Vitamin D – Part 1

Vitamin D is the sunshine vitamin!

Vitamin D has been a hot topic in the nutritional world over the past few years and for good reason. I’ve been reading (and reading and reading) scholarly research documents trying to determine how much merit there is to the fuss. My conclusion? There is a great deal of merit.

Knowing that most of you have no interest in reading (and reading…) scientific literature I have tried to boil down some of what I have read. At times I had to get technical in order to do justice to the information; please stick with me and read all the way through (and come back for part 2). I feel it is extremely important to your health and the health of those you love.

What is vitamin D?

Well, let’s start by saying what it is not – Vitamin D is not a vitamin. Vitamins, by definition, are small compounds which are necessary for health but cannot be synthesized by the body and so must be obtained from the diet. Well, vitamin D is extremely necessary for health, but it can be synthesized by our skin given the right conditions. In fact, with a few exceptions, it is difficult to obtain enough vitamin D from natural sources other than our skin. Vitamin D is, more accurately, the prohormone known as cholecalciferol  – a compound which enzymes in the body later turn into the full-fledged hormone known as calcitriol (or 1a,25(OH)2D3). Calcitriol impacts more than 200 genes.

What is the purpose of vitamin D?

Vitamin D has long been known to be important for bone health. A serious deficiency of the vitamin can cause rickets which is a softening and weakening of the bones. We now know that vitamin D (or really its active form calcitriol) helps to regulate calcium and phosphorus, both important building blocks of bone. It also helps to regulate the body’s ongoing process of breaking down and rebuilding bone.

Recent studies have revealed that there are vitamin D receptors(VDRs) scattered throughout the body. Think of a VDR as a socket designed to hold calcitriol (active vitamin D) so that it can perform whatever function it is designed for at that location. VDRs have been found in the pancreas, pituitary gland, brain, breasts, heart, prostate, the white blood cells of the immune system, and even the hair follicles. (Hmmm – vitamin D to fix my graying hair or my husband’s lack of hair?)

Now my thoughts are – why would God build VDRs into so many organs and tissues if vitamin D was not needed for their function? Think about it. Even if you don’t believe in a creator-God and believe we evolved all of these receptors – there must be a purpose to them. Researchers are now studying the many associations between vitamin D and disease or body functions.

Deficiency or insufficiency of vitamin D is associated with:

  • Osteoporosis
  • Bone fractures in the elderly
  • Muscle weakness
  • Psoriasis
  • Weakened immune system
  • Increased risk of colon, prostate, and breast cancer (and perhaps other cancers)
  • Stunted growth in children
  • Multiple Sclerosis
  • Rheumatoid arthritis and osteoarthritis
  • Type I diabetes
  • Type 2 diabetes and metabolic syndrome
  • Hypertension (high blood pressure)
  • Cardiovascular disease and congestive heart failure
  • Schizophrenia and depression
  • Reduced lung function
  • Crohn’s disease and Inflammatory Bowel Syndrome
  • Tooth decay and gum disease

PLEASE NOTE: The association of two conditions (in this case vitamin D deficiency and a disease) does not necessarily mean that one condition causes the other. For example, while Crohn’s patients tend to have low levels of vitamin D, there are at least three possible explanations: deficiency causes the disease, the disease causes the deficiency (because of poor absorption of nutrients), or a third factor happens to cause both the deficiency and the disease. Also, the deficiency could be caused by low intake or by an impaired ability to utilize what has been ingested or made by the skin. So please don’t run out and start taking high doses of vitamin D without getting a vitamin D test and talking with your doctor.

Coming next: Causes of vitamin D deficiency or insufficiency, recommended levels of vitamin D, and ways to increase your vitamin D levels. Part 2 has now been published! Read it here.

If you would like to dive into my world a little and read some of the reports I have been reading (all of which include references for even more reading), I suggest you start with these:

Related Post:  Vitamin D – Part 2



  1. Amy Jo Sirianni

    Great blog. I have been taking ‘vit. D’ every day, as part of my regiment. I learned how important it is for a healthy immune system. I look forward to the next blog. I never knew it turned into a hormone. Hmmm. No wonder it is so important. You mentioned most of us have no interest in reading research and I think you are right. However, I you and I must have that in common. I love reading research, (not ‘articles’) from all angles, decifering what is truth, and putting the information together in one place. God makes all kinds……. :)

  2. Wilfredo Soule

    You can always get free Vitamin-D by just exposing yourself in the morning sun. The skin can manufacture its own vitamin-d. ..

    Our web blog

    • That depends on where you live, the time of year, and the time of day. Vitamin D forming UVB rays can only penetrate the earth’s atmosphere when the sun is high in the sky. For many of us who live a long way from the equator, the conditions are only right in the middle of the day and only in the summer. By late fall the sun is too low to cause any vitamin D formation. More information can be found in my Vitamin D – part 2 post.

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