Vitamin D: What You Need to Know

If you want to stay healthy through the winter and beyond, don’t forget your vitamin D!

Where I live in Portland, OR, we’ve had an abundance of sunshine-filled days this winter- a rare treat! But no matter the season we need to be attentive to how much vitamin D we get. I’ve talked about winter blues in a past blog post but the blues aren’t the only issue we face with shorter, darker days. We also face lack of vitamin D, aka, the “sunshine vitamin.”

This vitamin plays an important role in making your bones strong, helping your immune system to work properly, and it even controls the expression of over one-thousand genes in your body! It prevents bone loss, and studies even show it can help prevent cancer, diabetes and cardiovascular disease.

The most direct way to get the D you need is through sun exposure.

The body is incredible in that it can take the UVB radiation from the sun and convert it directly to usable vitamin D! But in most places the winter the sun does not come out enough for this to be possible. And, if you’re lucky enough to live in a sunny place, if you wear sunblock…no vitamin D. And it’s also important to know that the darker your skin the less vitamin D you absorb. In short, for many people, if not most, it’s difficult to get enough sun to get enough vitamin D.

There are food sources that have small amounts, including fatty fish, egg yolk, beef liver, cheese (if you eat dairy), and sun-exposed mushrooms. Unless you eat a lot of these foods though, it’s unlikely that you will be getting enough vitamin D.

This is where supplementation comes in. The best way to ensure you have adequate vitamin D levels is to take a vitamin D3 supplement. Vitamin D2 supplements are available, and most often prescribed by MDs, but vitamin D3 is most effective at raising blood levels. D3 supplements are typically derived from animals and D2 are plant-derived, although there are now vitamin D3 supplements derived from lichen, a vegan-friendly source!

Before you buy a D3 supplement it is important to first get your blood levels tested.

Testing will help you determine if you are deficient, within normal limits, or have too much vitamin D. For vitamin D, there is an ideal blood level which you should have tested with a trained physician or nutritionist who understands about the importance of vitamin D and the difference between D2 and D3.

  • Under 30 ng/mL = deficient
  • 30 ng/mL – 40 ng/mL adequate but not ieal
  • 40 ng/mL – 70 ng/mL ideal (for most people)
  • 70 ng/mL – 100 ng/mL = possibly too high
  • Over 100 ng/mL = top of acceptable range.

Vitamin D is a fat-soluble vitamin, which means it can build up in your system, so it is important not to overdo the supplementation. Generally, supplementing with 1000-4000 IUs per day is considered safe. I will often use higher doses with patients based on their individual needs.

Your practitioner should do follow up tests until you know that your your level is within the ideal range and that you are on the right amount to maintain it. This is truly the only way to be sure of the proper supplementation dose.

You need vitamin D for healthy bones!

There is another very important thing to consider with vitamin D—it has a direct effect on the amount of calcium you absorb from the foods that you eat. When you have a vitamin D deficiency, you may only absorb 10-15% of dietary calcium. With adequate levels, you absorb about 40% of your calcium. It’s a big difference! You need the that calcium for your bones, and you don’t want it milling about in your blood it can build up over time causing blockage of blood vessels increasing your risk of both stroke and heart attack.

A quick note on that calcium. In order to make sure it doesn’t build up in your vessels it’s best to take the right form of calcium (if you’re taking it)—I recommend calcium citrate, and enough K2 to activate the carrier proteins that shuttle calcium into your bones. You can get that in a supplement made from natto, a kind of fermented soybean. You can also eat it (natto) but it’s a bit of an acquired taste to say the least (as in…you couldn’t pay me to eat it.)

Now go get some sun on that pretty face!

Yours in Health,



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