How to keep yourself safe from vitamin D deficiency this winter (and all year long)

Last month, I explained how the recommended doses of most nutrients are grossly inadequate. At least when it comes to providing optimum levels that can help protect you from today’s chronic illnesses. And the example of vitamin D is a dramatic illustration of this shortcoming.

Currently, the Institute of Medicine (IOM) recommends 600 international units (IU) of vitamin D daily for adults up to age 70. After age 71, the IOM recommends increasing intake to 800 IU. And a 2011 report by the IOM still holds that most US individuals get “enough” of these 2 nutrients through diet and sun exposure.1

Yet, other current estimates indicate that at least 30 percent and as much as 80 percent of the U.S. population is vitamin D deficient.

And inadequate levels of vitamin D can have some dire consequences. Chronic, debilitating—even deadly— conditions, such as osteoporosis, multiple sclerosis, diabetes, high blood pressure, and cancer (just to name a few).

The good news is there are some easy, effective steps you can take today to make sure your vitamin D levels are healthy. I’ll explain more in just a moment. But first, let’s review some of the reasons vitamin D deficiency is reaching epidemic proportions. And why it should be one of your top priorities—particularly this time of year.

Less sunlight, less vitamin D

To a great extent, your vitamin D level depends on sunlight. Your skin synthesizes vitamin D when it’s exposed to the sun’s ultraviolet B rays.

However, there are a few problems with this process.

First, if you live in northern latitudes, your skin doesn’t make any vitamin D from November through March—no matter how much sun exposure you get. And by “north” I don’t just mean New England…Any latitude above Atlanta is considered “north” for these purposes.

In these areas, the angle of the sun in the sky is too low during the fall and winter to allow ultraviolet B light to penetrate the atmosphere. But even in the late spring, summer, and early fall, UVB from the sun only penetrates the atmosphere and reaches the earth’s surface between 10 a.m. and 3 p.m. So that five-hour window is your only opportunity to “naturally” increase your vitamin D levels.

Knowing this, you might expect that vitamin D deficiency would be a problem in northern latitudes. And, indeed it is.

In Bangor, Maine, researchers found nearly 50 percent of girls ages 9 to 11 years were deficient at the end of winter. And nearly 20 percent remained deficient at the end of summer. At Boston Children’s Hospital, over 50 percent of adolescent girls and black and Hispanic boys were vitamin D deficient year round. In another study in Boston, 34 percent of whites, 40 percent of Hispanics and 84 percent of black adults over age 50 were found to be deficient.

However, vitamin D deficiency is also a national problem. A study published a few years ago in the Archives of Internal Medicine found that at least 75 percent of adults nationwide are vitamin D deficient.2 And the problem has only gotten worse over the past 40 years.

You see, these days, thanks to a concerted campaign by dermatologists, most people avoid what little vitamin-D-producing sun exposure they can get.

The great SPF scam

Years ago, scientists made an association between sun exposure and increased skin cancer risk. Skin cancer is very detectable (since naturally it occurs on the surface of the skin). But rather than taking a sensible approach—just focusing on early detection and treatment of skin cancer—dermatologists began urging people to block out the sun entirely. And today there’s an entire industry built around products that increase your “sun protection factor” (SPF).

A sunscreen with SPF of 8 absorbs 92.5 percent of the sun’s UVB rays. Doubling the SPF to 16 absorbs 99 percent. So while these products might protect you from sunburn, they also essentially shut down your body’s vitamin D production. (I addressed this topic in more detail in the Daily Dispatch “Fresh off the Banana Boat.”)

With all of this in mind, some of the sunniest spots on earth “down under” are adjusting their attitudes and recommendations regarding sun exposure. Both the Australian College of Dermatologists and the Cancer Council of Australia, as well as the New Zealand Bone and Mineral Society, have concluded that we need more of a balance between avoiding skin cancer and achieving enough ultraviolet light to maintain adequate vitamin D levels and help avoid other cancers.

As in all things involving nutrition, achieving a balance is really the right goal and guide for optimal health.

Going to extremes against sun exposure has left far too many people in dire straits when it comes to getting the vitamin D they need to stay healthy.

