Chapter 15

Ten Myths Regarding Vitamin D

In This Chapter

Regarding vitamin D as a vitamin

Getting vitamin D in your diet

Staying out of the sun

Taking too much vitamin D

Getting vitamin D in breast milk

Poor vitamin D needs psychotherapy. It’s so misunderstood. Thanks to some medical specialists, we’ve avoided the sun like the plague, thereby keeping our bodies from making sufficient quantities of vitamin D naturally. As a result we may have put a lot of folks at increased risk for osteoporosis — and if the early research holds up — for heart disease, cancer, immune diseases, and diabetes, too. Only in the last 30 years have we begun to fully understand the power of this amazing substance. So many myths surround vitamin D that I could easily double or triple this chapter in the Part of Tens.

Well, there’s no point in playing the blame game. The damage has been done, and we need to repair it. It’s time to set the facts straight and correct some misconceptions and half-truths.

Myth: Vitamin D Is a Vitamin

Calling vitamin D a “vitamin” is like calling Abraham Lincoln a politician. Vitamin D is so much more than a vitamin.

Vitamins are essential chemicals that you have to consume if you want to live — you can’t make them. But depending upon where you live, you don’t have to eat vitamin D to live. Human skin has been manufacturing vitamin D since the first human walked the Earth. And curiously, our bodies make just the right amount for our needs and then shut off further production. So in that sense, vitamin D would be better called a “conditional” vitamin D — under conditions where you don’t get enough sun, you have a vitamin D requirement.

It’s also important to remember that the form of vitamin D that the skin makes isn’t the active form. Vitamin D by itself does absolutely nothing; it’s inert. Vitamin D from the skin or diet must tour the body, first stopping at the liver to become 25-hydroxyvitamin D and then going to the kidneys, where it becomes the active form of vitamin D, 1,25-dihydroxyvitamin D, or calcitriol (see Chapter 1 for more info). Calcitriol then leaves the kidneys through the blood stream to do its work to regulate how the body uses calcium.

A substance that is made in one organ and travels in the blood to do its work in other organs is the definition of a hormone, so is vitamin D a hormone? No, because the vitamin D you consume or make in your skin isn’t a hormone until the body converts it to one; it’s a half truth to call vitamin D a hormone. In contrast, calcitriol, the active form of vitamin D, fits the definition.

Myth: You Can Get Sufficient Vitamin D in Your Diet

First, the word “sufficient” needs to be defined. The recent Institute of Medicine expert panel defined “sufficient” as the intake level necessary to maintain a blood level of 25-hydroxyvitamin D of 20 ng/ml (50 nmol/L) or more. The panel determined that it takes about 600 to 800 IU of vitamin D a day to make sure your blood levels are consistently this high. Some people look at the studies showing a protective association between even higher serum 25-hydroxyvitamin D levels (up to 40 ng/ml or 100 nmol/L) and chronic diseases and believe that 1,500 or more IU of vitamin D are needed per day for “sufficient” serum 25-hydroxyvitamin D levels.

Survey data from the United States and Canada show that the aver-age 25-hydroxyvitamin D levels are 24 to 26 ng/ml (60 to 65 nmol/L). About 75 percent of Americans and Canadians are already reaching the target level of more than 20 ng/ml (50 nmol/L). Still, most North Americans are getting only 200 to 280 IU of vitamin D daily through diet, so they must be attaining their 25-hydroxyvitamin D level through sunlight exposure.

But don’t be completely reassured by that survey data. At least 25 percent of North Americans are not reaching the target serum 25-hydroxyvitamin D level. The percentages are even worse when the effects of increasing skin pigmentation are considered; while about 20 percent of Caucasians are below target, among Mexican Americans it’s about 40 percent, and among African Americans it’s about 60 to 70 percent who fall below the target.

