How much vitamin D should you take? That depends on you


As we head into cooler weather, it’s the ideal time to get your vitamin D tested – whether you live in the north like I do or a warmer climate too. 

You may not realize that even people who get adequate sunlight may become vitamin D deficient — with an impact on their bones.  That’s because vitamin D absorption and utilization differ, sometimes dramatically, from person to person.

Vitamin D needs vary greatly

Here are just a few interesting examples I’ve seen:

  • One woman in Connecticut had a vitamin D of level of 33 ng/mL in March — barely above the acceptable lower limit — despite taking 6600 IU of vitamin D during winter.  She increased her intake to 8600 IU for several months to reach the ideal 50 ng/mL level.
  • Another northeastern woman tested in August — when you’d expect her levels to be highest — was only 35 ng/mL despite taking 2000 IU of vitamin D daily year-round. She needed to add 2000 IU more to reach an optimal level. Contrast this to another client living in Denver, who had 53 ng/mL vitamin D in January when she was only taking 1000 IU daily.
  • And then there’s my own case — living in central New York, I was using 2800 units of vitamin D during the summer and getting lots of sunshine from my outdoor activities, but I still tested at 35 ng/mL in October.  If I had not raised my wintertime vitamin D intake substantially to 5,800 IU/day, I would’ve had a very inadequate level of vitamin D during the winter.

On average, vitamin D levels are expected to increase 10 ng/mL for every additional 1000 IU of vitamin D — but as you can see, the average doesn’t mean much in real-world situations! That’s why it’s crucial to get vitamin D testing to identify where you are starting — and retest a few weeks later to see if the amount you use is having an impact.

Why does the Vitamin D Council recommend 5000 IUs of vitamin D a day, 2013.
Boroń, D., Kamiński, A., Kotrych, D. et al. Polymorphisms of vitamin D3 receptor and its relation to mineral bone density in perimenopausal women. Osteoporos Int (2015) 26: 1045. doi:10.1007/s00198-014-2947-3
Hollis, B. W., Wagner, C. L., Howard, C. R., Ebeling, M., Shary, J. R., Smith, P. G., ... & Hulsey, T. C. (2015). Maternal versus infant vitamin D supplementation during lactation: a randomized controlled trial. Pediatrics,136(4), 625-634.
Drincic, Andjela T., et al. "Volumetric dilution, rather than sequestration best explains the low vitamin D status of obesity." Obesity 20.7 (2012): 1444-1448.
Mayo Clinic. Vitamin D toxicity rare in people who take supplements, researchers report. ScienceDaily, 30 April 2015.

  * Information presented here is not intended to cure, diagnose, prevent or treat any health concerns or condition, nor is it to serve as a substitute professional medical care.