The fact is, in the summer months, most people should go outside in the sun between 10 a.m. and 3 p.m. in order to get the many benefits of sunlight. It’s best to expose the entire body (wearing just a bathing suit) for 15-20 minutes at least three times per week. (A bit more for African- Americans, since on average, the natural skin pigmentation is roughly equivalent to an SPF of 8 to 15.)

And it should go without saying that this sun exposure should be done without sunscreen. (Although, since you don’t absorb much UVB above the neck anyway, it is a good idea to protect your face and head with a hat and sunglasses.)

Of course, these recommendations are for the summer months. And, right now, fall is just beginning. With a long, dark winter coming our way, what can you do to protect your precious vitamin D stores over the cold months ahead?

Well, one option is to get UVB exposure from a tanning bed. (Three times per week.) But this isn’t always practical.

Unfortunately, neither is getting your vitamin D from food.

Even “fortified” foods fall short

There is essentially little or no active vitamin D available from regular dietary sources. The most common sources are fortified foods like milk and orange juice. But one glass of milk or fortified orange juice only contains about 100 IU of vitamin D. So you would need to drink quite a bit of it to reach even the RDA amount (which, as we’ve already established, isn’t optimal). Again, not very practical.

Salmon does contain available vitamin D. But it must be wild caught salmon. These fish feed on phytoplankton and zooplankton, which make their own vitamin D. Farmed salmon, on the other hand, are fed food pellets with little nutritional value.

As a consequence, they have only 10 percent of the vitamin D of their wild counterparts.

But salmon isn’t an adequate source of vitamin D by itself. A 9 oz. serving contains just under 1,000 IU. A good start, but I don’t know how many people that would be willing or able to eat that much on a daily basis.

So the best solution for maintaining adequate vitamin D levels is to take a quality nutritional supplement.

Which brings us back full circle, to the question the so-called government health “experts” can’t seem to answer correctly…

How much vitamin D do you need?

If all you want to do is prevent outright deficiency, by all means, stick with the 400-600 IU RDA of vitamin D. Just don’t expect it to do much more than protect you from rickets. But if you want to make sure you’re getting all the protective benefits this nutrient has to offer at optimal levels (prevention of MS, osteoporosis, cancer, etc.), you’ll need much more.

Currently, experts here in Boston, where vitamin D deficiency is a serious problem, recommend 1,000 IU daily for both children and adults. Still, some experts view even this dose as too low. In fact, many physicians are beginning to recommend much higher supplement doses. Often 2,000 IU per day. And given that people metabolize nutrients differently, it’s not unreasonable to recommend as much as 5,000 IU per day for some people (based upon medical evaluation by a physician knowledgeable of the problem).

There’s also a pharmaceutical-grade preparation of vitamin D available. Of course, you will need a doctor’s assistance not only to get it, but to administer it as well. One caveat about this particular preparation: It comes in 50,000 IU doses. So the therapeutic regimen isn’t the same as a daily vitamin supplement. In this case, you would take 50,000 IU once per week for 8 weeks to treat deficiency. After that, the dose is 50,000 IU every two weeks to maintain vitamin D levels.

Whatever approach you choose, it’s important to work with a physician knowledgeable about nutrition. One who understands your needs as an individual and can help you tailor a supplement program that will help you reach optimal vitamin D levels safely and effectively.


SB: Too much of a good thing?

Of course, the big concern with higher doses is the risk of vitamin D toxicity. This always strikes me as more than a little ironic. The medical establishment doles out dangerous and expensive drugs like candy. Yet they’re constantly—and vehemently—concerned about the potential “risks” of physiologic levels of natural substances such as vitamins (and even sunlight).

The fact is, it’s practically impossible to reach “toxic” levels of vitamin D. Especially from too much sunlight. (Sunlight actually destroys excess vitamin D that is made in the body.)

The only time vitamin D can cause problems is in cases of chronic disorders such as histoplasmosis, sarcoidosis, or tuberculosis. In these instances,blood levels of vitamin D above 30 ng/ml may cause dangerously high levels of calcium in the blood and urine. But there are really the only cases in which supplementation should be avoided.


1.  Slomski A. JAMA. 2011;305[5]:453-456 2  “Demographic Differences and Trends of Vitamin D Insufficiency in the US Population, 1988-2004” Arch Intern Med. 2009;169(6):626-632