I take a pill that [contains] 600 mg Calcium and 400 IU vitamin D.
I'm a 26 year old female. Is this a good decision?
Via the blog
If you find that your diet does not provide sufficient calcium, then supplementing it is certainly a good decision. Having Vitamin D in the same pill as calcium is particularly smart, as this helps facilitate absorption. However, 600 milligrams is too much for the body to absorb at once. I recommend a supplement containing no more than 500 milligrams. Also, be sure to check your supplement’s bottle for the amount of “elemental calcium” – this tells you how much of the calcium in the supplement is “up for grabs.”
Some not-so-trustworthy companies advertise themselves as offering large amounts, but read the fine print and you'll see that each pill doesn't offer that much absorbable calcium.