All About That Vitamin D

One of my hobbies is succulent gardening.  I live in California so it works with the weather, plus I’m lazy so needing borderline no maintenance is a huge plus.  As I was digging around in the soil, and muttering curses as I attempted to gracefully jam plants into the above pots, the sun popped out of the clouds and damn did that feel good.  So good it gave me some inspiration for my first official blog post, but first marvel at my new succulent terrariums.


So let’s get into the science of the D, Vitamin D that is 😉



What is Vitamin D?

Vitamin D is what our body produces when the sun hits our skin.  But we all knew that right?  What you might not have known is Vitamin D has two different forms (VD3, cholecalciferol and VD2, ergocalciferol).  As humans our body creates VD3 when our skin is exposed to sunlight(fish oils and egg yolks can give you a little bit too [Holick, 2011]).   Therefore, it is endogenously made, or created by your own body. #fancywordoftheday.  Specifically, when the sunlight hits your skin it converts cholesterol into VD3.

Fun fact: because your body manufactures VD3, some experts consider it more of a hormone than a vitamin.

I know what you’re thinking right now but before you strip naked and bake yourself in the sun, no, laying out in the sun is not going to convert all your cholesterol away.

Something else maybe you didn’t know: We get VD2 when we eat food. It is exogenously created, or produced outside of the body for our consumption. So what’s commonly referred to as “Vitamin D” has two separate forms, both of which are equally important!

Here’s the kicker, both VD2 & VD3 is completely useless.  Yup, up until they get transported to the liver and converted into 25-hydroxyvitamin D [25(OH)D], also known as calcidiol, they are “biologically inept.” Even after it changes into this new form, it’s inactive, so this form can’t do anything until it reaches your kidneys.  There it finally transforms into it’s active form 1,25-dihydroxyvitamin D [1,25(OH)2D], also known as calcitriol.

Whew!  I know, Vitamin D has quite the journey.  It has to journey from your skin/food you eat, to the liver, and finally the kidneys until it can even start to do it’s job.



So I Got the D, Now What?

Once active it does a few important things in your body.

  • It’s biggest role is how it influences Calcium and helps your bones and teeth.  It tells your gut how much of it to absorb.  Calcium is needed for bone growth and without it bones become brittle, misshapen, and thin.
  • Another interesting find is that adequate levels of Vitamin D may reduce your risk for Type 2 Diabetes.  There’s currently a large study being conducted to see how true this actually is.  The physiology: low levels of Vitamin D can have an adverse effect on the amount of circulating insulin.
  • Vitamin D is huge during pregnancy too.  Adequate levels are said to help prevent the child from developing Type I Diabetes.  It also helps prevent preeclampsia.  On the flip side though they say that too much Vitamin D during pregnancy can result in food allergies developing in the child [Benettia, 2015].

There’s a few more, but the big take home: make sure you have adequate amounts of vitamin D so your bones are strong enough to salsa their way into old age.


What happens if you DON’T have the D

Well that’s called Vitamin D Deficiency and it’s actually a major public health problem.  Who gets it:

  • Vampires or people who don’t get enough sun *COUGH* just about damn near everyone *END COUGH*
  • Vegetarians/vegans: plants are low in vitamin D
  • People with a dairy allergy (we shouldn’t really be drinking/eating a lot of dairy anyway)
  • Dark skinned individuals: from melanin reducing their ability for their skin to create Vitamin D

One study showed that elderly people with low levels of Vitamin D are 11x more likely to be depressed than their counterparts who had a normal vitamin D level.  This is because Serotonin, (your happy, mood elevation, hormone) rises when you are exposed to light. [Wilkins, 2006]

You are also much more prone to hip fractures!  Since Vitamin D controls how much Calcium you absorb and how much is in your bones, a lack of it results in easily breakable bones.  Hips get a bad rap here because your femur, thigh bone, bears a lot of your weight when you’re standing.  Hip fractures are common in the elderly for this very reason.

Morale of the story: go outside and get some sun ya damn vampire!


Oh wait, if you unplug from your screen you won’t be able to finish reading the exciting conclusion to our Vitamin D story!

