Suplementing Vitamin D

A blood test measuring 25-hydroxyvitamin D levels can determine if you're deficient. Levels below 30 ng/mL are generally considered insufficient, with optimal levels typically between 40-60 ng/mL. People with limited sun exposure, darker skin, older adults, and those living in northern latitudes are at higher risk of deficiency.

The standard RDA is 600-800 IU daily, but many experts recommend 2000-5000 IU daily for optimal health, especially for those with deficiency. The safe upper limit is generally considered 4000 IU daily, though some people may need more under medical supervision.

Vitamin D3 (cholecalciferol) is the form produced in the skin from sunlight and is generally more effective at raising blood levels than D2 (ergocalciferol). D3 is derived from animal sources or lichen, while D2 comes from plant sources. Most supplements contain D3.

Yes, but it depends on factors like skin color, geographic location, time of year, and sun exposure duration. Fair-skinned people may need only 10-15 minutes of midday sun exposure several times per week, while those with darker skin may need longer exposure. However, many people struggle to get adequate sun exposure due to lifestyle factors.