Vitamin D3 (cholecalciferol) is the form your skin makes from sunlight. It raises active vitamin D levels in the blood more efficiently than the D2 form. This vitamin helps the body absorb calcium and supports immune function, bone maintenance, and mood regulation.
Many people reach for D3 to maintain healthy bones and support immunity, especially when sun exposure is low. It is also used to bolster mood and energy during darker winter months.
Take D3 with a meal or snack that contains some fat. Without fat absorption drops because the vitamin is fat-soluble. Morning dosing, often with the largest meal of the day, is common.
Because D3 is fat-soluble, it can accumulate. Extended high-dose use may push calcium levels too high.