The sunshine vitamin: the many functions of Vitamin D
We here in the northeast US are heading, once again, towards the shorter days of autumn and winter. I, for one, dread the impending lack of daylight. There’s something about the seeming endless supply of sunshine during the summer months that makes me feel really, really good. My research tells me I’m not alone – exposure to sunshine boasts a few physiological benefits that we sometimes take for granted. One of those benefits has to do with the relationship of sun exposure to the body’s production of Vitamin D. So before winter hits, let’s explore the significance of Vitamin D and sunshine.
Some history on Vitamin D
It’s actually pretty amazing. Scientists have been researching Vitamin D, aka “the sunshine vitamin,” since the early 1900s when children of industrialized areas were developing Rickets, a disease of severe Vitamin D deficiency that leads to weak bones. Putting two and two together, it was quickly determined that those who lacked sun exposure also lacked Vitamin D, as Rickets was rare among those working outside in rural areas. Almost immediately, the fortification of foods and beverages with Vitamin D began and thus the “problem” of severe Vitamin D deficiency was all but eliminated. Or so we thought.
Over the subsequent years, there have been many “new” diseases that have popped up, many of them chronic. Further studies began to show a correlation between the increase of these diseases and decreased sun exposure. This isn’t surprising since a large percentage of our industrialized population spends the majority of time office-bound or when outside, lathered with sunscreen! But how could lack of sun have such a detrimental effect on the body’s functioning?
The sun and vitamin D
Vitamin D3 (Cholecalciferol) is made in the skin when exposed to UVB light (sunshine). During the summer in most geographical areas, it’s possible for the skin, when exposed, to produce between 10,000 and 50,000 IU’s of D3. Once it produces about 20,000 iu’s, the same UVB rays that make the D3 begin to degrade any D3 that is deemed unnecessary or “extra”. So the body has an internal regulating mechanism that protects us from Vitamin D toxicity when we are getting it from the sun.
The next step is what is most fascinating to me: after D3 is made in the skin or taken orally as a supplement, it is moved to the liver and becomes 25(OH)D (Calcidiol). This is the form of Vitamin D that is tested when you get a Vitamin D blood test. Maintaining a serum Calcidiol level above 40 ng/mL is key for optimal health (unless you have a hypersensitivity to Calcidiol, which is a very rare condition.)
Now, there are two routes that the Calcidiol must follow after moving on from the liver, but if your levels are lower than 40 ng/mL on your Vitamin D blood test, it is very likely that only the first route can be followed. That first route is to the kidneys where Calcitriol is made. Calcitriol is the form of Vitamin D that is absolutely necessary – it circulates in the blood and regulates blood calcium levels. That’s also where Rickets comes into play – when you don’t even have enough Calcitriol to regulate blood calcium, the necessary calcium will be pulled from the bones, making them brittle.
Okay, so say you have enough Calcitriol to regulate your blood calcium. That should be enough then, right? Well, that’s what scientists originally thought. But actually, the answer is “no.” This is the amazing part – once the kidneys have all of the calcidiol they need for serum calcium regulation, the “leftover” calcidiol moves on to the tissues and becomes Tissue Calcitriol. The more calcidiol there is, the more calcitriol is made. Picture water flowing into a big hole in the ground and then overflowing onto the surrounding landscape once that hole is filled. That’s, in essence, what happens to the Calcitriol. The only thing that limits the overproduction of calcitriol in the tissues is the body’s natural degrading of excess cholecalciferol, way back in the first part of the process. Tissue Calcitriol is the most potent steroid hormone in the body and is an amazing cancer/disease fighter due to its ability to turn genes on and off.
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I’ll summarize: Sunshine or supplements (cholecalciferol (D3) > Calcidiol (liver) > #1 Calcitriol (kidneys) for blood calcium regulation AND IF THERE ARE LEFTOVERS > #2 Calcitriol (tissues) for disease prevention and on/off switch for genes
It has been shown that, to increase blood levels of 25(OH)D (D3) to optimal levels you would need an additional intake of 1700 IU of Vitamin D3. If you merely shoot for the current RDA of 600-800 IU daily of D3 (depending on age) there would be no effective increase in D levels, thus depleting the “tank” and leaving virtually no Calcidiol to do its magic as Calcitriol in the tissues.
How to get enough Vitamin D3
Although some food products like milk are fortified with Vitamin D, it is difficult to get what you need from food so sun and supplementation are your best bets for maintaining an optimal D3 level.
If you live in the tropics or the southern states year round and get at least 20 minutes of mid-day sun exposure daily, you probably don’t need to supplement with D3. Keep in mind, however, that many factors affect how much Vitamin D your body will produce when exposed to the sun including skin type (dark-skinned folks tend to need more sun than fair-skinned individuals to produce the same amount of D3), time of day (more D3 is produced via mid-day sun), and amount of skin exposed. Check out the Vitamin D Council’s advice on how to get the D3 that your body needs.
If you find that you can’t get enough D3 through sun exposure, the Vitamin D Council recommends that adults supplement with 5000 iu’s of D3 daily, while children should stick to 1000 iu’s per day per 25 pounds of body weight. Children 1 year of age and younger should supplement with 1000 iu’s per day. After doing this for a couple of months, have your D3 blood levels checked to be certain that your 25(OH)D level is maintained between 50–80 ng/ml (125–200 nmol/L). Adjust supplementation accordingly.
Make sure you're getting the most out of your D3 supplement
One last very important fact about Vitamin D3: it works best with certain other nutrients called “co-factors”. So I recommend choosing a D3 supplement that also contains magnesium, boron, Vitamin K and zinc. I personally prefer “D3 Plus” by BioTech, which has all of the above cofactors included along with 5000 IUs of D3. You are welcome to purchase this through my online dispensary. (See below for the link and more information.) If you are already getting those cofactors from a quality multivitamin, be sure to choose a supplement that specifies the D3 form of Vitamin D (not D2, as it’s not well-absorbed). Contact me or visit my dispensary for more options.
I hope that I have done justice to the incredible health benefits that Vitamin D3 can provide. If your health needs go beyond the scope of a blog post, set up a complimentary 30-minute phone consultation and I’ll do what I can to help you.
May your days be filled with sunshine!
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