Vitamin D — The Best Level
Hopefully by now you have spoken to your doctor, and gotten him or her to send you for a vitamin D level. Remember to make sure the lab order sheet says 25-hydroxyvitamin D or 25-OH D, and not 1,25.
So what should your vitamin 25-hydroxyvitamin D level be? As is often the case in medicine, there is no one easy one-size-fits-all answer here. Everyone's body is different. This is what makes the practice of medicine an art as well as a science. (And what makes medical training -- school followed by internship and residency training, go on and on.)
There are levels of vitamin D below which your body is deficient. That means kids will get rickets. There are levels that are adequate for bone health. And there are levels that we are discovering seem to be best for overall health, (not just our bones, but lungs, heart, immunity, etc.). We don't want vitamin D levels that are merely adequate. We want optimal.
To make matters even more complicated.....here is something to keep in mind and something you may not have considered before. How do you think we know the normal blood levels of all the things we check? The values that we use to determine whether your blood level of a particular substance is "normal" come from years of studying other people's blood. For instance, we know the range for a "normal" blood sugar level because we've studied the blood of many people who were healthy and "normal". Their blood sugar levels weren't exactly the same but they fell into a certain range. When other people were sick, and their blood sugar levels were found to be higher, (eg. diabetes), we determined that those levels were too high, and not normal. So, our knowledge of what blood levels are acceptable or healthy comes from studying a wide range of individuals. By knowing who the healthy ones are and what their blood levels are, we assume that other healthy people will have levels in that same range.
Of course, like I said before, medicine is very much an art as much as a science. Every now and then, someone healthy has a blood level of some substance that's out of the "normal" range. Maybe your blood sodium runs a little high or a little low, but you feel fine. Maybe you've been that way for years. Your doctor should know that. Your physician has to direct you and let you know whether or not you should be concerned. Often if it's the first time you have tested outside the norm, he or she will send you to be retested to make sure it isn't a lab error.
Now you know how we found those normal ranges you see on your lab reports. But what about vitamin D? Well, first let's look at how vitamin D blood levels are reported. Results can be in nanomoles per liter, (nmol/L), or nanograms per milliliter, (ng/mL). It makes a difference. The numbers will be very different, so look at your report, and see which of these your laboratory used. If you don't have the report, get a copy from your doctor, or directly from the lab.
Before we look at your numbers, consider this. A committee of the Institute of Medicine reviewed data on vitamin D needs. This is what they concluded:
- people are at risk of vitamin D deficiency if their 25-OH D levels are less than 30 nmol/L (less than 12 ng/mL)
- some people are at risk for inadequacy with levels in the 30 to 50 nmol/L (12 to 20 ng/mL) range
- for most people a level of 50 or more is sufficient
- there is a potential for harm with levels greater than 125 nmol/L (50 ng/mL)
Look at your report. It probably states that levels between 30 and 100 are in the normal range. That is also what many doctors will tell you. Some physicians will tell you that a level of 28 is okay, or not so bad. Others will accept a level of 31 or 32. But, pay attention to the Institute of Medicine report. Shoot for a level above 50 for optimal health. You will feel the difference.
Next.....how much vitamin D should you take to optimize your health?
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