Wear shorts this summer

This week, you learned that vitamin D helps keep women and babies stay healthy. And that it supports your bones. But that’s really just the tip of the iceberg, according Dr. Michael Holick from Boston University’s School of Medicine.

He says vitamin D even affects your genes.

Back in 2006, I delivered the keynote presentation at the Johns Hopkins School of Medicine Continuing Medical Education conference in Baltimore. Dr. Holick gave a presentation at that conference that helped open my eyes about vitamin D.

Dr. Holick is an international expert on vitamin D. And he’s written an informative book on the subject titled, The Vitamin D Solution. At the conference, Dr. Holick warned about the international epidemic of vitamin D deficiency.

You see, vitamin D is an essential vitamin. And it is not made in the body.

You can obtain some vitamin D from your diet. For example, you find it in fish, beef, and eggs. However, very few of us manage to take in enough vitamin D through diet alone.

Fortunately, you can also obtain vitamin D through sun exposure. But first, your body must convert the sunshine into a metabolically active form. This is called photo-conversion. And it’s why I always recommend spending 10 to 15 minutes each day outside in the sunshine without sunscreen. Try to do it every day between April and October. This will help keep your vitamin D at a healthy level.

Unfortunately, the government and misguided dermatologists ruined this simple healthy habit for us years ago. They urge us to stay out of the sun. And never go out without sunscreen.

As a result, too many people don’t get enough vitamin D. And Dr. Holick says this is one reason we face a growing epidemic of medical problems. According to his research, vitamin D helps fend off many different chronic diseases. Such as cancer. And heart disease. And multiple sclerosis.

And at the conference, and ever since, Dr. Holick keeps explaining why vitamin D is so critical to our health.

Yes, it’s an essential vitamin.

But, Dr. Holick says, it really behaves like a hormone in the human body. In fact, it may have been one of the first hormones produced in nature, going back hundreds of millions of years to photozoic plankton.

Dr. Holick and his colleagues are investigating vitamin D’s role as a hormone in cutting- edge genetic research in Boston. Their latest study shows that vitamin D affects gene expression in cells and tissues throughout the body.

Here’s a quick genetics lesson: Genes are the molecular units that contain your DNA. So gene expression involves how your genes communicate their coded information within the cell. Your genes tell your cells which proteins and enzymes to make. And Dr. Holick says vitamin D affects this process.

In fact, Dr. Holick and his colleagues found that a vitamin D deficiency affected the expression of 66 different genes. But taking a vitamin D supplement (400 IU or 2000 IU per day) influenced the expression of 291 different genes. These included genes that helped with DNA repair. And immune response. And response to stress.

These gene functions have a wide variety of biological activities. They act on more than 160 pathways linked to cancer, cardiovascular disease, and autoimmune disorders.

These molecular “fingerprints” uncovered by Dr. Holick and his colleagues help explain all the health benefits of vitamin D beyond the skeleton. And they provide the all-important “mechanism” for skeptics on how vitamin D influences health.

So while we are being inundated by the drug industry with warnings about a supposed epidemic of “low-T,” we should really be concerned about the epidemic of “low-D.”

Just don’t expect your doctor to urge you to spend time outside without sunscreen this summer. Nor will he or she tell you that many drugs–such as ibuprofen–deplete your stores of vitamin D.

But I’ll keep hammering home the point.

I recommend you take at least 1000 IU of vitamin D each day. And now that the sun is high enough in the sky everywhere in the U.S. (even if the air is not yet warm), plan to spend some time outside without sunscreen to “photo-convert” your own vitamin D. And make sure you wear shorts. As Dr. Holick points out…about 18 percent of your skin’s surface is on your legs.


1. Nutrition 4/2013;29(4):605-610.

2. PLoS ONE 8(3): e58725. doi:10.1371/journal.pone.0058725.