What Is The Difference Between Vitamin D And Vitamin D3?

Quick Health Scoop

• You can get vitamin D from three main sources: the sun, food, and dietary supplements
• Vitamin D contains both vitamin D2 (found in plants) and vitamin D3 (produced in the body and also found in animal foods)
• Research shows that vitamin D3 (cholecalciferol) increases blood levels of the vitamin better than vitamin D2 (ergocalciferol) ^[9]
• Because you might get a limited amount of vitamin D from sun exposure and from food, consider vitamin D supplementation to fill in any nutritional gaps

Vitamin D vs D3, what’s the difference? Well, did you know that vitamin D actually comes in two different forms: vitamin D2 and D3? Crucial to your health and well-being, vitamin D delivers a host of benefits to keep your body functioning properly. Most notably, this fat-soluble vitamin supports strong, healthy bones by working in tandem with calcium, one of the primary minerals in bone. How? Vitamin D is needed for your body to absorb calcium.1 But vitamin D also supports muscle function, muscle strength, balance, and immune health.^[2,3]†

Given the critical roles vitamin D plays in your body’s healthy growth and functioning, does it matter “which” vitamin D you get? What is the difference between vitamin D and vitamin D3? And how does vitamin D2 fit into the mix? Let’s dig into what the research says.

Learn More: What Vitamins Do I Need?

Is Vitamin D3 the Same As Vitamin D?

First, it helps to know where vitamin D (a.k.a. The Sunshine Vitamin) comes from. You can get this key nutrient from three main sources: the sun, food, and vitamin D supplements. But which form of vitamin D is present in these three sources of vitamin D?

Is there a difference between vitamin D and vitamin D3? Technically, vitamin D describes both vitamin D2 and vitamin D3, which differ in a few ways but function similarly in the body. Think of vitamin D as the “umbrella term” for a nutrient that comes in several different forms, similar to the B family of vitamins that includes thiamin, riboflavin, niacin, folic acid, and others.

The nutrient form Vitamin D2, or ergocalciferol, is made from plants and is added to some foods and supplements to fortify them with vitamin D.^[5] Sources of vitamin D2 include mushrooms (grown in UV light, which boosts vitamin D2 levels), fortified foods (such as milk, breakfast cereals, and orange juice), and some dietary supplements.

The human body naturally produces Vitamin D3 (cholecalciferol) when you expose your skin to the sun, however for vitamin D to be produced in the skin to its active form, face arms and legs need to be exposed to direct sunlight without sunscreen for at least 5 to 15 minutes a day. Vitamin D3 is also found in a few animal foods and dietary supplements.^[5,6] Sources of vitamin D3 include fatty fish (think mackerel, salmon, trout, and tuna), fish liver oils, beef liver, and egg yolks.

Once you get vitamin D (either through sun exposure, food, or vitamin D supplements), the body stores it in fat cells, where it stays inactive until needed. Next, the “hydroxylation process” kicks in, where the kidneys and liver transform the stored vitamin D into the active vitamin D—the form the body can use (known as calcitriol).^[6] If your body has low vitamin D levels, it can only absorb 10% to 15% of dietary calcium, but with normal vitamin D levels, your body’s calcium absorption soars to 30% to 40%.^[7]

If you’re wondering why foods are fortified in the first place, it stems back to the 1930s, when rickets was rampant. Rickets—a disease that softens and weakens bones—stems from symptoms of vitamin D deficiency.^‡†[8] Even though the prevalence of Rickets in the U.S. is now rare, nearly all of our country’s milk supply is fortified, with each one-cup serving containing about 3 mcg (120 IU) of vitamin D. Many plant-based milk alternatives (like almond and soy milk) are similarly fortified with vitamin D2 and/or vitamin D3, as are cereal and some orange juices. ^[2,6]

What Affects Natural Vitamin D Production from Sunlight?

Vitamin D3 is the form your body produces when exposed to sunlight, but how much you make can vary widely. Here are some factors that influence how efficiently your skin synthesizes vitamin D:^[9]

• Time of day: Midday sun (10 a.m. to 2 p.m.) offers the most UVB rays needed for vitamin D production.
• Season: In winter or in northern latitudes, UVB rays may not be strong enough to trigger vitamin D synthesis.
• Geography: The farther you live from the equator, the lower your year-round UVB exposure.
• Skin coverage: Clothing, hats, and sunscreen can block UVB rays, reducing vitamin D production.
• Skin tone: Individuals with deeper skin tones may require more sun exposure to produce the same amount of vitamin D as those with lighter skin.

