Chapter 13

Getting Vitamin D from Supplements

In This Chapter

Choosing the best vitamin D supplement

Taking the supplement correctly

Determining the supplement’s effect on blood levels

Taking a supplement is definitely the second-easiest way to build up your vitamin D level. The easiest, described in Chapter 11, is to walk outside in the sun for a few minutes three times a week. This plan doesn’t work for some latitudes and during some seasons, however. And some people can’t expose themselves to the sun for health or religious reasons (like devout Muslim women who are fully covered with burkas). And dermatologists caution us about getting any sun exposure because of the perceived risks of developing skin cancer. In these cases, you need to take a supplement.

Now that vitamin D is such a hot commodity, different preparations are becoming available. Unfortunately, the price is also going up. But vitamin D still may be the biggest health bargain around: In many pharmacies, vitamin D sells for a few pennies for 2,000 IU.

That’s good news and bad news. It’s good news because inexpensive vitamin D is probably the biggest health bang you can get for your buck. It’s bad news because drug manufacturers aren’t going to put a lot of effort into making newer and better preparations if they get no more than a few cents’ profit.

In this chapter, I tell you everything you need to know about the current supplements. More are coming on the market every day. I even provide the latest prices, but I doubt that those prices will hold. You can count on prices for vitamin D going up, but most stores will probably maintain their price with respect to other stores. In other words, if they’re the cheapest now, they’ll remain the cheapest, but at a higher price.

Choosing the Best Supplement

When you go to the pharmacy section of your local drug store and stand in front of the vitamin section, you may be stunned by what you see — row after row of vitamins and minerals in all sizes of bottles. Don’t be overwhelmed. Depending on their age, most healthy adults only need 600 or 800 IU a day. That means you can choose to take a multivitamin and mineral supplement that has this amount in it, you can take a combined vitamin D and calcium supplement, or you can take a dedicated vitamin D supplement. If you focus only on the bottles of vitamin D supplements, you may see several choices among that one vitamin. That’s because supplements are now available in many different forms and many different strengths.

In the following sections, I explain the differences between the various forms of vitamin D, provide my recommendations on how much vitamin D your supplement should contain, and then offer a comparison of vitamin D supplements that are on the market at the time of this writing.

Deciding what to take

The different forms of vitamin D are as follows:

Cholecalciferol is vitamin D3. This is the form that’s made in your skin by the sun or any ultraviolet B rays.

Ergocalciferol is vitamin D2. This is the form also made in certain yeasts and mushrooms from the sun or UVB rays, but what’s in the supplement is chemically synthesized. It can be as effective as vitamin D3.

Calcidiol is the next step after the formation of vitamin D3. It’s 25-hydroxyvitamin D. This form isn’t available as an over-the-counter supplement.

Calcitriol is the active form of vitamin D3. This is a hormone and is regulated by the Food and Drug Administration and Health Canada as a drug. It’s very potent, so you wouldn’t want to take it anyway.

The form that you want to take is the one most like the form you make in your skin: vitamin D3, or cholecalciferol. The supplement is formed by extracting 7-dehydrocholesterol from the wool of sheep. The extract is extensively purified, dissolved in a liquid, and treated with ultraviolet light to make cholecalciferol. This vitamin D3 is further purified to make the supplement you take.

Choosing a multivitamin, mineral, or targeted supplement

Many people choose to take a multivitamin and mineral supplement because they get all or most of what they need for all of the required micronutrients in one pill. Only the minerals that are required in large amounts like calcium and phosphorus are provided in levels less than the current recommendations. (That would make the pill too large.) You would want to avoid vitamin D in these formulations only if you want to take more vitamin D or if you want a targeted supplement. There are many good multivitamin and mineral supplements, so I won’t make a specific recommendation. Just read the label and make sure whatever you choose has at least 75 percent of the recommended levels of all the essential nutrients.

Taking more than one multivitamin per day to get higher doses of vitamin D may give you a toxic dose of another vitamin, particularly vitamin A.

Solid pill supplements are held together with binders. These binders are usually proprietary so you can’t tell exactly what they are. Some people find that certain binders upset their stomach. If you try a supplement with a binder that does that, try another brand.

