Vitamin D’s importance goes far beyond strong bones. We are just beginning to realize we are in the midst of a vitamin D deficiency epidemic, and if you are one of the many who aren’t getting enough, you may be at risk for a variety of major diseases, including osteoporosis, arthritis, and cancer.

Vitamin D is a lot more important than we thought

Have you ever met someone who at first seemed simple and average. Then, as you got to know them better, you began to recognize a deeper wisdom and complexity? Vitamin D is kind of like that. The simpler version of vitamin D we thought we knew is rapidly changing.

In 1921 Sir Edward Mellanby showed that dogs left in the dark developed rickets, and most experts would agree that our first fifty years of acquaintance with vitamin D were rather boring. Its effects seemed rather simple and straightforward. We knew it helped us absorb calcium and phosphorus, so we’d have stronger bones and teeth. Its importance for preventing weak bones (rickets) and osteoporosis motivated our government to mandate its presence in our milk supply, and drinking that milk occasionally was believed to provide enough to keep most of us healthy. Now we know better...

Though it’s still called “vitamin” D, its official designation changed in 1936, when researchers discovered it was a hormone. What’s the difference? Power and leverage. Depth of molecular personality. Vitamins are essential nutrients we can’t make for ourselves. Biochemically speaking, vitamins do their work one molecule or one chemical reaction at a time; they do molecular piece work. Hormones, on the other hand, are more powerful because they act like switches that activate large groups of cellular processes.

For example, suppose you wanted to illuminate a football stadium (this would be your body) for a night game. Adding vitamins would be like turning on one light at a time. Adding a steroid hormone like vitamin D would be similar to turning on all of the lights. The Vitamin D receptors on the surface of each of your cells give this hormonal nutrient the power to initiate transcription of your genes. That’s power!

Don’t let a vitamin D deficiency undermine your health

The latest vitamin D research shows that more than 80% of American don’t get enough. Recent headlines have called attention to the “emerging public health crisis” of vitamin D deficiency which is now believed to cause a “life-threatening impact.” Reports have cited “an alarming prevalence of low circulating levels of Vitamin D in the US population.”

The price of deficiency is now known to be huge: double the risk for all the major cancers, high risk of osteoporosis and immune disease, and accelerated aging--to name just a few.

Knowing your personal vitamin D level is crucial to your long term health. It is more important than, say, knowing your cholesterol number. And bringing your vitamin D up into the optimum range will pay far more health dividends than getting your cholesterol under control.

And it’s easier, too. All you have to do is know the normal range, get tested, take a vitamin D supplement, and get tested again in a month or two to make sure your dose is correct.

What does Vitamin D do in the body?

Vitamin D’s best known effect is to facilitate the absorption of calcium and phosphorus and to regulate calcium homeostasis in the body. Thus it controls skeletal development and is indispensable for maintaining bone mineralization (i.e., osteoporosis prevention). Many studies have reported significant bone benefits from supplemental vitamin D.

Vitamin D is necessary for normal growth in children. In adults it helps with any function that utilizes calcium or phosphorus, such as nerve impulse transmission, the beating of the heart, and blood clotting.

What most people are unaware of, however, is that vitamin D plays several much wider roles, including regulation of blood sugar (important for insulin resistance and diabetes), muscle and connective tissue health, and a strong immune system. And it also is essential to the normal functioning of the gastrointestinal, immune, circulatory, and respiratory systems.

People with higher levels of D are less likely to suffer heart disease, hypertension, inflammatory bowel disease, and autoimmune diseases like type 1 diabetes, rheumatoid arthritis and multiple sclerosis.

But the biggest news of all is D’s cancer protective effect: it helps keep cells from becoming malignant, and when cells do become cancerous, it encourages them to self-destruct.

Take breast cancer for example. "Breast cancer will strike one in eight American women in their lifetime, notes Cedric F. Garland of the Moores Cancer Center, University of California, San Diego. "Early detection using mammography reduces mortality rates by approximately 20 percent. But use of vitamin D might prevent this cancer in the first place." Now generalize this effect to all cancers: "Primary prevention of these cancers has largely been neglected, he suggests, but we now have proof that the incidence of colon, breast, prostate, and ovarian cancer can be reduced dramatically by increasing the public’s intake of vitamin D."

How can you tell if you are low?

The only way to identify a vitamin D deficiency is to get tested. Be sure to ask for a 25-hydroxy vitamin D level. This is a standard test, and any medical lab can do it.

The current RDA of of 200-400 IU per day is woefully small, and supplementing at this level will not be enough for most people. The new recommended supplemental range is 2000-6000 IU daily. But everyone is different, so it is crucial that you get tested to find out the best dose for you. I recommend starting at the relatively low dose of 2000 IU daily. Then, if testing shows you need more, you can ratchet up the dose.

Unlike most nutritional supplements, vitamin D is so inexpensive that there’s no real motivation to cut corners on quality. But you don’t want to be taking handfuls of low potency pills, so find a product that contains 1000 IU per tablet and start at 2 tabs (2000 IU) per day. (You can take them both at the same time if you prefer.)

Then get tested at least a month after starting on this dose. The optimum range for for 25-hydroxy vitamin D is: 45-55 ng/ml. If your level is below this, increase the dose and then retest again after a couple of months.

Please be sure not to confuse this optimum level with the so-called “normal range,” (the one printed in parentheses on the lab report). Doctors and labs are sometimes slow to change, and this is one scary example. The current “normal” lower cutoff point, based on obsolete information, is usually around 20 ng/ml., an unacceptably low level that is associated with a great deal of needless disease. Any level below 30, in fact, is associated with increased risk of cancer, osteoporosis, and immune disease. Make sure you’re up in the 45-55 range.

Too much vitamin D is not a good thing, however, so in the (very unlikely) event that your level creeps up over 70, you need to cut back a tad.

When ultraviolet light from the sun hits our skin cells, they manufacture vitamin D. But sunlight can’t be depended upon as a consistent source of D because it is not always available, varies by season, and is in short supply at higher latitudes. And we all know about the raft of skin cancers that overdosing on ultraviolet rays can cause. Including D in your daily vitamin/mineral supplement program would be a more dependable approach. However, you will need to take your vitamin D separately because the 200-400 IU in your daily multivitamin probably won’t be enough unless you are out in the sun a lot.