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.
If you do not get enough Calcium in your diet, you need a Calcium Supplement. Calcium Carbonate can cause problems. Calcium Citrate is easier for most individuals to tolerate. It does not require much stomach acid to dissolve. It can be taken with meals or between meals. You can take Calcium Citrate if you take antacids or medicines for reflux disease. You should consider taking it if you are older (age 50 and above – like AARP).