How Much Vitamin D is Best?

I know I need vitamin D, but how much should I take?

This is a question I hear often, so today I thought I would share my own experience with vitamin D and provide a reminder of how important this vitamin is to health, especially in the winter!

What is vitamin D?

Humans primarily make vitamin D via our skin from exposure to ultraviolet light.  Actually, we make cholecalciferol which is converted into fully active vitamin D by our liver and kidney cells.  Vitamin D influences the following major areas of healthy function:

  • Bone health
  • Blood sugar control
  • Immune support

Beyond these major areas, there are many therapeutic uses of vitamin D supplementation and more emerging every day as research on vitamin D evolves.  In my practice, I consider vitamin D for many types of female hormone imbalance, elevated cholesterol, and long-term health promotion.

Most adults are deficient in vitamin D and can benefit from increasing their vitamin D.  According to Health Canada, only 1/3 of the population has vitamin D levels above 75 nmol/L, which is the lower level for “sufficiency.”

Why are we deficient?

1. We don’t get naked enough!

Imagine how early humans lived…  They wore little clothing and spent most of their time outdoors in warm weather, so they made lots of vitamin D in the summer, which was stored in their bodies and used during the darker winter months.

Is this how you live today?  I doubt it!  Most of us spend most if not all our time indoors and when we are outdoors we cover up with clothing, hats, and sunscreen.  All of this means we make little to no vitamin D at all from the sun.

2. We can’t eat enough vitamin D!

Unlike most other nutrients, there are few foods that provide vitamin D.  Because we mostly get vitamin D via the sun, food is really just a back-up support system in this case.

The World’s Healthiest Foods website only lists 6 foods as sources of vitamin D:

  • Salmon
  • Sardines
  • Tuna
  • Cow’s milk
  • Eggs
  • Shiitake mushrooms

3. Other circumstances

There are several other factors that impact vitamin D levels:

  • Season
  • Latitude
  • Age
  • Medications
  • Skin pigmentation

The test is best

The only way to know for sure whether your vitamin D level is normal and how much you may need to supplement is to test your vitamin D blood levels.

My results: then and now

September 2009

The first time I ever tested my vitamin D level was in September 2009.  At that time, I was already supplementing with 2000IU vitamin D3 daily.  I was not a big “sun-worshipper” but I tried to get outside regularly to run and never wore sunscreen unless I was going to be out in the sun for more than an hour.  As you can see, at that time, my vitamin D level was 77 nmol/L, just at the low end of “sufficiency”:

KW vit D Sep 2009

February 2010

After my test in September, I increased my supplementation to 4000IU vitamin D3 daily over the winter and retested in February 2010:

KW vit D Feb 2010

As you can see, my vitamin D level increased in that 5 months to 87 from the increased supplementation.  Yay!

November 2014

I recently decided to test my vitamin D again.  This time I used a different test that involves doing a finger prick in-office to collect a blood sample on a collection card and sending it in the mail for analysis.  Once again, my regular supplementation level was 2000IU vitamin D3 daily, and once again I was “mildly” deficient in vitamin D:

Kate VitaminD

So, once again I’m going to increase my supplementation to 4000IU vitamin D3 daily and I should probably continue this dose or slightly lower to keep my levels in the optimal range.

4 Responses to How Much Vitamin D is Best?

  1. Luana December 27, 2015 at 6:52 pm #

    Ok I am only taking 2000 units per day so I probably need to be retested.

    • Dr. Kate Whimster, ND December 31, 2015 at 6:55 pm #

      Definitely a good idea to test your levels to determine the right supplementation for you!

  2. Tom Martens April 22, 2016 at 10:01 am #

    Did you feel any different or notice any differences with the “low” level and the “normal” level?

    • Dr. Kate Whimster, ND April 25, 2016 at 2:42 pm #

      Hi Tom,
      No, I did not feel different at different levels, and that is the problem with vitamin D – you need to test to understand where you are at and how to supplement appropriately! The “symptoms” of vitamin D deficiency are really related to outcomes of chronic deficiency, such as osteopenia/osteoporosis, etc.
      Hope that helps!

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