Even though the sun is great, there are other ways…


How Much of the D do I need?

After seeing that sassy salsa dancing old lady and all the literally/figuratively sad stuff that happens if you don’t have Vitamin D, you’re probably headed out to your local vitamin store right now like:


And that’s a good thing! (It’s much better for you than crack).

As I said in the beginning, your body creates it from the sun, which you need about 15-20 minutes per day.

[Warning technical sciencey numbers ahead] The goal is to get about 50-80 ng/ml of Vitamin D circulating in your blood.  Some people can achieve this with as low at 600 IU’s a day, there’s even studies that have shown that this minimal dose had significant reductions in hip and nonvertebral fractures [Murray, 2012]

For general health about 2,000 IU’s is recommended.  For women and men with reduced bone density and pregnant/lactating women that number jumps to about 5,000 IU’s.  The only way to truly know how much your specific requirement is to get blood tested. (Until then just use the above numbers)

IMPORTANT NOTE: Always supplement Vitamin D with Calcium, otherwise you’ll take away from the benefits of taking just Vitamin D.

Another way to supplement is from food.

  • Cod liver oil, oily fish, liver, eggs, and other meats contain Vitamin D.
  • A few plants high in Vitamin D include: Mushrooms (Portabello, Shiitake, Maitake, etc), tofu, dark leafy vegetables.
    • NOTE: Plants have very low levels of Vitamin D, Vitamin D Deficiency is a major problem for Vegans and Vegetarians.
  • Other sources included fortified grains and dairy (but I wouldn’t really recommend that avenue).


Final note: Vitamin D is something you can overdose on.  

Yes you heard me right, it’s possible to have too much Vitamin D.  What this does is put a bunch of Calcium into your blood (hypercalcemia).  This causes poor appetite, nausea and vomiting. Weakness, frequent urination and kidney problems also may occur.

It usually happens from taking too many Vitamin D supplements.  Before you go spitting out all the Vitamin D supplements you just guzzled down ask yourself:

  1. Have I had more than 300,000 IU in the past 24 hours?
  2. OR have you been taking more than 10,000 IU/day for the past 3 months?


Daaaaaayum. That’s a LOT of Vitamin D!

If you were paying attention, remember you only need about 2,000 IU’s a day.  So long as you have some semblance of what you’re putting into your body, you should be fine.


Well my friends, that’s it on Vitamin D.  I hope you learned something and maybe laughed a little in the process.  It’s been a pleasure to guide you down your Vitamin D journey.  At the very least you’ll be thinking this every time the sunlight hits your skin 😉




-Dr. YG



  1. Benettia C et al., Therapeutic Effects of Vitamin D in Asthma and Allergy, Mini Reviews in Medicinal Chemistry,19 May 2015.
  2. Densie Webb, Vitamin D and cancer — evidence suggests this vital nutrient may cut risk, PhD, RD, Today’s Dietitian, Vol. 14 No. 10 P. 58, October 2012, accessed 4 February 2015.
  3. Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, treatment, and prevention of vitamin D deficiency: an endocrine society clinical practice guideline. J Clin Endocrinol Metab 2011; 96: 1911–30.
  4. Mahan, L. Kathleen and Escott-Stump, Sylvia. Krause’s Food & Nutrition Therapy, 12th edition, Saunders Elsevier, St. Louis, MS, Copyright 2008.
  5. Murray, M, Pizzorno J “The Encyclopedia of Natural Medicine” Atria 2012, pg 860.
  6. National Institute of Health “Vitamin D Fact Sheet,” Feb, 2016; Accessed 5/11/16
  7. Type II Diabetes, Vitamin D Council, Accessed 5/11/16.
  8. Ware, Megan “Vitamin D: Health Benefits, Facts, and Research” Medical News Today, April 2016, Accessed 5/11/16
  9. Wilkins, Consuelo H. et al., Vitamin D Deficiency Is Associated With Low Mood and Worse Cognitive Performance in Older Adults, The American Journal of Geriatric Psychiatry , Volume 14 , Issue 12 , 1032 – 1040

***Some sources were used as additional reference and can be found hyperlinked throughout the blog

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