There is a big push for Vitamin D this winter. We're hearing about it on TV and in all of the women's mags. Not only is it supposed to be good for bone strength and bone density, but it's supposed to give a big boost to your immune system. These sources are recommending 1000IU per day, but that depends on how much you already get from other sources. For example, our pediatrician said 1000IU was too much for my teen, and my husband works outside, so he gets a ton from the sun and too much can be toxic. It also depends on what other meds you are taking so be sure and always check with your doctor before putting yourself on a supplement.