Vitamin D

Vitamin D vs. D3: Is There a Difference?


If you’ve looked into multivitamins or nutritional supplements, you’ve likely heard of vitamin D and seen it on a nutrition label. Or maybe you’ve bought milk, orange juice, or breakfast cereals that are fortified with vitamin D.

If you’ve looked a little closer at the nutrition label, you might have seen that the specific ingredient listed is vitamin D3.

So, what’s the difference between vitamin D and vitamin D3? Is it something you should look out for?

This article seeks to answer those questions. We’re going to break down what vitamin D and vitamin D3 are so that you can have a clear understanding next time you’re buying a product with them in it. Let’s get started.

What Is Vitamin D?


Vitamin D is a fat-soluble vitamin that is an incredibly important element of our diet. Vitamin D is one of the 13 essential vitamins, alongside vitamins A, C, E, K, and B complex.

Essential vitamins are vitamins that your body cannot produce enough of on its own; therefore, they need to be consumed through the diet to get adequate amounts of them.

Vitamin D is responsible for several different bodily functions. In fact, scientists are still learning all about how vitamin D is important to our bodies. But the main function of vitamin D is for the absorption of key minerals like calcium and phosphorus.

What Is it Used For?

Vitamin D has several different functions and benefits for our bodies — there are vitamin D receptors in nearly every part of the human body.

Most health professionals will tell you that your body needs about 600 IU (international units) of vitamin D every day — but why? Here are just a few reasons why vitamin D is so crucial.

Supports Musculoskeletal Health

For starters, vitamin D supports bone health and muscle function. As mentioned above, without vitamin D, your body cannot absorb calcium and phosphorus. Calcium, in particular, is one of the most important building blocks for the bone, and it’s also required to maintain healthy muscle function.

Calcium supports bone strength, and without vitamin D, the calcium you consume goes to waste. Therefore, vitamin D helps to support your bones and support the healthy function of your musculoskeletal system through calcium absorption.

Vital for Overall Wellness

Vitamin D also supports immune system function. 

Vitamin D is used throughout the immune system in a variety of ways. Our amazing immune system is made up of two parts: the innate (as in, we're born with it) immune system, and the adaptive (also called "acquired") immune system. Vitamin D has been shown to play a critical role in both parts.

As part of the first line of defense against invaders, the innate immune system uses macrophages — the little Pac-Man guys that gobble up invading bacteria — and vitamin D promotes the response to pathogens by our macrophages.

Our acquired immune system, which learns over time how to respond to illness, utilizes T-cells to circulate and constantly watch out for specific invaders that we've encountered in the past. You guessed it--vitamin D plays a crucial role in the function of T-cells, too.

In fact, researchers even have gone as far as saying that vitamin D is a key factor linking innate and adaptive immunity, and both of these functions may be compromised when we don't get enough vitamin D.

Supports Bodily Functions

Vitamin D also plays a role in various everyday functions of your body. For example, vitamin D helps support the regular production of cytokines, which work to regulate responses to foreign pathogens, injuries, and more.

These types of bodily responses are important for healthy immune system function but also for wounds and gastrointestinal function.

What Are the Different Types of Vitamin D?

Sun Vitamin D

Now let’s get to the main question: is there a difference between vitamin D and vitamin D3?

The answer is that “vitamin D” is used almost as a generic term within medical literature, but when it comes to supplements, “vitamin D” will be either in the form of vitamin D2 or vitamin D3. There is no supplement option for just “vitamin D.” To help bring clarity to how vitamin D3 is different, let’s compare the various types of vitamin D.

Vitamin D2

The first type of D vitamin is vitamin D2, also called ergocalciferol. It’s also known as pre-vitamin D. It is an effective vitamin, and it works to raise your vitamin D levels, but it perhaps isn’t the most productive D vitamin for the body.

