Cholecalciferol vs. Ergocalciferol

What's the Difference?

Cholecalciferol and Ergocalciferol are two forms of vitamin D that are commonly used as dietary supplements. Cholecalciferol, also known as vitamin D3, is derived from animal sources such as fish oil or lanolin. It is the form of vitamin D that is naturally produced in the skin when exposed to sunlight. On the other hand, Ergocalciferol, also known as vitamin D2, is derived from plant sources like mushrooms or yeast. While both forms are converted into the active hormone in the body, cholecalciferol is considered to be more potent and has a longer half-life compared to ergocalciferol. Therefore, cholecalciferol is generally preferred for supplementation due to its higher bioavailability and effectiveness in raising vitamin D levels in the body.


Chemical FormulaC27H44OC28H44O
SynonymsVitamin D3Vitamin D2
SourceProduced in the skin when exposed to sunlightDerived from plants and fungi
Biological ActivityMore potent form of vitamin DLess potent form of vitamin D
MetabolismConverted to calcitriol in the liver and kidneysConverted to calcitriol in the liver
Food SourcesFatty fish, cod liver oil, egg yolksMushrooms, fortified foods
Supplement FormAvailable as D3 supplementsAvailable as D2 supplements

Further Detail


Vitamin D is an essential nutrient for maintaining healthy bones and teeth, supporting immune function, and regulating calcium and phosphorus levels in the body. There are two main forms of vitamin D: cholecalciferol (vitamin D3) and ergocalciferol (vitamin D2). While both forms are important for overall health, they differ in their sources, metabolism, and effectiveness. In this article, we will explore the attributes of cholecalciferol and ergocalciferol, shedding light on their similarities and differences.


Cholecalciferol is primarily synthesized in the skin when it is exposed to sunlight. Sunlight triggers a chemical reaction that converts 7-dehydrocholesterol, a compound present in the skin, into cholecalciferol. This form of vitamin D is also found in certain animal-based foods such as fatty fish, liver, and egg yolks. On the other hand, ergocalciferol is derived from plant-based sources. It is synthesized by irradiating a compound called ergosterol, which is found in fungi and yeast. Ergocalciferol is commonly added to fortified foods like milk and cereal products.


Once cholecalciferol or ergocalciferol is obtained through sunlight exposure or dietary intake, they undergo similar metabolic processes in the body. Both forms are first converted into their respective hydroxylated forms in the liver. Cholecalciferol is converted into 25-hydroxycholecalciferol (calcidiol), while ergocalciferol is converted into 25-hydroxyergocalciferol. These hydroxylated forms are then transported to the kidneys, where they undergo further hydroxylation to produce the active forms of vitamin D. Cholecalciferol is converted into 1,25-dihydroxycholecalciferol (calcitriol), the most potent form of vitamin D, while ergocalciferol is converted into 1,25-dihydroxyergocalciferol.


When it comes to effectiveness, cholecalciferol is considered to be more potent than ergocalciferol. This is because cholecalciferol is the natural form of vitamin D produced in the human body when exposed to sunlight. It has a higher affinity for the vitamin D receptor, allowing it to bind more effectively and exert its biological effects. On the other hand, ergocalciferol, being a synthetic form derived from plant sources, has a slightly lower affinity for the vitamin D receptor. However, both forms are still capable of raising blood levels of vitamin D and providing the necessary benefits.


Supplementation with cholecalciferol and ergocalciferol is commonly recommended for individuals with vitamin D deficiency or those who have limited sun exposure. Cholecalciferol supplements are widely available and often preferred due to their higher potency and similarity to the natural form of vitamin D produced in the body. Ergocalciferol supplements, on the other hand, are commonly prescribed for individuals with specific medical conditions or dietary restrictions. For example, individuals following a vegan or vegetarian diet may opt for ergocalciferol supplements as they are derived from plant sources.

Health Benefits

Both cholecalciferol and ergocalciferol offer numerous health benefits, primarily related to bone health and calcium regulation. Vitamin D plays a crucial role in the absorption of calcium and phosphorus from the intestines, ensuring their availability for bone mineralization. It also helps maintain adequate levels of these minerals in the blood, preventing conditions like osteoporosis and rickets. Additionally, vitamin D has been linked to immune system support, cardiovascular health, and even mental well-being. While the specific health benefits of cholecalciferol and ergocalciferol are similar, the potency of cholecalciferol may provide a slight advantage in terms of effectiveness.


In conclusion, cholecalciferol (vitamin D3) and ergocalciferol (vitamin D2) are two forms of vitamin D that play vital roles in maintaining overall health. While they differ in their sources and metabolism, both forms are capable of raising blood levels of vitamin D and providing the necessary benefits. Cholecalciferol, being the natural form produced in the body, is considered more potent and has a higher affinity for the vitamin D receptor. However, ergocalciferol supplements are commonly used in specific cases, such as dietary restrictions. Regardless of the form, ensuring adequate vitamin D intake is crucial for optimal health and well-being.

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