In Chapter 12, I discuss all the foods that can give you any reasonable amount of vitamin D. Unless you’re a small child (and I doubt any small children are reading this), it seems unlikely that you can get enough vitamin D from foods to reach serum levels of 25-hydroxyvitamin D of 20 ng/ml (50 nmol/L) much less higher levels. So unless you’re living in the far North and consuming a traditional diet rich in blubber from seals and whales, you can’t do it. People just don’t eat vitamin D–rich fatty fish every day, and few people want to drink six or more cups of milk a day. This means that unless you can get exposed to UVB, you need a vitamin D supplement.

Myth: You Should Avoid the Sun at All Costs

Dermatologists believe that sun exposure of any amount causes most, if not all, of the skin damage that leads to

Precancerous and cancerous lesions of the skin, including basal cell carcinomas, squamous cell carcinomas, and malignant melanomas

Benign tumors

Wrinkles

Freckles

Most people need very little exposure to UVB light to meet their vitamin D needs. So is there enough reason to completely avoid the sun? I don’t think so.

The other argument to use the sun for vitamin D is that the benefits may outweigh the risks. We know that vitamin D is important for bone health, and the data is getting stronger that adequate vitamin D stores are needed to prevent cancer, autoimmune diseases, and heart disease. Are you going to stay out of the sun even if it means you could die early of a cancer, an autoimmune disease, or heart disease? What are you avoiding when you avoid sun exposure? The main issues to worry about are skin cancer and malignant melanoma.

In the United States, 3.5 million skin cancers are diagnosed annually. Skin cancer causes just 2,000 deaths each year, many of them due to simple neglect. Most of them are on the face and highly visible; the patients typically just didn’t bother to see the doctor when the skin cancer first appeared and was treatable.

Malignant melanoma is another story. In 2010 in the United States, 115,000 new cases of malignant melanoma were diagnosed. The same year, 8,700 people died from malignant melanoma.

But does sunlight cause malignant melanoma? It certainly plays a role, but many melanomas occur in skin that hasn’t been exposed to sunlight. Melanoma runs in families and occurs in people with compromised immune systems.

In addition, the number of deaths from cancers involving organs that vitamin D may protect against will be 280,000 in 2010. Some estimate that as many as 50 percent of these cancers could be prevented by optimizing vitamin D status. That’s probably optimistic (we don’t get 100 percent compliance for any health recommendations, and it seems too good to be true that vitamin D — through calcitriol — could be that potent). But if increasing vitamin D status could prevent 20 percent of those cancers, we could save 56,000 people a year. That number doesn’t even take into account all the other diseases that vitamin D protects against.

I believe that the amount of sun you need to make your vitamin D requirement (about 6 to 20 minutes) is safe (remember that the actual amount will vary by your skin tone, season, and geography). Certainly, protect yourself against skin damage and skin cancer, but allow yourself the right amount of sun exposure to maximize your health with vitamin D. See Chapter 11 for everything you need to know to get a healthy dose of the sun.

Myth: It’s Easy to Take Too Much Vitamin D

This myth has a grain of truth to it.

Most of the known examples of vitamin D toxicity happen because of stupidity. Suppose someone ignores directions and adds way too much vitamin D into milk; suppose someone steals the vitamin D used to supplement milk and uses it as a cooking oil; or suppose someone is taking ounces of a vitamin D supplement instead of just drops — you get the point.

Some of the current liquid vitamin D preparations for babies or toddlers can expose them to the risk of vitamin D toxicity if they’re given the wrong amount. Manufacturers make the preparation so that as little as a drop contains 400 IU of vitamin D. Other manufacturers make it so that 2 teaspoons contain 400 IU of vitamin D. If the babysitter gives an incorrect amount of a preparation, a child could easily get a giant dose of vitamin D. But a one-time giant dose probably won’t hurt anyone; only administering the wrong giant dose day after day causes damage.

Adults find it difficult to take too much vitamin D. In some studies, adults have been given 100,000 IU per week for many weeks with no signs of toxicity. The current recommended upper safe limit of 4,000 IU per day isn’t close to that amount.