The body has to process vitamin D2 into D3 for it to be used properly — that doesn’t mean that D2 is ineffective or bad, it just means that D3 is ready for your body to use, while D2 needs a bit more work.

Vitamin D2 is typically found in plant sources, especially in fungi like mushrooms. And if you see a food product like milk, orange juice, or fortified cereals that are fortified with vitamin D, it is most likely fortified with D2.

Vitamin D3

Vitamin D3, also called cholecalciferol, is considered to be a better form of vitamin D. It is more effective at raising blood levels of vitamin D (in the form of 25-hydroxyvitamin D) and can sustain those results for longer than D3. This is because cholecalciferol isa form of vitamin D very recognizable to your body — read on and you’ll see why!

Vitamin D3 is typically found in animal sources, such as oily fish like salmon, tuna, cod, sardines, and swordfish. If you don’t eat fatty fish, you can also find it in beef liver and egg yolk.

But the main source of D3 is actually your own body. When ultraviolet (UV) rays hit your skin, your skin produces small amounts of D3, cholecalciferol, that your body can use. However, UV light and your skin can’t produce enough vitamin D for your whole body, which is why vitamin D is still considered an essential vitamin.

Because your body can produce this nutrient with the help of the sun, vitamin D has been nicknamed the sunshine vitamin.

Vitamin D Deficiency

Many people in the United States have vitamin D deficiency. This is when your body doesn’t get enough vitamin D from the sun and your diet. Vitamin D deficiency can have several negative symptoms, including poor immune response, mood swings, lack of energy, problems with the skin, increased risk of bone fracture, increased risk of muscle or tendon injury, and more.

Unfortunately, this vitamin deficiency is relatively common. By some estimates, approximately 42% of Americans have low levels of vitamin D and are therefore at higher risk of developing the symptoms mentioned above.

Over-the-counter vitamin D supplements are becoming more and more common. Specifically, vitamin D3 supplements have been popping up on pharmacy shelves everywhere. Vitamin D3 is also a common ingredient in multivitamins and other dietary supplements.

Certain people are more at risk of getting low levels of vitamin D. Here are some of the risk factors that could be affecting your vitamin D levels.

Minimal Sunshine

For starters, not getting enough sunshine can put you at risk of not getting enough vitamin D. Getting outside is a great way to give your body a boost of vitamin D, but if your lifestyle doesn’t get you any vitamin D, your levels may fall.

For many people, this has to do with where they live. People who live in a place that gets little sun exposure may be more at risk. People who work night shifts and sleep during the day also might have low levels.

High Levels of Melanin

Melanin is a pigment in the skin that makes it darker, so black people have high amounts of melanin, giving their skin its characteristic look.

But melanin can somewhat act like shade and lower the amount of D3 that your skin makes. Those with darker skin tones, and thus more melanin, might be at higher risk of low vitamin D levels.

Plant-Based Diets

Finally, plant-based diets can cause people to not get much vitamin D. Most of the sources of vitamin D, and especially D3, are animal products. So if you have a vegan or vegetarian diet, you might not be able to get much vitamin D through your diet.

Vitamin D Supplements

iwi Mens Multivitamin

Because many people struggle to get enough vitamin D in their diet, many people are turning to vitamin D supplements or multivitamins with vitamin D to bridge the gaps in their diet and get the nutrients they need.

It’s important to get an adequate amount of vitamin D in your diet, and for many, a supplement is needed to do just that.

A Vitamin To Support Your Health

Vitamin D is an incredibly important vitamin. And now you know what it means when you see D3 on a label, and you can tell the difference between vitamin D and D3. With iwi life, you can get all of the vitamin D your body needs to support your health — and more!


42% Percent of Americans Are Vitamin D Deficient. Are You Among Them? | Cleveland Clinic

Vitamin D | The Nutrition Source | Harvard TH Chan School of Public Health

Vitamin D and immune function: an overview | PubMed

Vitamins and Minerals for Older Adults | National Institute on Aging

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