Vitamin D is having a moment. Actually, it's been having a moment for quite a while now. As such, questions are emerging, as they tend to do with "medical miracle" darlings. One question I hear keeps coming up is about the appropriate dosing of vitamin D. Should everyone be taking it and, if so, at what dose?
There have been reams of research coming out over the past several years about the potential health harms of vitamin D deficiency, as well as the potential health benefits of vitamin D supplementation. We also know that vitamin D deficiency is pretty common - more so for certain people.
According to a 2011 report from the Centers for Disease Control and Prevention, while the majority of Americans have sufficient levels of vitamin D, a quarter are at risk of vitamin D inadequacy (defined as a serum 25OHD level of 30 to 45 nmol/L) and nearly ten percent are at risk of vitamin D deficiency (defined as a serum 23OHD level less than 30 nmol/L). The risk varies according to age, sex, race and ethnicity with higher prevalence in older people and women, and lower prevalence for non-Hispanic white people. In women, the prevalence is lower in pregnant and lactating women.
We know that vitamin D is important, we need it, and that some people may not have enough of it. But perhaps the first question to be asked is not what dose I should be taking but, rather, do I need to take it at all? You know that we make vitamin D ourselves - no supplement required. We are equipped with the physiological capability to manufacture vitamin D via sun exposure. The hitch is that sun exposure is also getting its share of press, in terms of the negative consequences of too much exposure leading to premature aging and, potentially, skin cancer. The other issue here is that some people are "better" at manufacturing vitamin D than others.
So once we've decided that vitamin D supplementation is in fact appropriate, the next logical question may then be:
How much vitamin D is too much?
A recent question came my way on the dose of 50,000 IU weekly. Too much? According to the National Institutes of Health Office of Dietary Supplements, there is risk related to extended use of high doses of vitamin D (and 50,000 IU of Vitamin D weekly qualifies as high dose). High doses can lead to toxicity; symptoms can include excessive urination, GI upset, and irregular heartbeat. Vitamin D toxicity can also raise levels of calcium in the blood - this can lead to damage to the heart, blood vessels, and kidneys. Long term use of very high doses increases the risk of toxicity.
But that being said, there are also many potential benefits of vitamin D, as stated earlier. As it is with most medical questions, one should discuss concerns with his/her doctor, remembering that each individual requires individual care. There is not, never was, and likely will never be, any one size fits all - vitamin D dosing included.
Published On: June 16, 2014