The excitement over the health benefits of vitamin D have, not unexpectedly, generated lots and lots of questions about how, why, and when to best use it.
Let's review some of the most frequent questions and answers about vitamin D.
Now, please keep in mind that much of this is my opinion, based on clinical experience replacing vitamin D in over 1000 patients. I've learned a lot of lessons along the way, and I'm still learning new lessons and making new observations. But this is the approach I have applied successfully and safely. (Please, always consult your doctor to discuss your unique health situation.)
My starting level of vitamin D was 19.4 ng/ml. I took 6000 units of vitamin D (yes, a gelcap) and my level increased to 59.8 ng/ml. My doctor then said it was okay to stop it.Do you agree with stopping vitamin D?
No. I absolutely do not agree with stopping your vitamin D, unless of course you have reason to believe you will be obtaining vitamin D from substantial sun exposure. But, if not, it is clear that once you stop supplementing vitamin D, your blood level will drift right back down to the prior level, since your body is not making it.
_How often should vitamin D blood levels be checked? _
There are no hard and fast rules to go by, but I have found every 6 months to work well. Ideally, the two blood levels are in mid-summer and mid-winter, giving you and your doctor an idea of the fluctuations of your vitamin D level. Contrary to what you hear in the media, I find that the majority of adults, particularly those over 40 years old, fail to activate much vitamin D on sun exposure. Most adults do not raise their blood level much more than 10-15 ng/ml even with summer sun exposure. However, there are occasional exceptions. That's why it's important to know your individual level of fluctuation.
_I'm 56 years old and I like to get a tan in summer and occasionally use a tanning parlor in the winter months. Though my doctor is not wild about the tanning, he said that it was not necessary to check my blood level of vitamin D and I shouldn't add any additional vitamin D. Does that sound correct? _
I disagree with this advice. A tan does not equal vitamin D activation, particularly as we age. I have had many patients with dark Caribbean tans from extended vacations have blood levels of vitamin D clearly in the deficient range, occasionally <20 ng/ml.
The only confident way to know your vitamin D level, tan or no, is to check a blood level.
_My doctor said that vitamin D might interfere with my cholesterol drug and other medications. Why is that? _
Well, for the vast majority, it's not true.
With rare exceptions, taking vitamin D is no more likely to interfere with medications than getting a tan (should you retain the ability to activate vitamin D). The only exceptions that I am aware of would be thyroid medication, which shouldn't be taken at the very same time as vitamin D; the old-fashioned cholesterol drug, cholestyramine, can prevent vitamin D from being absorbed, as can weight-loss fat-blocker, Xenical ®, or its over-the-counter equivalent, Alli ®. Rarely, thiazide diuretics can raise blood calcium and vitamin D can exaggerate this effect. (This may be a reason to have an occasional calcium level checked by your doctor.) There are also special issues if you are receiving treatment for cancer or have cancer; however, since some of the most exciting new developments for vitamin D have been in the world of cancer prevention and treatment, this is worth a serious conversation with your doctor or oncologist.
All in all, the vast majority of people can take vitamin D without worry about interactions with drugs. Of course, there are always peculiar or unique situations that should always be discussed with your doctor, who should know your health situation best.
_We live in Florida. My husband and I spend much of our day outdoors, since we are both retired. _
_I figure that our outdoor lifestyle means that we probably don't need to take vitamin D. Do you agree? _
No, I do not agree. Since you and your husband are retired, I assume that you are somewhere in your 60s or older. This means that much of the capacity for activation of vitamin D in your skin has been lost.
An informative 2005 study performed in Miami residents over age 65 showed that blood levels of vitamin D were clearly deficient during winter, with blood levels ranging around 25 ng/ml. But they were little better in summer, ranging from 25 ng/ml in women to 31 ng/ml in men (mean values). On average, both men and women raised blood vitamin D a meager 14% from summer to winter. Obviously, it's probably somewhat worse the farther north we go.
Therefore, by not checking and supplementing vitamin D, it is highly likely that you and your husband are deficient year round, even in Florida, despite sun exposure.
The message: Get vitamin D checked, but don't be surprised if your level is low; it's the rule, rather than the exception.
_I take fish oil capsules for heart health. This means I don't have to take vitamin D, right? _
Nope, sorry. Fish oil is fish oil containing omega-3 fatty acids, EPA and DHA; vitamin D is vitamin D.
Perhaps the confusion arises from the fact that cod liver oil contains both omega-3 fatty acids and vitamin D. Much vitamin D is also made from fish oil, but the two components are separated to yield fish oil without vitamin D, and vitamin D without omega-3 fatty acids. Both exert their own independent benefits. In my view, both are best taken separately.
_Why not just take cod liver oil and get both omega-3 fatty acids and vitamin D at the same time? _
Some people do indeed choose this route. However, it's not my first choice since I find it difficult to change the dose of omega-3 fatty acids or vitamin D independently, not to mention that vitamin A is also present. Because the doses of vitamin D I advocate in my patients often ranges in the 4000-10,000 units per day, occasionally higher, this would lead to taking excessive, potentially toxic levels of vitamin A from a cod liver oil preparation.
_Is it possible to take too much vitamin D? _
Yes, indeed it is.
Vitamin D toxicity is evidenced by a rise in blood calcium to the abnormally high range, but it is rare if you and your doctor are monitoring blood levels of vitamin D. Vitamin D authorities differ to some degree on what level of vitamin D in the blood could begin to account for toxic effects, with some proposing that levels as low as 80 ng/ml, while others propose as high as 150 ng/ml.
I aim for blood levels of 60-70 ng/ml in my patients. In 1000 patients, I have not uncovered a single episode of increased calcium caused by vitamin D. Nonetheless, the safest way to proceed is to always check a blood level of vitamin D. I add a blood calcium when there are unusual circumstances in a patient's situation, such as a history of high calcium, a history of hyperparathyroidism, kidney disease, thiazide diuretics, sarcoidosis, and some other rare situations.
But, all in all, vitamin D is an amazingly empowering, health-restoring or -maintaining strategy, and toxicity is an unusual occurrence. Don't be afraid of vitamin D; just be aware of some of the special issues that surround its safe use.