Understanding Vitamin D4: What Are the Benefits of Taking It?

December 25, 2025 •

3 min read

While the vitamin D family contains multiple forms, the health benefits commonly discussed by nutritionists are not attributed to vitamin D4. This article clarifies the common misconceptions surrounding vitamin D4 and focuses on the proven benefits of the more recognized forms, D2 and D3.

Quick Summary

This article explores the truth about vitamin D4, a lesser-known form found in fungi, and addresses why there is no established list of health benefits for humans. It provides a detailed comparison with the well-researched vitamins D2 and D3, which are responsible for supporting bone density, immune function, and overall well-being.

Key Points

Vitamin D4 is not a common supplement: Unlike the well-known forms D2 and D3, vitamin D4 has no established role in human health.
Benefits are from D2 and D3: The health advantages associated with vitamin D, such as strong bones and immune support, are provided by ergocalciferol (D2) and cholecalciferol (D3).
Research on D4 is minimal: The effects and benefits of vitamin D4 in humans are not well-studied, and it is not a recommended supplement.
D3 is more potent than D2: Most evidence suggests that vitamin D3 is more effective than D2 at increasing and maintaining blood vitamin D levels.
Consult a professional: To ensure proper vitamin D intake and address any deficiency, it is best to speak with a healthcare provider, who can recommend the appropriate form and dosage of D2 or D3.

Demystifying the Vitamin D Family

Vitamin D is not a single compound but rather a group of fat-soluble secosteroids. While most people are familiar with vitamin D as the "sunshine vitamin," the family includes several different forms, known as vitamers. The most important and well-studied forms are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol), which are crucial for human health. Both D2 and D3 are absorbed from food and supplements and must undergo two hydroxylation steps in the liver and kidneys to become the biologically active hormone, calcitriol. This active form is what binds to receptors throughout the body to carry out its functions.

The Role and Research of Vitamin D4

Vitamin D4, also known as 22-dihydroergocalciferol, is a distinct compound within the vitamin D family that is produced by fungi, including certain species of mushrooms. Unlike vitamin D2 and D3, vitamin D4 is not a common dietary component and has not been widely studied for its effects in humans. Most scientific and medical literature does not cite proven health benefits associated with the consumption of vitamin D4.

There is limited laboratory research on vitamin D4, primarily in cellular models, suggesting it might have some biological activity, but its bioavailability and efficacy in humans remain unknown. A study published in the journal Applied Biological Chemistry mentioned that vitamin D4 showed similar cellular uptake to D2 and D3 in intestinal cell models, but this does not confirm human benefits. Any discussion of the benefits of vitamin D almost exclusively pertains to D2 and D3, not D4.

The Established Benefits of Vitamins D2 and D3

When people search for the benefits of vitamin D, they are seeking information on the well-researched functions of vitamins D2 and D3. These include:

Bone Health: Vitamin D is critical for the intestinal absorption of calcium and phosphorus, two minerals essential for building and maintaining strong bones. A deficiency can lead to bone-softening diseases like rickets in children and osteomalacia in adults.
Immune System Modulation: It helps the immune system fight off invading bacteria and viruses. Low levels of vitamin D are linked to a higher risk of respiratory infections.
Muscle Function: Vitamin D is necessary for muscle movement and development. Chronic deficiency can cause muscle weakness and cramps.
Brain Health: It is important for proper brain function and may offer protective benefits against cognitive decline. Research suggests low levels may be linked to an increased risk of depression, though supplementation has shown mixed results.
Reduced Inflammation: The active form of vitamin D helps to reduce inflammation throughout the body.

Choosing the Right Supplement: D2 vs. D3

While both ergocalciferol (D2) and cholecalciferol (D3) effectively increase vitamin D levels, studies show that vitamin D3 is generally more potent and may raise blood levels higher and for a longer duration than D2. For this reason, vitamin D3 is often the preferred form for supplementation, though D2 remains an effective option, especially for those on vegan diets, as it is plant-derived.

Vitamin D Form Comparison


Feature	Vitamin D2 (Ergocalciferol)	Vitamin D3 (Cholecalciferol)	Vitamin D4 (22-Dihydroergocalciferol)
Primary Source	Plants and UV-irradiated fungi	Animal products (e.g., fatty fish, eggs), sunlight on skin	UV-irradiated fungi (certain species)
Effectiveness	Effective for raising vitamin D levels	Generally more effective at raising and sustaining blood levels	Efficacy in humans is unknown and not studied for supplementation
Common Use	Supplementation, often prescription-strength	Supplementation, over-the-counter, and fortification	Not used as a human supplement
Status	Common and well-researched	Most common and best-researched for humans	Rare, not a standard supplement

Conclusion: Focus on D2 and D3, Not D4

To conclude, while vitamin D4 exists as a chemical compound found in certain fungi, it is crucial to understand that it is not the source of the well-documented health benefits associated with vitamin D. The benefits for bone health, immune function, and overall well-being are provided by vitamins D2 and D3. As D4 is not a standard dietary supplement and its effects in humans are largely unstudied, any claims regarding its benefits should be treated with skepticism. For reliable vitamin D support, consumers should seek supplements or food sources of D2 or, preferably, D3, and consult a healthcare professional to determine their needs. This approach ensures you are receiving the established benefits of this essential nutrient.

For more detailed information on vitamin D, consult the National Institutes of Health's Office of Dietary Supplements at ods.od.nih.gov.

Frequently Asked Questions

Vitamin D4, or 22-dihydroergocalciferol, is a form of vitamin D produced in certain fungi after exposure to ultraviolet light. It is a lesser-known vitamer and is not a standard human dietary supplement.

No, there are no established or proven health benefits of taking vitamin D4 in humans. Most scientific research on vitamin D and its benefits focuses on the more common forms, D2 and D3.

The two main forms of vitamin D relevant to human health are vitamin D2 (ergocalciferol), found in plants and fungi, and vitamin D3 (cholecalciferol), which is produced in the skin from sun exposure and found in animal products and some plant-based sources like lichen.

Because vitamin D4 has not been adequately researched in humans, its safety and efficacy as a supplement are unknown. It is not recommended for consumption and is not commercially available for that purpose.

For optimal vitamin D status, you should focus on sun exposure (when safe), eating foods rich in vitamin D2 or D3, and taking D2 or D3 supplements if your doctor recommends it. Supplementation with D3 is often preferred due to higher potency.

Vitamin D4 is a rare form primarily found in certain fungi, such as mushrooms, that have been exposed to ultraviolet light. It is not available as a commercial supplement for human use.

No, you will not find vitamin D4 supplements on the market. Health supplements are based on the well-researched forms D2 and D3, which have established benefits for human health.