 [ Symptoms ] what is the recommended daily dosage of vitamin d3 for women [ Disease ] vitamin d3 is often the form of vitamin d that you will see in vitamins and supplements the answer to this question depends on your age women 70 and under need 600 iu of vitamin d a day women 71 and over need 800 iu to help support strong bones older people need more vitamin d because their skin does not create vitamin d as efficiently when exposed to the sun their kidneys are also not as effective at producing the active form of vitamin d vitamin d is critical for strong bones as it helps your body absorb calcium you will often see calcium and vitamin d combined in the same supplement so it is important to get enough of both of those nutrients