If you’re regularly taking a large amount of vitamin D as a supplement and you’re worried about toxicity, get your blood calcium level tested. As long as the calcium stays normal, you’re free of toxicity. (An elevated calcium [hypercalcemia] is greater than 11 mg/dl or 2.75 mmol/l, depending upon the laboratory.) The main symptoms of hypercalcemia are fatigue, malaise, aches, loss of appetite, nausea, and vomiting. With even higher serum calcium levels, symptoms similar to uncontrolled diabetes develop with excessive thirst and urination, dehydration, and drowsiness leading to confusion and even coma.

You can also get an occasional blood level of 25-hydroxyvitamin D. Experts believe that a level greater than 100 ng/ml or 250 nmol/L is a toxic level of vitamin D that can lead to hypercalcemia.

Myth: Government Guidelines for Vitamin D Intake Are Inadequate

Some people believe that if you want to suffer from vitamin D insufficiency, follow the government recommendations. However, the new vitamin D requirements that were announced in November of 2010 are based on a careful assessment of all the available research. The new report clearly explains all the positions and assumptions taken by the committee and it directly explains why the committee wasn’t convinced by some of the data used by its critics. If you believe in the concept of evidence-based medicine, you should accept the new vitamin D requirements.

Although the Institute of Medicine expert panel didn’t think there was enough evidence on vitamin D and nonbone disease to set a requirement, they didn’t close the book on this issue. In fact they strongly urged that more research be done to determine which nonbone effects of vitamin D are real, and what vitamin D intake or blood levels of 25-hydroxyvitamin D are needed to achieve these effects. The evidence-based medicine approach lets us accept any new research studies and change the recommendations when the information becomes available.

Myth: You Need Vitamin D Only for Your Bones

If you’ve read just about any other chapter in this book, you know how much of a myth this statement is. The original function described for active vitamin D (calcitriol) was to facilitate the absorption of calcium for the building of bone, but since about 1980, numerous other purposes have been discovered. Some of them are still tenuous, based only on associations between serum 25-hydroxyvitamin D levels or geographic location and the health outcome. However, for others the evidence is growing stronger as new studies come out and as clinical trials are initiated.

A short list of other conditions in which vitamin D may play a role includes the following:

Protecting against autoimmune diseases, including multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosis, hyperthyroidism, and type 1 diabetes (see Chapters 5 and 8)

Protecting against and treatment for tuberculosis and other infections (see Chapter 5)

Preventing cancer, including breast, prostate, colorectal, and possibly other cancers (see Chapter 6)

Guarding the heart against heart attacks and heart failure (see Chapter 7)

Avoiding type 2 diabetes and metabolic syndrome (see Chapter 8)

Possibly blocking Parkinson’s disease, Alzheimer’s disease, depression, and autism (see Chapter 9)

I feel certain that the list will get a lot longer, but this is more than enough reason for you to be sure that you get your daily dose of vitamin D, one way or another.

Myth: Children Get Enough Vitamin D in Breast Milk

Many advocates of breastfeeding view breast milk as a perfect food. However, breast milk normally contains very little vitamin D, especially when 25-hydroxyvitamin D blood levels are in the target range of a little more than 20 ng/ml or 50 nmol/L. In contrast, a small clinical trial of 19 women suggested that if a woman takes about 6,400 IU per day she will have a 25-hydroxyvitamin D level of about 64 ng/ml or 160 nmol/L, and enough vitamin D is then present in the milk to give the baby target levels of 25-hydroxyvitamin D. This high-dose approach isn’t recommended for everyone because it has only been formally tested in that small, pilot study, and so the benefits and risks of this method aren’t known for certain. For the average breastfeeding woman, it’s best assumed that there isn’t enough vitamin D in milk and that the baby should receive vitamin D drops directly.

