Vitamin D and Living Above The 37th Parallel

It’s COLD!

For those of you reading from warmer climates, perhaps this post will make you feel even BETTER about having the sense to set up shop somewhere hot.  For the rest of us living in places that require a winter jacket, at least we have an excuse to drink hot chocolate and sit by a warm fire.  Two days ago, I had to get off my bike and get on the subway because it was so cold.  That was a signal that maybe riding in below 0 degree weather is a dumb move, but also it’s time to get in the habit of taking my Vitamin D supplement.

So, here is how Vitamin D works.  We have a cholesterol like substance called 7-dehydrocholesterol in our skin and once this substance comes into contact with sunlight it is converted into cholecalciferol.  The cholecalciferol moves to the liver and then kidney’s where it goes through two more conversion and eventually ends up as 125-dihydroxycholecalciferol or what we consider to be Vitamin D.

The original substance in our skin can never start the process of becoming Vitamin D without sunlight and if you live above the 37th parallel you’re likely lacking the rays required especially between the months of September to April.  Draw a line from San Fransisco to Philly, and Athens to Beijing –  anything north of this is above the 37th parallel.

You might be wondering, “why do I need Vitamin D in the first place“?  The primary use of Vit D is that it’s used in the gut to help absorb calcium and also works hard at maintaining adequate levels of phosphorus – both are needed for healthy teeth and bones.  It actually functions like a hormone in our body, works in close conjunction with parathyroid hormone and is structurally is very close to both estrogen and cortisone.

There is a strong correlation between colder climates and those with low levels of Vitamin D and the development of Multiple Sclerosis.  Furthermore, there is a belief that low levels of Vitamin D slow down our immune response – is it a coincidence that most colds and flu’s come on in the winter when our exposure to sunlight is at its lowest?  Finally, Vitamin D is involved in muscle and heart support, the prevention of certain types of cancer (ovarian, prostate, colon, bladder, rectal), and mood/cognitive support in the older population.

Food sources of Vitamin D include: salmon, sardines, fortified milk, eggs, and shiitake mushrooms.

Since it’s sometimes (often) hard to get enough Vitamin D from food, Health Canada and most natural health practitioners suggest that Canadians supplement as follows:

Age group Recommended Dietary Allowance (RDA) per day Tolerable Upper Intake Level (UL) per day
Infants 0-6 months 400 IU  (10 mcg) * 1000 IU (25 mcg)
Infants 7-12 months 400 IU  (10 mcg) * 1500 IU (38 mcg)
Children 1-3 years 600 IU (15 mcg) 2500 IU (63 mcg)
Children 4-8 years 600 IU (15 mcg) 3000 IU (75 mcg)
Children and Adults                      9-70 years 600 IU (15 mcg) 4000 IU (100 mcg)
Adults > 70 years 800 IU (20 mcg) 4000 IU (100 mcg)
Pregnancy & Lactation 600 IU (15 mcg) 4000 IU (100 mcg)

A note on “Upper Limits” – this means, just don’t take more that the amount indicated in the right hand column without consulting with a healthcare practitioner.

If you are breastfeeding or pregnant, the Canadian Pediatric Society has a comprehensive position statement on Vitamin D supplementation here, but it’s long so to summarize:  if you are pregnant and or nursing, supplementing at 4000 IU is thought to be beneficial for both you and your in utero and/or nursing baby.  Please check with your health care provider if you have any concerns about how much Vitamin D you should be taking.

Other special populations who might need to pay extra attention to Vitamin D supplementation include those who have issues with fat digestion and absorption (those who have had their gallbladder removed, Crohn’s Disease, partial stomach or pancreas removal) since Vitamin D is a fat soluble – it needs fat to be absorbed.

THE DAILY DL (Dalai Lama):

“Judge your success by what you had to give up in order to get it.” 

– Dalai Lama XIV


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2 thoughts on “Vitamin D and Living Above The 37th Parallel

  1. Pingback: The Health Junction’s 100th Post: A Year in Review « THE HEALTH JUNCTION

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