What Is The Best Form Of Vitamin D To Take?

In generally healthy people, the daily amount of vitamin D needed (measured in international units) depends on age, with recommended dosages below:^[12]

However, if you’ve got a vitamin D deficiency^‡, which can be easily diagnosed by your healthcare provider from a simple blood test, you’ll probably need more than that—at least temporarily—until your blood test shows you have optimal vitamin D levels. Your healthcare provider will be able to help determine which vitamin D3 supplement will fit your needs.^†

The Bottom Line

Vitamin D plays a critical role in your well-being by supporting bone health, maintaining healthy immune function, and other key functions. You can obtain this vital nutrient from three main sources: the sun, food, and supplements. Vitamin D vs. D3, what’s the difference? Technically, vitamin D relates to both vitamin D2 (which comes from plants) and vitamin D3 (which the body produces naturally and also comes from animal foods). However, both forms function similarly in the body. Research shows that vitamin D2 is less effective than vitamin D3 at raising blood levels of vitamin D. If you're the indoorsy type and get less than 15 minutes of sun exposure every day, have darker skin, or if you've been diagnosed with vitamin D insufficiency or a vitamin D deficiency^‡, then you may want to consider vitamin D3 supplementation, as it’s an easy way to increase your vitamin D intake. Check with your healthcare provider about your vitamin D status so they can help determine which supplemental vitamin D product is right for you.^†

Continue to check back on the Nature Made blog for the latest science-backed articles to help you take ownership of your health.

Learn More About Vitamins & Supplements:

• Biotin vs Collagen: What's the Difference?
• What’s the Difference Between Omega 3 vs 6 & 9?
• Folate Vs. Folic Acid: Are They the Same Thing?

This information is for educational purposes only and is not intended to serve as medical advice or a recommendation for any specific product. Consult your health care provider for more information.

References

1. Mayo Clinic. Vitamin D. Mayo Clinic. Published March 21, 2025. https://www.mayoclinic.org/drugs-supplements-vitamin-d/art-20363792 
2. National Institutes of Health. Vitamin D. National Institutes of Health. Published November 8, 2022. https://ods.od.nih.gov/factsheets/VitaminD-Consumer/ 
3. Aranow C. Vitamin D and the immune system. J Investig Med. 2011;59(6):881-886. doi:10.2310/JIM.0b013e31821b8755
4. National Institutes of Health. Vitamin D. National Institutes of Health. Published 2025. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
5. Harvard T.H. Chan School of Public Health. “Vitamin D.” 2021. Accessed on: September 23, 2025. https://www.hsph.harvard.edu/nutritionsource/vitamin-d/
6. Moriarty C. Vitamin D Myths “D”-bunked. Yale Medicine. Published March 15, 2018. https://www.yalemedicine.org/news/vitamin-d-myths-debunked
7. Harvard Health Publishing. Vitamin D and your health: Breaking old rules, raising new hopes - Harvard Health. Harvard Health. Published May 17, 2019. https://www.health.harvard.edu/staying-healthy/vitamin-d-and-your-health-breaking-old-rules-raising-new-hopes
8. Dietary Reference Intake: Guiding Principles for Nutrition Labeling and Fortification. “Overview of Food Fortification in the United States and Canada.” 2003. Accessed: September 23, 2025. https://www.ncbi.nlm.nih.gov/books/NBK208880/
9. Kift RC, Webb AR. Globally Estimated UVB Exposure Times Required to Maintain Sufficiency in Vitamin D Levels. Nutrients. 2024; 16(10):1489. https://doi.org/10.3390/nu16101489
10. Heaney RP, Recker RR, Grote J, Horst RL, Armas LA. Vitamin D(3) is more potent than vitamin D(2) in humans. J Clin Endocrinol Metab. 2011;96(3):E447-E452. doi:10.1210/jc.2010-2230
11. Reider CA, Chung RY, Devarshi PP, Grant RW, Hazels Mitmesser S. Inadequacy of Immune Health Nutrients: Intakes in US Adults, the 2005-2016 NHANES. Nutrients. 2020;12(6):1735. Published 2020 Jun 10. doi:10.3390/nu120617354.
12. The Journal of Clinical Endocrinology & Metabolism, Volume 96, Issue 7, “Evaluation, Treatment, and Prevention of Vitamin D Deficiency: an Endocrine Society Clinical Practice Guideline.” 1 July 2011, Pages 1911–1930, https://doi.org/10.1210/jc.2011-0385

‡ Approx. 29% of the U.S. adults are Vitamin D deficient (<50 nmol/L) (Source: Endocrine Society, NHANES)