Women who want to get pregnant are advised to make sure their vitamin D intake (and possibly the 25-hydroxyvitamin D blood level) is satisfactory before conceiving. Women who are nursing can increase their breast milk vitamin D levels only by taking large vitamin D supplement levels (about 6,000 IU per day). For mothers who don’t take these large supplements, they should use a vitamin D supplement designed for infants to make sure their babies have adequate vitamin D status.

Myth: You Protect Your Skin Completely with Sunscreen

This statement is true only if a person uses sunscreens correctly. Unfortunately, many people don’t do that — they apply too thin a layer and they forget to reapply it after a couple of hours.

To be certain that your sunscreen is effective, follow these rules:

Check your skin type (see Chapter 11), and make sure that the skin protection factor (SPF) number is enough for your skin. A number of 30 or greater is usually enough; the numbers above 30 get progressively more expensive.

Make sure you apply enough sunscreen. People tend to skimp on sunscreen because they don’t like how it feels.

Reapply every two hours.

Reapply if you sweat or swim.

Don’t forget that a little sun exposure, as outlined in Chapter 11, can make sure you have enough vitamin D. Take a supplement if you live at latitudes from San Francisco and higher in the winter.

Myth: A Tanning Salon Is a Safe Way to Expose Your Skin

When most people go to tanning salons, they don’t go to get their vitamin D fix — they go to achieve the skin color of a bronze god or goddess. If you have a tan, you’ve done damage to your skin. The tan is your skin’s way of protecting itself from further damage.

Most people who go to tanning salons sit under the light for long enough to burn to set a “foundation” for further tanning. They may do this several times a year to achieve their bronze color. This results in damage to the skin and potential skin cancer. The long delay (years) between the salon and the cancer makes people think frequenting tanning salons is safe, but it isn’t.

The light used in a tanning salon has more ultraviolet A energy than you get from sunlight. It causes premature wrinkling and contributes to skin cancer. And depending upon the lamps that the tanning salon uses, there may be no UVB at all, meaning that the tanning bed won’t help you make any vitamin D. Beware of false advertising by salons which claim to help you make vitamin D when their lamps emit only UVA.

Research has shown that tanning beds with UVB (but not UVA) can be used to make vitamin D in the skin; however, in the summer the sun is free, and in the winter a vitamin D supplement is cheaper than the cost of regular tanning bed use.

Tanning salons are not good for your skin in any way, and I recommend that you not use them. A tanning salon provides the same kind of benefit for your skin as a cigarette provides for your lungs.

Myth: Vitamin D Is the Cause for Elevated Serum Calcium

Although it’s true that vitamin D toxicity causes elevated serum calcium, it takes a lot of vitamin D to do this. You may have an elevated serum calcium level for many other reasons, including:

Primary hyperparathyroidism, in which the parathyroid gland has a tumor and produces too much parathyroid hormone, raising the calcium by breaking down bone

Cancer, by producing a compound that acts like the parathyroid hormone to stimulate its breakdown, or by the cancer directly eroding into bone

Other diseases, such as tuberculosis or sarcoidosis, an inflammatory disease that often begins in the lungs, by increasing the body levels of calcitriol from locations other than the kidneys

The fact is that vitamin D is quite safe and only elevates serum calcium if really high vitamin D levels are consumed daily for many weeks.

What is less certain is whether intermediate 25-hydroxyvitamin D levels between about 50 ng/ml (125 nmol/L) to 100 ng/ml (250 nmol/L) may lead to other chronic complications. As mentioned earlier in this book, some associational studies have suggested that mortality, certain cancers, and cardiovascular disease might actually increase with levels in this range. This is why the Institute of Medicine committee urged caution against thinking “more is better” with respect to vitamin D intake and 25-hydroxyvitamin D levels. We need more research to know what the truly desirable target range is. Right now we know levels greater than 20 ng/ml (50 nmol/L) optimize bone health, and levels higher than 100 ng/ml (250 nmol/L) cause high blood calcium; we don’t know for certain what additional benefits or adverse effects might occur in between those values.