For most of the last 20 years we have been talking to patients about maintaining healthy levels of vitamin D and avoiding deficiencies because of the widespread health ramifications. However more recently we've had a bit of a turnaround in that I have run into several cases of elevated vitamin D levels on blood samples that were in a concerning range. And based on the review of the most recent literature I'm not the only one raising a bit of an alarm.
First it's important to briefly remember your metrics: vitamin D levels below 30 are generally considered insufficient, and vitamin D levels above 80 considered unhealthy high. There is some debate in the medical and integrative space about the upper range, with some groups advocating healthy levels closer to 8 fo certain at-risk populations (autoimmune, active oncology), and the purpose of this blog is not to enter that debate (although my careful review of the issue seems to indicate that something more physiological that humans have experienced over the last 10,000 years based on sun exposure and skin manufacturing of vitamin D would be closer to 60 – 70 as an upper healthy range). But I would like to point out that there is a real risk of overdosing on vitamin D3 if you're taking several supplements at the same time, and not factoring the total vitamin D that may be found in all of them.
Many nutritional supplements sold both professionally and over-the-counter do contain some background level of vitamin D as a synergist, somewhere around 400 IUs on average. The original idea behind the supplementation was that the average person was not getting enough vitamin D and they would roll in a minimum level within a supplement to ensure results. This well-intentioned idea resulted in an unexpected problem over time, as more patients started self administering a variety of supplements for general health and stacking these 400 IU doses of vitamin D. For some of our patients, who are taking a regimen of prescribed supplements for specific goals, such as G.I. restoration, inflammation control etc., That amount could easily get above 10,000. More recently we had a patient whose routine blood level was above 200 (I didn't even think it was possible and had the patient get a second test to rule out or lab error). Looking at the supplementation that I was recommending the total amount she was taking was 6000 IUs, a dose that would never get her anywhere higher than 70 on her vitamin D serum levels. It was really her head scratching mystery for a while, until the patient started looking in her kitchen cabinet at some of the supplements she was taking most days, only to realize that a winter immune support and a hair and skin support she was taking on the side were both stacking over 10,000 IUs combined between those two alone.
The moral of the story: vitamin D supplementation is beneficial for most patients especially in our northern climates, but you have to remember to calculate your total intake. And it's also a great idea to get it measured once a year as part of your annual physical to make sure you're in the ballpark.