In my first article about vitamin D, you learned all about what it is, how you get it and why it is so important for optimal health and performance, from a physical and cognitive standpoint. In this article, you will find out how most supplements and multivitamins do not provide enough vitamin D to keep most people within ideal ranges during winter, or when there is less chance for sun exposure, and what you can do about it.
First Test
As I mentioned in the first article, I tested my vitamin D serum level in May this year and found it was 46ng/ml. Now, if you remember, the level under which you are classified as deficient in vitamin D is 30ng/ml and that the research points to the sweet spot as between 40-60ng/ml for optimum bone health, immune and cognitive function as well as decreased cancer risk and DNA damage associated with accelerated ageing.
So, after 5 years of regular sun exposure in Rio de Janeiro, followed by a year of endless summer when we were in the UK followed by summer in New Zealand, my vitamin D level was in the low end of that sweet spot. With this level at the start of winter, I thought that without supplementation I would be well within deficient levels by the time spring and summer rolled around again. So I purchased some liquid vitamin D drops, for easier control over dosage, and have now spent the last 3 months of winter taking 5000IU a day based on an average of the recommendations per kg of bodyweight that I have seen.
I wanted to make sure I was getting enough but also not mega-dosing the stuff as that can lead to an excess of free calcium in the body, which can end up in arteries or heart tissue instead of bones and teeth where it should go. Many people have heard that having healthy levels of vitamin D leads to better absorption of calcium, but what most don’t know is that vitamin K2, an essential vitamin found in butter and other animal fats, is necessary for shuttling the free calcium to the right places in the body and avoiding calcification of arteries.
Now, just to let you know, 5000IU is over 12 times the RDA of 400IU as stated on most multivitamins. Dedicated vitamin D supplements usually state the dose as 1000IU daily. However, as we now know, skin colour, age, body fat levels, sunscreen and how much sun you get all influence how much you would need to supplement to stay in the vitamin D sweet spot.
Spring Re-test
So, having spent 3 months taking 5000IU of vitamin D per day (This is the one I take that has vitamin K2 as well), I got a repeat blood test done and was keen to see if I’d hit 60 or 80ng/ml, or even higher. It has been 3 months of not very much sun at all in Auckland at 36 degrees south of the equator, with lots of rainy days, but still some warmer days with sun on the face, arms and legs. So I thought my levels would be fairly high, maybe too high.
So, I was surprised to find out that my current level is only 44ng/ml. If you remember, thats actually lower than what I tested before the winter (46ng/ml). From this I can assume that if I was not taking any supplemental vitamin D at all through the winter, I would be well into deficient levels by now.
I have seen many people being ill with colds and flu and all sorts of viruses, yet neither my wife, our two kids or myself have had any illness to speak of. So maybe there is something to be said for the immune boosting benefits of healthy serum vitamin D levels.
Sun Specifics
As I mentioned in the previous article, there are only very low levels of vitamin D in food sources, so we must rely on sun exposure to get most of it. However, not all sun exposure is created equal. The latitude of where you are, the time of year and the time of day or, more specifically, the angle of the sun above the horizon, all influence how much vitamin D your body can synthesise from UVB on the skin.
It was previously thought that the sun had to be at least 50 degrees above the horizon to for UVB rays to penetrate the earth’s atmosphere. However, experts in the field now suggest that we can synthesise vitamin D from the sun when it is as low as 30 degrees above the horizon. Or, as a simple rule of thumb, when it is warm enough outdoors to expose large amounts of skin. This is probably why we hear the recommendation that those living above or below 37 degrees of latitude from the equator should supplement with vitamin D. Because, on a mid winters day at 37 degrees of latitude, the sun will peak at 30 degrees above the horizon.
There is an app called dminder which can estimate how much vitamin d you are receiving from the sun. It asks your current level if you know it, and calculates vitamin d synthesis based on where you are and how long you spend in the sun each day, taking into account how much skin is exposed and your skin pigmentation. It doesn't take into account sunscreen use though. Personally I find it too much of a hassle to hit the app's button every time I go outside and tell it how much clothing I’m using. But it is a great resource for estimating what time of day you can make vitamin d wherever you are, and the rate at which you make it. You can also input the amount you supplement to add to the total daily dose from the sun.
So to simplify all that information, get a good amount of sun exposure but don't get burnt. If you're interested, get tested for vitamin D levels, it's really simple, and you can be sure if you should supplement based on where you live and the time of year. Enjoy!
Any doubts, please ask questions in the comments section below and I will get back to you.
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