Vitamin D Supplements: What to Consider for Daily Use

Vitamin D supplementation is common, particularly among individuals with limited sun exposure or underlying health conditions. Be prepared to answer common questions patients may have.  

What is the difference between vitamin D2 and D3? Vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) are two forms of vitamin D. However, vitamin D2 is primarily plant-based, while vitamin D3 is often sourced from lanolin, a substance derived from animals. Although brief exposure to sunlight is the most efficient way to boost vitamin D levels, many people turn to food and supplements to meet their needs, and understanding these differences can guide supplement choice.

Which type of vitamin D is best? While both vitamin D2 and vitamin D3 can help improve vitamin D status, research shows that vitamin D3 is more potent and effective at raising those levels. For this reason, vitamin D3 is often the preferred recommendation among experts.

What is the right amount of Vitamin D? The recommended dietary allowance (RDA) varies by age: 600 IU (15 mcg) daily for people aged 1 to 70, including those who are pregnant or breastfeeding, and 800 IU (20 mcg) daily for people 71 years and older. Generally, tell patients not to exceed the daily upper limit of 4000 IU. However, in cases of vitamin D deficiency, higher doses may be needed under the guidance of a healthcare provider.

Are they safe? Vitamin D supplements are likely safe and generally well tolerated when used appropriately. However, high doses may lead to toxicity including elevated calcium levels, kidney problems, or even anemia. Toxicity usually occurs when vitamin D levels exceed 150 ng/mL.

For a more comprehensive analysis of the evidence, explore our vitamin D monograph.