Vitamin D2 vs. D3: Benefits, Differences, Sources

The differences between vitamins D2 and D3 include that D2 is plant-based and D3 comes from animal products and sunlight. D3 often increases vitamin D levels more effectively.

Vitamin D is known to support bone health. Vitamins D2 and D3 help the body absorb calcium and phosphorus, which are essential for building and maintaining strong bones.

Without enough vitamin D, bones can become brittle, thin and soft, increasing the risk of fractures and diseases like osteoporosis. In children, prolonged and severe vitamin D deficiency can lead to rickets, a condition that causes soft bones, stunted growth, and pain.

Vitamins D2 and D3 also play an important role in immune function, muscle strength, and the regulation and function of the nervous system.

Vitamins D2 and D3 are types of vitamin D that help maintain or increase vitamin D levels in the blood and treat deficiencies. They have slightly different chemical structures and come from different sources.

Where they are trained

Vitamin D2 (ergocalciferol) is primarily produced when ergosterol, a compound found in plants and fungi, is exposed to sunlight or ultraviolet (UV) light.

Vitamin D3, for its part, is mainly produced by the body when the skin is exposed to the sun. This happens when UVB rays from the sun convert a substance in the skin called 7-dehydrocholesterol into vitamin D3 through a series of chemical reactions. You can also find vitamin D3 in animal products like oily fish, egg yolks and cheese.

How they are processed in the body

Vitamins D2 and D3 are both well absorbed in the small intestine, but they are broken down slightly differently in the liver.

When vitamin D2 is consumed, the liver converts it to 25-hydroxyvitamin D2 (ercalcidiol), while vitamin D3 is transformed into 25-hydroxyvitamin D3 (calcidiol). Together, these compounds are known as calcidiol, the main circulating form of vitamin D and what health care providers typically measure when testing vitamin D levels.

Calcidiol is then converted to calcitriol, the fully active form of vitamin D that the body can use, in the kidneys.

Vitamin D3 might be more effective in boosting vitamin D levels

Research shows that vitamin D3 may be more effective than vitamin D2 in increasing levels of vitamin D circulating in the blood. A recent review of 24 studies found that on average, people taking vitamin D3 had vitamin D levels 15.69 nanomoles per liter higher than those taking vitamin D2.

Research also shows that vitamin D3 supplements can help maintain higher vitamin D levels for a longer period of time than vitamin D2.

The processing of vitamins D2 and D3 in the body can vary from person to person depending on age, gender and ethnicity. Although studies indicate that vitamin D3 may be more effective than vitamin D2, more research is needed to definitively determine this.

The recommended daily intake of vitamin D includes all sources of vitamin D and varies by age. It is usually measured in international units (IU) or micrograms (mcg), and doses are not broken down by type of vitamin D. The recommended daily amount of vitamin D is: