IU stands for international units and is a way to measure the biological activity of certain substances, including fat-soluble vitamins. It indicates how much of a vitamin is needed to produce a specific effect in the body.
For example, the recommended daily intake of vitamin D for children up to 12 months old is 400 IU. This means that a child needs 400 IU of vitamin D each day to maintain healthy bone growth.
Here's a breakdown of what IU measures:
- Fat-soluble vitamins: IU is typically used to measure the four fat-soluble vitamins: vitamin A, D, E, and K.
- Biological activity: IU doesn't measure the weight or volume of a vitamin but rather its biological activity, or potency, in the body.
- Varying measurements: The IU measurement can vary depending on the biological activity of the substance per unit of mass or volume.
Therefore, IU is a helpful unit for measuring vitamin intake and understanding how much of a particular vitamin is needed to achieve a specific health benefit.
