Do you need more Vitamin D?

Are you down with the D? Vitamin D, that is. What does D do? Do you have enough? Could you use more? I’ll try to answer all these questions and more. First, a look at vitamin D’s basic functions and how we get it. Then, we’ll consider its relationship to specific populations and dangers in deficiency.
Vitamin D is both a vitamin and a hormone.

It is a fat soluble vitamin because we can absorb it from our food ONLY in the presence of fat (i.e. meat, olive oil, butter, etc.).

It is a hormone too, meaning we can make it in our bodies and it affects other tissues.

We get two types of Vitamin D from our diets, D2 and D3. Vitamin D2 is manufactured and often found in fortified milks, cereals, and breads while vitamin D3 is found in oily fish like salmon and mackerel and also in eggs. Although many claim that vitamin D2 is inferior to D3, I will show you that this is not necessarily true.

We also absorb Vitamin D from sunshine which puts a very interesting twist in the mix with the rise in sunscreen use and abuse. Sunshine should be our main source of vitamin D, yet sunshine doesn’t sell. Sunscreen does. Even the lowest of SPF’s block out most of the UVB rays that are responsible for producing vitamin D.

Sunshine is a controversial subject, but I will quickly note that people who live closer to the equator have significantly less incidence of cancers (e.g. testicular, ovarian, etc.), heart disease, and a lower blood pressure than populations who live further away from the equator. It is also important to note that most malignant and fatal skin cancers are suffered by people who spend the least amount of time in the sun (i.e. desk jobs instead of carpentry).

Spend time in the sun without sunscreen. You’ll live longer… disease-free.

Moving on…

In our bodies, vitamin D must be activated to work. Our kidneys and liver are responsible for the activated vitamin D in our blood. Every cell in our body can activate its own vitamin D as needed, however, making this vitamin/hormone very interesting indeed. Because of this factor the activated vitamin D in our blood works primarily in the intestines to aid in calcium absorption.

Bone health is the often advertised benefit of adequate levels of vitamin D, but vitamin D also regulates cell growth. As we will see, this function has important implications in the development and spread of cancer. Vitamin D is also necessary for proper neuromuscular function, your nerves and muscles working together.

Vitamin D is vital for calcium absorption. No matter how much calcium is consumed, we CANNOT absorb much of it without adequate vitamin D. This means that you can drink all the fortified milk you want, take your One-A-Day and stuff your face with greens, but if you’re D-deficient, it’s like you ate little to no calcium at all. In a D-deficient state the intestines only absorb 10-15% of ingested calcium while they absorb 30-40% with adequate vitamin D. (Holick) Match that with a diet of calcium-leaching breads, pastas, and cereals and you have double trouble.

In summary, vitamin D is so essential that we can get it from food, sunshine AND each cell in our bodies can manufacture it as needed. Bone health is a primary function of vitamin D, but it also plays important roles in neuromuscular function and cell growth. On calcium absorption, we cannot absorb dietary calcium without adequate levels of vitamin D. The bottom line? Consider a Vitamin D supplement in the winter and getting “safe sun” in the sunny months!

What do you think? Comment below!


  • joyce

    Reply Reply June 1, 2011

    Hey Gerilyn, Thanks for all the info. I recently had a physical and discovered that I have very low vitamin D. The doctor prescribed a mega-dose to be followed by daily dose from now on, plus calcium. Interesting what you mentioned about D2 because I had someone in the health-food store tell me that D2 is useless and does nothing for the body and don’t bother taking what the dr. prescribed!

    • gerilyn

      Reply Reply June 2, 2011

      Sure Joyce! Yes, I had believed that too for awhile, until I read Dr. Holick’s clinical research. I feel like the health food store people mean well, but don’t read anything that’s not anecdotal and/or refuse to believe evidence in the face of long-held traditional beliefs… similar to religion, sometimes 😉

  • Angie

    Reply Reply June 2, 2011

    Great information! I didn’t know there were two types. I’ve been making sure to get plenty of sunshine 😉 If not, I’ve got vitamin D on standby. I love reading your posts… I always learn something new.

    • gerilyn

      Reply Reply June 2, 2011

      Hi Angie! Sunshine is awesome! I appreciate your comments and thoughtful insights! 🙂

Leave A Response

* Denotes Required Field