Low Vitamin D Levels and Cancer

Several years ago researchers discovered that women with breast cancer had much lower blood levels of Vitamin D than women without breast cancer.  Another study showed that, among women being treated for breast cancer, those with low Vitamin D levels were only half as likely to survive.  Patients with other cancers show similar patterns.

Now we have a study which points out that this does not prove that low Vitamin D causes cancer.  True.  The new theory is that cancer causes low Vitamin D levels.  However, there is no proof of that either, and I find it hard to believe.  What does this all mean?

What we have is an association of low Vitamin D levels with many disease states. These include:  low Bone Mineral Density, higher Fracture Risk, Depression, Winter Blues, Nerve Pain, Fibromyalgia, MS, numerous Auto-Immune Disorders, Secondary HyperParathyroidism, and several Cancers.

We know that giving high-enough dose Vitamin D3 often cures the Winter Blues and can improve most of the other disease states on the list.  We cannot prove that low Vitamin D levels cause any of these problems without a randomized, prospective, placebo controlled, multiyear study involving tens of thousands of people. This will never happen.  Why?

I would not volunteer for a study to prove that if I keep my Vitamin D level low enough for long enough that I will develope any of these diseases.  It is not ethical to ask others to do so.  Therefore we are stuck having to rely on “observational” studies looking for strong associations.

Personnaly, I simply keep my 25-hydroxy Vitamin D level above 40.  It can’t hurt, and it probably will help.

Jay Ginther, MD

Categorised in: Nutrition