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) 
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 vitamin 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.
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 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.
In foods and supplements, vitamin D comes in two primary forms (below) that differ chemically only in their structures and are well absorbed in the small intestine.
Vitamin D2 (ergocalciferol). This nutrient form is made from plants and is added to some foods and supplements to fortify them with vitamin D. 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.
Vitamin D3 (cholecalciferol). The human body naturally produces this nutrient 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. 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 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). 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%.
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 vitamin D deficiency.‡ 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 Is The Best Form Of Vitamin D To Take?
Vitamin D vs D3 vs D2? Research shows that vitamin D3 is roughly 87% more potent in raising blood levels of vitamin D and produces two to three times greater storage of vitamin D in the body compared to vitamin D2, thus making vitamin D3 the preferred vitamin D deficiency solution‡.
Keep in mind two important issues with the different sources of vitamin D.
Sun. While spending 10-15 minutes in the sun every day (without sunscreen, exposing your face, legs, and arms) can increase your vitamin D intake, you might be worried about damaging UV rays. You face an increased risk of developing skin cancer when you spend extended time in the sun without skin protection (i.e., sunscreen, clothing, hats, and sunglasses).
Food. Very few foods naturally contain vitamin D, with the best sources being the flesh of oily fish. Because most people don’t consume large enough quantities of vitamin-D rich foods, they can’t be the sole source of vitamin D for many.
Due to the issues cited above, you might get a limited amount of vitamin D from sun exposure and from food (including fortified food). While it’s extremely important to add vitamin-D rich foods to your diet, you should also consider takinga vitamin D supplement in the form of vitamin D3. Nature Made offers a variety of vitamin D3 supplements to choose from.
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.
Dietary Reference Intake: Guiding Principles for Nutrition Labeling and Fortification. “Overview of Food Fortification in the United States and Canada.” 2003. Accessed: October 5, 2021. https://www.ncbi.nlm.nih.gov/books/NBK208880/
The Journal of Clinical Endocrinology and Metabolism. “Vitamin D(3) is more potent than vitamin D(2) in humans.” December 22, 2010. Accessed on: September 6, 2021. https://pubmed.ncbi.nlm.nih.gov/21177785/
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
As a member of the Medical and Scientific Communications team, Sandra educates healthcare professionals and consumers on nutrition, supplements, and related health concerns. Prior to joining Pharmavite, Sandra worked as a clinical dietitian at University of Chicago Medicine in the inpatient and outpatient settings. Sandra received her Bachelor of Science degree in Nutritional Science, with minors in Spanish and Chemistry from the University of Arizona in Tucson, AZ. She earned her Master of Science degree in Clinical Nutrition from RUSH University in Chicago, IL. As part of her Master’s program, Sandra performed research on physical activity participation and correlates in urban Hispanic women.
Lisa Beach is a seasoned journalist whose work has been published in The New York Times, Good Housekeeping, Eating Well, Parents, AARP’s Disrupt Aging, Optimum Wellness, and dozens more. She also writes for a variety of health/wellness-focused brands. Check out her writer’s website at www.LisaBeachWrites.com.