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What’s the Difference Between Vitamin D, D2, and D3?

Are there really three separate types of vitamin D? Is one better than the others? Find out here!

By Stephen C. George; Medically Reviewed by Dr. Ahmad Talha Azam
Feb 28, 2024 2:50 PMApr 4, 2024 7:22 PM
Portrait of Asian lovely girl drinking milk from glass on a white background
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We all know that vitamin D is a necessary nutrient for good health. The vitamin is important in helping your system absorb the calcium it needs to maintain strong and healthy bones. We also need vitamin D to support various other functions and systems in the body.

But if you’ve been shopping the supplement aisle, you must have noticed that there isn’t just one form of vitamin D: vitamin D2 and D3 are called out on various labels, too. What exactly is the difference between D, D2, and D3? Are they all forms of the same vitamin, or is each one a completely different nutrient altogether? What foods can you find them in? Is any one of these better for you than the others? We’ve got the lowdown on the different types of vitamin D right here.

What Is Vitamin D?

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Also known as calciferol, vitamin D can be found naturally in some foods. It’s also added to a lot of processed foods (making them fortified with vitamin D) and of course is available in many supplement forms, typically pills.

Vitamin D enables your body to absorb calcium from your diet (either from the foods you eat, or from other supplements). It also helps you absorb phosphorus, another critical mineral that your body needs for strong teeth and bones, as well as helping with tissue and cell repair. Vitamin D is available in two main forms — D2 and D3.

What Is Vitamin D2?

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Unlike some other vitamins that are assigned various numbers to denote that they are different nutrients, vitamins D2 and D3 are practically the same nutrient — both are types of calciferol — with just a few differences that are worth pointing out.

D2, also known as ergocalciferol, comes from plant and fungus sources. It’s mainly produced by artificially exposing mushrooms or yeast to ultraviolet light, with the resulting product used in supplements or to fortify various foods.

What Is Vitamin D3?

(Credit: Iryna Imago/Shutterstock)

D3, meanwhile, is known as cholecalciferol and tends to come from fish and meat. However, D3 is also the form of vitamin D that humans can produce themselves. Our bodies are actually able to synthesize D3 when our skin is exposed to direct sunlight. Unfortunately, given the well-known risks of excessive sun exposure, most people these days don’t get enough sun to make sufficient amounts of D3 for their body’s needs. D3 is also used to fortify some foods and is widely available in supplements.

Is Vitamin D3 Better Than D2?

Although D2 and D3 are very similar, there are a couple of other differences worth noting: Given their sources, people who observe vegan diets may prefer to take vitamin D2 (although there are vegan D3 supplements available that are derived from certain forms of algae and fungi). As a supplement, D2 also tends to be a little cheaper than D3 supplements.

What Body Functions Does D2 vs. D3 Support?

Both forms of vitamin D have the same benefits insofar as they help your body absorb calcium and phosphorus, which in turn helps ensure that you have strong teeth and bones. Both forms of vitamin D also work well to sustain other systems critical to good health, aiding in muscle development and recovery, as well as keeping our nervous and immune systems functioning properly. Having said that, some research has shown that vitamin D3 may be more readily absorbed in the body and is more effective than D2.

Read More: Full Vitamin D Deficiency Guide

What Are the Food Sources for Vitamin D?

Although it tends to be more widely available in supplements or in fortified foods, vitamin D can be found naturally in some food sources.

What Are the Food Sources for Vitamin D2?

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Some mushrooms, especially those irradiated with UV light, contain vitamin D2. But mainly, vitamin D2 is derived from yeast and fungal sources in order to fortify other foods or be used in supplements. Milk and other dairy products, non-dairy milk (such as soy and almond), and some cereals are common foodstuffs fortified with vitamin D2. Always check the labels first to determine what form of vitamin D is present in the food you’re buying.

What Are the Food Sources for Vitamin D3?

(Credit: Ekaterina Markelova/Shutterstock)

You can find vitamin D3 naturally in fatty and oily fish, such as trout, salmon, swordfish, and sardines. You’ll also find it in egg yolks and most red meats, as well as beef liver. Vitamin D3 is also used to fortify various dairy products and orange juice (again, read the nutritional labels to confirm the exact amount).

Read More: 20 Best Vitamin D Supplements

Diseases and Symptoms of Vitamin D Deficiency

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Like any vitamin deficiency, if you don’t get enough vitamin D — regardless of whether it’s D2 or D3 — your body will be at risk for a variety of health problems. According to the Cleveland Clinic, as many as 1 billion people worldwide suffer from some form of vitamin D deficiency. Such a deficiency can lead to conditions ranging from bone and joint deformities, heart disease and other circulatory problems, immune disorders, and neurological and psychological problems, among many others.

Common symptoms of vitamin D deficiency can include bone, joint, and muscle pain, as well as depression and other mood conditions. In older people, vitamin D deficiency can increase the risk of falls, which can potentially be fatal to that demographic. The best and simplest way to avoid these problems is to make sure you get enough vitamin D from a combination of diet, supplements, and exposure to sunlight.

Read More: 15 Signs of Vitamin D Deficiency

What Is the Correct Dosage of Vitamin D?

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Despite their differences, both vitamin D2 and D3 can help your body absorb calcium, and dietary guidelines typically do not offer different recommended amounts for either form of the vitamin. According to the National Institutes of Health’s Office of Dietary Supplements, the current recommended daily amount for vitamin D (in micrograms or International Units) is mainly determined by age as follows:

  • Children under 12 months: 10 mcg or 400 IU

  • Children/Teens 1-18: 15 mcg or 600 IU

  • Adults 19-70: 15 mcg or 600 IU

  • Adults 71 and older: 20 mcg or 800 IU

  • People who are pregnant or breastfeeding, the recommendation is 15 mcg or 600 IU.

So don’t worry about the number attached to each type of vitamin. Instead, focus on checking labels and getting the necessary daily amount that you need to stay healthy.

Read More: What Is the Correct Dosage of Vitamin D for Adults?

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