winter sun landscape

Do You Need Vitamin D This Winter?

Vitamin D is an important nutrient that we need for a strong immune system, gut and bones, but as the days get shorter there is less opportunity for Vitamin D synthesis in our skin via sun exposure. As winter approaches, make sure your body has adequate levels and take a supplement if needed. Work with your provider before adding a supplement if you are taking multiple medications or have multiple health conditions.

Disclaimer- This post is not intended to replace medical advice, merely to provide education about Vitamin D and it’s use.

Vitamin D is Essential

Vitamin D is essential for:

  • Maintaining a strong immune system 
  • Preventing leaky gut / intestinal permeability
  • Absorbing & transporting calcium into our bones and keeping it there (along with Vit K2)
  • Hormone synthesis

But did you know that 50% of the population has Vitamin D insufficiency? 

Sources of Vitamin D

   salmon and mushrooms

Vitamin D is created in our skin when it is exposed to the sun. 

In order to create enough of it to prevent deficiency, we must be in the sun for about 20 minutes with 40% of our skin exposed (varies by person). For those of us that live in the northern latitudes, this just isn’t going to happen from about May- October.

We’ve already had 15 inches of snow here in Wyoming by late October!

Vitamin D can also be acquired through some foods such as oily fish (salmon, herring, and mackerel), mushrooms, and egg yolks. 

Getting Vitamin D Isn’t Easy

Several factors slow our ability to synthesize this essential vitamin:

  • With the time change coming up, it becomes even more difficult to get outside while the sun is still shining. And for most people, getting outside during the shorter, colder days just isn’t as appealing. Because of this reduced sun exposure, most people just don’t make as much Vitamin D in the winter as they do in the summer. 
  • As we age our ability to make Vitamin D declines. 
  • Darker skinned people naturally create less. 
  • Sunscreen and moisturizers containing sunscreen greatly diminish our ability to create it, not to mention exposing us to toxic chemicals! I’ll post about that on another day (wink).


winter twilight

You can check you level using a serum Vitamin D test. Here in Wyoming, it is easy to do via the Wyoming Health Fairs. 

It is important to have an adequate level of Vitamin D, but also important that your level is not too high. If you have sarcoid, tuberculosis, hyperparathyroidism, lymphoma, or kidney disease check with your doctor before taking Vitamin D. 

It is recommended that you re-check your levels again 2 to 3 months after starting a supplement to make sure the dosage is adequate and that your levels are within normal range. 

Once in our bodies, Vitamin D must be converted into its active form with some help from magnesium. Since magnesium deficiency is very common in our society, I would recommend that you also have your RBC (red blood cell) magnesium levels checked when you get your Vitamin D checked. Depending on your level, you may want to add this supplement as well. 

Supplementing Vitamin D

If you have decided to start taking a vitamin D supplement, the recommended type is Vitamin D3 (cholecalciferol). The starting dose typically ranges from 1,000 IU to 2,000 IU taken once daily. This can vary by person so if you are on medications or have medical conditions or concerns be sure to check with your doctor or pharmacist before adding a supplement. 


This Sunday as you change back the clocks and check your smoke alarm batteries, remember to get your Vitamin D levels checked and consider adding a supplement to you routine if needed. And remember to #getoutside this fall and winter because we need that sunshine for making Vitamin D!

Work with your provider before adding a supplement if you are taking multiple medications or have multiple health conditions. 

Coming Soon:

As a functional medicine pharmacist, I will be providing one-on-one health coaching to optimize your health! Keep an eye on the blog for more information. 

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