Many women like to take a supplement that combines calcium and vitamin D to protect their bones. These supplements usually supply about half the daily requirement of calcium combined with half or more of the vitamin D requirement. As I mentioned in Chapter 3, women are encouraged to take these smaller calcium doses with every meal to improve their absorption of the calcium. Table 13-1 lists a few of these supplements.

Deciding how much to take

In an ideal world, you’d get your 5 minutes of sun each day and you wouldn’t need to take a supplement at all. In fact, the average serum 25-hydroxyvitamin D levels in the United States (about 25 ng/ml or 62.5 nmol/L) suggest we might be doing just that, at least during the summer. Still, there are several groups that don’t reach 20 ng/ml (50 nmol/L): Northerners in winter, African Americans, institutionalized elderly, and so on. Regardless of who you are, if your serum 25-hydroxyvitamin D is less than 20 ng/ml (50 nmol/L) and you don’t eat vitamin D–rich foods or get sufficient sun exposure, you need to take a supplement. Deciding how much to take is the next step.

In Chapter 2, I told you about the vitamin D requirements set by an expert committee from the Food and Nutrition Board of the Institute of Medicine in the U.S. National Academies of Science (I know . . . that’s a mouthful!). This group felt that the scientific evidence supported the need to get serum 25-hydroxyvitamin D to 20 ng/ml (50 nmol/L) or above and they thought studies supported a level of 600 to 800 IU per day to get there in most healthy adults.

Other scientists think that we need to raise our serum 25-hydroxyvitamin D levels to 30 ng/ml (75 nmol/L) or more to get all the health benefits from vitamin D. They base their opinion on a number of studies that show an association between blood vitamin D levels and health outcomes such as cancer or diabetes. If they’re right, an adult would need 1,600 IU to reach 30 ng/ml (75 nmol/L) or 3,000 IU to reach 40 ng/ml (100 nmol/L). The scientific validity of these recommendations isn’t fully established, but because they’re under the current recommendation for the upper limit, some people are choosing to take more vitamin D now rather than wait for what the studies have to say.

Aging doesn’t affect the body’s ability to absorb vitamin D. The reason for the higher dose for those 70 and older is the much greater tendency for older individuals to avoid any sun exposure.

Comparing the different preparations of vitamin D

Many preparations of vitamin D are on the market today, and more are showing up each day. Unfortunately, you can’t be sure of the quality of the capsule, pill, or liquid because these preparations aren’t considered drugs and don’t have to pass the stringent rules of the Food and Drug Administration.

The preparations I discuss here all come from respected companies and can generally be relied upon to contain at least what they promise, if not a little more. In fact, all supplements are manufactured with the intent to have up to 25 percent more than the stated amount in order to allow for some deterioration in the vitamin D content during the shelf life of the supplement. In any case, you may want to have your 25-hydroxyvitamin D levels measured after you have been on a supplement for several months to verify that you are achieving the desired blood levels.

Sometimes a vitamin D capsule has other ingredients, like omega-3 fatty acids. This explains some of the discrepancy in price, but I think you’ll be as bewildered as I was by the difference in price for the same amount of vitamin D in the different preparations.

In Table 13-2, I list some common brands of vitamin D supplements available in the United States. You can see at a glance the variation in international units (IUs) and price. To help you compare apples to apples, I also have included the cost for the 1.2 million IU that one bottle of Costco Kirkland vitamin D3 provides. These prices have been taken from advertisements on the Internet, so should be considered estimates.

A few notes on some of the supplements listed in the table:

Lane Labs describes AdvaCal Ultra 1000 as a “vegetarian capsule,” but it has vitamin D3, not vitamin D2. In addition to vitamin D, it has 1,000 mg calcium, 600 mg magnesium, and 122 mg “Other Bone Nutrients” (whatever that means). The result is a much larger pill that may be harder to swallow compared with a gel capsule of vitamin D.

Maximum D3 comes as capsules mounted on a push-out card of five “for convenience and safety in dosing.”

Perque D3 Cell Guard permits you to pour a drop at a time so you can pour it on food, on a spoon, or right into the mouth.

Vital Choice 1000 Vitamin D includes 1,000 mg of omega-3 wild salmon oil.

These preparations of vitamin D give you a pretty good idea of what’s on the market. Be careful not to pay too much — if you just want a vitamin D supplement, don’t go for the ones that put a bunch of other nutrients in the supplement.

