The disease called winter: Risk of heart disease and vitamin D

by Dr. John Whitcomb, Medical Director, Aurora Sinai Medical Center Wellness Institute

Winter is dark and cold. We bravely face it here in Wisconsin, making the best we can do with the state we are in. But deep down inside, our souls just yearn for a nice warm, sunny day. Intuitively, we have this vague feeling that winter just isn't good for us.

What we do know scientifically is that from about Oct. 15 to April 1, the angle of the sun is so low in Wisconsin, that your skin cannot make vitamin D, no matter how hard you try. In late December, the angle is about 24 degrees. For six months we coast on our reserves from summer, with a tiny addition from the milk we drink and the multivitamin we take. Nothing dramatic, but year after year we do it again and again...

Now the proof is here. This study about heart attack risk and vitamin D is a landmark study. From the Framingham cohort of patients, now followed for over 50 years, 1,739 patients without heart disease were followed and separated into groups by their natural levels of vitamin D. Those folks with vitamin D below 15 ng (28 percent of the sample group) had a 62 percent "hazard ratio" (a.k.a. greater risk) and those folks with vitamin D below 15 ng andhigh blood pressure had a 2.12 "hazard ratio."

This is stunning. It adds to the growing body of evidence that the human species was not designed to live outside of sunshine. Vitamin D is important to every cell in our bodies. It essentially works as a hormone, not a vitamin, to tell our cells to grow up into their intended function. That happens to blood vessel cells just like any other. When they are well, they don't get fatty plaques and respond well to blood pressure challenges, just like they were designed to do.

The scientific language says it this way: "1,25 dihydroxyvitamin D directly suppresses renin gene expression, regulates the growth and proliferation of vascular smooth muscle cells and cardiomyocytes, and inhibits cytokine release from lymphocytes."

What Dr. Wang and his colleagues at Harvard found in the Framingham cohort of patients is observational data (not a randomized controlled trial, but a prospective observational trial). This makes vitamin D deficiency to be almost as powerful a risk factor as high cholesterol, smoking and high blood pressure. The study wasn't large enough to detect if medium deficiency was also dangerous. 15 ng is what 28 percent of the population has, and very likely what many of us in Wisconsin have in mid-winter.

That suggests that each winter each of us goes through a five to six month stress test during which time our bodies have inadequate amounts of vitamin D for optimal health. We don't have any disease state from it that can be detected in one winter. Instead, each year, winter after winter, our blood vessels are in a state of stress, just like all the other cells in our bodies that need vitamin D to reach optimal health (so far 1,400 different types). Then we recover for the summer.

And after 30-40 years, we are in a condition where the other risk factors for heart disease take over, like high cholesterol, high blood pressure, etc. And we ask, "What went wrong? What could I have done?"

This is plausible! The cellular mechanisms are understood and make sense. The cell types that make up our arteries and heart have vitamin D receptors. Vitamin D has been shown to reduce blood pressure, all by its self, and is therefore known to be active in our vascular system. What we need now is a prospective, randomized controlled trial to test whether an intervention will work at reducing the risk. That will take lots of time. Is it risky to take vitamin D in the meantime?

Is winter a disease? It certainly is a physiologic stress test, one that optimal health would argue we can do something about. Now we got the details.

What will work for me?

We were designed to live in sunshine. A five month period of time deprived of sunlight is not to our best advantage. I measured my own blood level of vitamin D on 2,000 U a day and found it to be 25 ng. in early December. That's after living in Wisconsin for four months without a vacation to any place sunny and being essentially indoors. And that's with a supplement.

Not a rock bottom number but lower than I want. I want at least 30, so I raised my supplement dose to 5,000 U a day. After a month, my level came back at 35.4 ng. Not toxic. The upper limit of normal is 52 ng/mL.

If there is anyone out there that you know that isn't taking vitamin D during the winter, especially if they have high blood pressure, talk to them. Encourage them to see their doctor and ask about a vitamin D blood level. I'm sure this will become part of our standard risk assessment for heart disease and just plain general health.

So, get out there and schedule your trip to Disney World, Fort Myers Beach, Cancun, or 10 minutes in the tanning booth three times over the next two weeks. Short of that, a cheap vitamin D pill and a beautiful poster... till April. Then, like Grandma said, "Go play outdoors." Your heart will benefit and thank you.

Reference: Circulation 2008: 111 Wang et al from Mass General and Framingham Study