Friday, June 13, 2014

Vitamin D intake and All-Cause Mortality: a No-Brainer...


Having recently relocated to a more tropical locale, I got to thinking: is all the buzz about Vitamin D true? And, if so, what can I do to ensure that I obtain enough vitamin D daily?

A recent meta-analysis review paper (published in December 2013) provides decent background on the subject.  Having a certain range of Vitamin D levels in your blood lowers your chance of dying from any cause - it lowers your All-Cause-Mortality.  Here are some more specifics:

Adequate Vitamin D levels have been shown to slow cancer growth in cancers or the skin, colon, breast and prostate.

Being deficient in Vitamin D has been shown to influence the development of type one and type two Diabetes.

High Blood Pressure and Heart Disease:
Inadequate levels of Vitamin D have been linked to high blood pressure and development of atherosclerotic plaque.

Adequate levels of vitamin D are essential to proper bone health and preventing osteoporosis.
Vitamin D deficiency has been linked to infections and several auto-immune conditions such as multiple sclerosis.

In summary, inadequate Vitamin D levels have been regarded my many as a marker for premature death. 
The picture below shows this in graph form: (feel free to compliment my artistic abilities later)

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basically, on the x axis (bottom line)are vitamin D levels, on the y axis relative risk of all cause mortality. This U-shaped curve demonstrates that risk of dying is decreased with vitamin D levels of 27.5 ng/mL on.  Curiously though, the risk increases as vitamin D levels get too high. 

So, what is the magic number of vitamin D needed in the bloodstream? 
If you want to know your blood levels of vitamin D any friendly doctor can order the test to measure it for you.  Most experts agree that over 20ng/mL is enough - but newer research tells us that levels of over 30ng/mL are better.  In my expert opinion I think somewhere between 30 and 70ng/mL is best.

 How do I ensure that I am getting enough vitamin D daily?
Vitamin D's main source is us: we produce it in the skin after we are exposed to sunlight (UV-B radiation).  Ideally we would need to sit naked in the sunlight for about 20 minutes daily. But not all of us are able to sit in the sun for 20 minutes daily, let alone naked in the sun.  Or, we live at a latitude where it would be very difficult or impossible to obtain enough sunlight.  Also, as we age our ability to convert this sunlight to vitamin D diminishes (we become less efficient at it).  So for many of us sunlight may not be the only way we can get enough vitamin D.
What about diet?  Can we get enough vitamin D3 from eating plants and vegetables?  The truth is this is a difficult vitamin to get from plant based food sources - mushrooms exposed to ultraviolet light are the best option.  For the carniverous folks reading this salmon, mackerel and tuna are ok sources but it would still be difficult to obtain adequate levels.  Besides this, the next best thing would be to take a supplement.  I am usually not a person that recommends popping a pill - I don't even recommend a multivitamin.  But, Vitamin D in my opinion is so important we need to make sure we obtain enough of it.  As for me I will continue to plan on surfing, sailing and hiking to obtain adequate vitamin D levels with occasional supplementation to back this up.

Bonus question: Is there is a difference between Vitamin D2 and Vitamin D3?
The jury is out on this. There are two types of supplements available: vitamin D2 and D3.  Does it make a difference which one I take?  Recent studies have shown that vitamin D3 (mainly from sunlight, and certain supplements) has been linked to the lower all-cause-mortality.  So if you end up taking a supplement vitamin D3 is recommended.

So, in conclusion,
Adequate Vitamin D levels reduce all cause mortality.
Try to get it from sunlight.  If that is not possible, try some supplements.
It is a good idea to get your vitamin D level checked to get a good idea where you stand on this.

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Aloha - Peace, love and scalpels

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