Tag: Supplemental vitamin d

According to the National Institutes of Health (NIH), the tolerable upper intake level (UL) for vitamin D is 4,000 international units (IU) per day for most adults. However, this upper limit does not mean the dose is appropriate for everyone, and recent research has explored potential risks associated with this intake level.

The primary circulating form of vitamin D, 25-hydroxyvitamin D (calcidiol), has a half-life in the bloodstream of approximately 15 days. For a 5000 IU dose, the vitamin D itself is rapidly cleared from the blood within days, but the body stores a significant portion in fat cells, releasing it slowly over weeks or even months. This means a single high dose can have a prolonged effect on your vitamin D levels, a feature that depends heavily on individual factors.