Vitamin D, you sneaky little devil!!

Are you wondering what the heck that picture shows?  It's supposed to look like the inside of your head (the squigglies are your brain matter, the chevron-ish symbol highlighted  with pink is your hypothalamus which sits just above your pituitary gland which is the highlighted asterisk... and then down below in the neck area is the thyroid gland which looks like a bowtie).

The picture is showing you how these different endocrine (hormonal) glands work together.  Well... the picture in addition to my notes scribbled to the side.  Let's talk a little bit about why you might want to up the amount of Vitamin D in your diet or add a sweet Vitamin D3 supplement.  Vitamin D has a lot of responsibilities, but this shows you just one of them.  Leptin signals the brain that we need more energy.  It sends a message to the hypothalamus.  The hypothalamus responds by sending TRH (thyrotropin releasing hormone).  Interestingly "thyrotropin" is another name for TSH (thyroid stimulating hormone).  TRH travels to the pituitary gland where it [the pituitary] responds to the influx of TRH by releasing TSH.  TSH does just like it sounds... it heads over to the thyroid gland, and stimulates it to release more thyroid hormones.  The thyroid gland creates/releases the thyroid hormones T4 (thyroxine) and T3 (triiodothyronine).  It releases a whole lot more T4 in comparison to T3.  In the peripheral (outer) tissues, the body can then convert free T4 hormones to the more active free T3 hormones as needed (free=not bound to protein, thus available for use).  In our cells, T3 aids in helping to create ATP (energy) within the mitochondria.  Mitochondria are our energy powerhouses.  This increase in the production of ATP increases our ability to perform more activity.  Thus energy is produced.

The ATP is generated in a number of different ways from the macronutrients (fat, carbohydrate and protein) we consume with a lot of complex cycles that aren't necessary for you to fully comprehend to appreciate how amazing they are.  We can create energy from the food you just recently ate, and also from food you ate a while ago that was stored for later use (as fat).  But what does Vitamin D have to do with any of this?  Well, in order for the Pituitary Gland to take the signal coming from the release of TRH and transform that into a release of TSH, it needs Vitamin D.

Vitamin D is in a difficult spot because unlike other vitamins, it can be manufactured by the body.  It leads some to refer to it as a pro-hormone.  Proper exposure of the skin to sunlight should be sufficient in producing enough Vitamin D.  But is it really?  We have long been told that those United States residents who live at or below the 35th parallel (no farther north than Amarillo, Texas - as a reference point) receive enough sunlight to not need Vitamin D supplementation, whereas those residing north of this area would need a supplement between the months of November and May each year.  

Sufficient levels of Vitamin D can be determined with a simple blood test.  Naturally all labs will vary some in their testing of this and what their "normal" range is.  I recently had mine checked just to take it off the list of possible issues in my personal healthcare journey.  Normal range for my lab was 30.0-100.0 ng/mL.  My Vitamin D level was 30.1 ng/mL!  I was shocked.  We have enjoyed a spectacular summer in the Pacific Northwest, and I spent nearly every waking moment outside enjoying it - with the worst track record for applying sunscreen to myself.  Surely this should have resulted in a fabulous Vitamin D level in the middle of the normal range (therapeutic range), not at the bitter bottom!

With these results, I then pulled out my combination Calcium, Vitamin D3, Magnesium and Zinc supplement to see what levels that would provide.  I was quite sporadic when I did take it (between November and May), and was disappointed to find that even when I took it, the tablets were only giving me about 400 IU's of Vitamin D - and the current recommendations are more like 2000-4000.  Apparently I wasn't alone.  Residents in Orange County California showed similar issues with their Vitamin D levels.  In a random sample of 151 residents, 19.2% were deficient in Vitamin D.  It was disappointing to see this, since they sit around the 33rd-34th parallel, and thus shouldn't need supplementation at all during the year.  The results of my own labs and those found in other parts of the country made me wonder how low my levels were dropping during the fall-spring months when our sunlight is so limited.  No wonder I would often feel so lacking in energy and motivation.  I had always attributed it to the short days and long nights... and the gloomy gray weather, but was lack of Vitamin D to blame too?

Vitamin D can take some time to show improvement in your baseline levels, though supplementation may make you feel better long before your labs reflect it.  Having your levels checked isn't necessary.  You can pretty much assume that you aren't getting enough if you spend very little time outside, wear tons of sunscreen, and live in an area of the country about the 35th parallel (which applies to most of us).  

Another way you may be able to assume a low Vitamin D level might be if your thyroid tests are sub-par.  This actually was the initial factor that has gotten me this far.  My energy level was very low and my body was beyond stubborn when it came to weight loss.  My TSH levels always came back within the normal range (TSH fluctuates during the course of the day), but my thyroid hormones were off.  My free T4 was below the normal range, and my free T3 was barely into the normal range.  We determined that my T4 was doing a fine job of converting to T3, but why was my body opting to produce so little of them?  It wasn't even being stimulated to make more - otherwise we would have seen an increase in TSH to help bring them up into the middle of the normal range where they might actually show some real benefit.  Could it be that my low levels of Vitamin D were preventing the signal from getting to the pituitary gland?  Or preventing the pituitary gland from doing something with the signal?  Time will tell.  I have started my daily dose of 2000 IU's of Vitamin D3 (yes choose D3 over D2) and in another 10 weeks (12 weeks from when I started) I get to have my Vitamin D level rechecked, in addition to a recheck of my free T4 and free T3.

If you're struggling with low thyroid levels and you live in any part of the country, you may want to seek out a high quality Vitamin D3 supplement to help encourage smoother signals in the brain to assist in creating more energy for your body.  The fact that you supplement D3 and raise your levels doesn't mean your body will lose weight as a result, but it may give your body the energy it needs to move more, and more exercise/activity could result in better body composition in the end.

1.  D'Emden MC, Wark JD. 1,25-Dihydroxyvitamin D3 enhances thyrotropin releasing hormone induced thyrotropin secretion in normal pituitary cells. Endocrin. 1987;121(3):1192-4
2.  Vidali S, Kneuver J, Lerchner J, Giesen M, Biro T, Klinger M, Kofler B, Funk W, Poeggeler B, Paus R. Hypothalamic-pituitary-thyroid axis hormones stimulate mitochondrial function and biogenesis in human hair follicles. J Invest Dermatol. 2014;134(1):33-42.
3.  Horani M, Dror A, Holland D, Caporaso F, Sumida KD, Frisch F. Prevalence of Vitamin D Deficiency in Orange County Residents. J Comm Health. 2011;36(5):760-764.