Older children, teenagers, and adults need much more than the 400 IU of Vitamin D that is “100%” listed on a multiple vitamin bottle. Panel members at the 2010 National Osteoporosis Foundation meeting recommended 1400 to 3000 IU of Vitamin D daily for teenagers and adults. Individuals vary in their needs. I recommend 2000 IU of Vitamin D daily as a good first estimate of daily need.
The only way to be certain of your personal need is to Test for Vitamin D Level. This is a blood test that is rarely ordered except by osteoporosis specialists. Once you know your Vitamin D level, you can judge how adequate your long term intake of vitamin D has been. Then you can adjust your intake accordingly Vitamin D is a stored vitamin. Therefore, if you have a long term Vitamin D Deficiency, you need to fill up your storage areas before you will use (not store) your entire daily intake.
If you are really low, this will take months or even years at just 2000 IU daily. We use 50,000 IU of D3 taken 3 times weekly to recover quickly from serious deficiency. Total dose varies by a person’s size and degree of deficiency. We occasionally need to use over 2,000,000 IU.
Jay Ginther, MD
2008 / Revised January 2011