Since my cousin’s breast cancer diagnosis before Christmas I’ve been learning more about Vitamin D. I was aware that Vitamin D worked in tandem with minerals like calcium and magnesium as well as influencing our immune system, insulin secretion, bone formation and blood pressure regulation but I had no idea that recent research has shown that we have Vitamin D receptors in nearly every part of our body and as yet don’t know the importance these receptors play in health and disease. In addition, research has shown a correlation between low Vitamin D and more severe breast cancers and high Vitamin D and increased survival rates, so our Vitamin D status is clearly hugely important yet doctors pay scant attention to it.
So what exactly is Vitamin D? It’s not one substance but a group of fat-soluble compounds that serve as pre-hormones to the active form of vitamin D which is called calcitriol. Within the group of compounds is vitamin D3, found in supplements, fish, egg yolks, and cheese and vitamin D2 which is synthesized by plants and is the form most often used to fortify foods such as milk. We also make vitamin D in our skin when we get out in the sun and our skin is exposed to ultraviolet-B radiation (UVB). This initial form of vitamin D, called 7-dehydrocholesterol, then travels to the liver where it is converted into another slightly more active form of vitamin D called 25-hydroxyvitamin D. It is this form of Vitamin D produced by the liver that doctors are testing when looking for deficiency. When vitamin D leaves the liver it travels to the kidneys where it is converted into the active form of vitamin D called calcitriol. This is no longer considered a vitamin but a steroid hormone. So Vitamin D is a highly complex substance embarking on a long journey which has the potential to go wrong at any stage.
Doctors can’t agree on how much Vitamin D is optimal for health and figures vary from 50-80ng/mL. Figures on what constitutes low Vitamin D also differ, from under 25 to under 11ng/mL.
Although we get some of our Vitamin D from foods most comes from the sun. In fact, recommendations from The Powers That Be say that we should get all the Vitamin D we need by exposing 30% of our unprotected skin to the sun for 5-30 minutes between 10am-3pm three times a week (though they don’t differentiate between the sun in Africa and the sun in Iceland!). However, from the response to my previous post we know this is rubbish and that many of us could live naked in the Sahara and still have low Vitamin D.
When we have routine blood tests done and our Vitamin D comes back below normal we are simply prescribed supplements and sent on our merry way. Not a single doctor asks why we are deficient, a situation I find mind blowing.
Doctors in the UK could be forgiven for assuming we’re just not spending enough time in the sun, especially in the winter, but the same can’t be said of people living in California or Perth yet they appear just as likely to be Vitamin D deficient as anyone else. The obvious conclusion is that people in sunny countries wear more sunscreen which is blocking vitamin D absorption but research on this subject has shown conflicting results. I personally hardly ever use sunscreen (I simply forget to put it on) and spend plenty of time outdoors both summer and winter yet my Vitamin D has been below 20 for at least the past five years.
We could assume we aren’t absorbing Vitamin D properly but where is the proof of this, and even it is the case why are we not absorbing? What’s going on? The answer: Vitamin D is such a complex substance the reason for low levels could be down to any number of things or even problems about which we are currently unaware.
We can’t look at any one blood result in isolation. Other substances like Vitamin K, Boron, Vitamin A, Zinc and of course Calcium affect Vitamin D, though my bloods show that for me these are all well within normal ranges. Magnesium also helps Vitamin D to work, so if you’re low in magnesium you’re not going to be utilizing Vitamin D properly. However, my recent blood test shows that I have too much magnesium in my system yet my Vitamin D is still low, which muddies the already unclear waters.
Lots of us with low levels of Vitamin D in our blood take supplements despite not knowing the reason for our deficiency (which might be nothing to do with needing more Vitamin D), but even the information on supplementation is hugely confusing. In particular the level we should be taking can’t be agreed upon and my cousin with breast cancer was already on a supplement yet still had virtually no Vitamin D in her blood! In addition little is discussed about the perils of supplementing. For example, taking high doses of Vitamin D can affect Calcium levels, too much of which can cause kidney stones and calcification of the arteries increasing our risk of cardiovascular disease.
The more I’ve read about Vitamin D the more confused I’ve become and the more I’ve realized how complex this one little Vitamin is and how little we actually know about its role within the body. One study says sunscreen is to blame for deficiency while another says it has no impact. One study says we should supplement while another says unless we know the reason for low blood levels we absolutely shouldn’t. It leaves my head spinning.
Once again I would never have known my Vitamin D levels were below normal had I not requested a print out of my blood results. My GP has never mentioned it or suggested I need a supplement, which is hugely disappointing, and I have absolutely no idea why my levels are low. Off my own bat, and not knowing whether it’s the right thing to do or not, I have been taking a supplement in the form of a liquid drink (my mast cells as you know dislike tablets), but I won’t know how effective this has been until April because the lab won’t re-test Vitamin D levels within one year of the previous test. I only hope I’ve not buggered up some other vital mineral in the process, or made my already high magnesium levels even higher.