some doctors prescribe weekly or monthly dosing.  The important thing is to achieve and maintain a range of 100-150nmol/L (40-60ng/ml).  I usually tell my patients to take their top 3 essential nutrients (vitamin D, omega 3 fish oil, and probiotics) together on a daily basis so they will remember and make it a habit.


  • vitamin D is an essential nutrient for proper function of each and every cell in the body
  • the majority of the world population is now considered deficient
  • the best source is from sunlight during the peak hours of the day (10am-2pm), in Canada and Northern US from May-September
  • 15 minutes with as much of the body exposed as possible in a light skinned individual can produce up to 15,000IU’s.  For darker skinned individuals, it takes twice as long.
  • Studies are now showing evidence beyond skeletal health with increased immune function and decreases in some cancers, MS, etc…
  • If you are in a Northern climate or not getting outdoors for sufficient amounts of time to naturally produce vitamin D, then supplement to get your body sufficient (between 100-150nmol/L).  This dose may vary widely but a good place to start is 5,000IU’s/day according to the Vitamin D Council.  Get tested by your doctor or naturopath to determine what your exact levels are.
  • For kids, they should be within the same range as adults and since their bodies are smaller, they may require less.  One rule of thumb is 75 IU/kg of body weight/day.  For instance if your child weighs 20kg, an amount of 1500IU/day may be sufficient.

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