Supplement dosage is usually given in international units (IU), but you may also see micrograms (mcg) or milligrams (mg). Table 13-3 shows the amount of vitamin D in international units, micrograms, and milligrams for the most common amounts.

Taking Vitamin D Supplements Correctly

Taking a vitamin D supplement correctly is easy. You simply need to have the right dose (usually in the form of a gel capsule), pop it into your mouth, and swallow it with a little water. That’s all there is to it. No advantage is gained to taking a supplement several times daily over taking one capsule once a day. But that vitamin D supplement is best absorbed when taken with food containing fat, and that’s the largest meal of the day for most people. Don’t take it on an empty stomach or in between meal times as you might with some medications.

A study at the Cleveland Clinic showed that if you take your vitamin D with the biggest meal each day, you can increase the level of vitamin D in the blood by an average of 50 percent.

Taking vitamin D once a day may be more reliable than taking seven times the dose once a week. You’ll probably remember it better on a daily basis. If you forget to take the pill one day, just take two the next day.

In the following sections, you find out about some of the drugs that may affect how your body absorbs vitamin D. I also give you a list of medical conditions that require higher doses of vitamin D.

Drugs that interfere with absorption

A number of drugs interfere with the absorption or metabolism of vitamin D. Among those that interfere with absorption are the following:

Antacids

Check with your doctor before taking vitamin D supplements if you have digestive problems. The problem may be more serious than just a lack of vitamin D.

Barbiturates

Carbamazepine

Cholestyramine

Colestipol

Fosphenytoin

H2 blockers: Tagamet, Pepcid, Axid, Zantac

Heparin

Highly Active Antiretroviral Therapy, a combination of three drugs for AIDS

Isoniazid

Mineral oil or products containing mineral oil

Orlistat

Phenobarbital

Phenytoin

Rifampin

St. John’s wort

Steroids such as prednisone and cortisol don’t prevent absorption of vitamin D, but they do affect the metabolism of vitamin D so that less active vitamin D is formed.

Medical conditions that increase your need for vitamin D

Several medical conditions increase your need for vitamin D:

Alcoholism

Intestinal diseases such as Crohn’s, celiac, cystic fibrosis

Kidney disease leading to failure

Liver disease

Overactivity of the parathyroid glands

Pancreatic disease

Surgical removal of the stomach

Surgical removal of the end of the small bowel (terminal ileum)

Because active vitamin D is formed after vitamin D passes through the liver and the kidneys, diseases of those organs affect the formation of active vitamin D. In that case, it may be necessary to give a form of vitamin D that doesn’t require the liver or the kidneys to intervene, either 25-hydroxyvitamin D if the liver is compromised, and calcitriol (active vitamin D) or 1-alpha-hydroxycholecalciferol (“1-alpha”) if the kidneys aren’t functioning correctly. However, these aren’t simple supplements — if you have liver or kidney problems, your doctor will prescribe these forms as part of your treatment regimen.

Determining a Supplement’s Effect on Blood Levels of Vitamin D

Occasionally someone may find that they are vitamin D–deficient. When this happens a question arises regarding how fast you can and should make up a deficit of vitamin D with supplements. Do you need a little, a few thousand units daily, or a very large dose every day?

If you need to get your level up rapidly to treat low serum calcium, for example, you will be prescribed 50,000 IU a week or 10,000 IU a day by your doctor; you’ll see improvement in both your calcium and your vitamin D levels in a week or two. After that your doctor will want you to take a regular vitamin D supplement with 600 to 1,000 IU vitamin D a day to make sure you don’t get deficient again.

If your vitamin D status is good but you simply want to get your vitamin D level up to a higher level like 30 ng/ml (75 nmol/L), you can just take a larger supplement (1,500 IU per day rather than 600 IU per day), and you’ll get to the new level within about two to three months. Of course in both cases you may want to get your 25-hydroxyvitamin D levels measured to verify you’ve reached your goal.

Be aware that if you’re taking vitamin D2 and the lab is using a method that only detects and reports 25-hydroxyvitamin D3, your efforts to raise your blood level will not be detected. Either take vitamin D3 to avoid this issue, or make sure that the test measures both vitamin D3 and vitamin D2.