The 1-2-3s of Vitamin D, D2 and D3

If you’ve ever shopped for vitamin D supplements, you may have noticed that some tout their vitamin D3 content, while others are labeled vitamin D2. So what’s the difference? 

Imagine two nearly identical phone chargers. Both have the ability to charge your phone, but one seems to fit perfectly and charge your phone quickly while the other needs to be jimmied around or held in place in order to do its job. Both will still charge your phone, but the first one will get to a 100% battery charge while the other one might not get so high or keep the charge for very long.  

This is similar to how vitamins D3 and D2 work in the body. Both have the ability to raise your blood levels of vitamin D, but one might be more effective than the other. 

What Are Vitamin D, D2 and D3? 

Vitamin D is a nutrient your body needs to keep your bones healthy and immune system going strong. “Vitamin D” is a general term that refers to a few different forms of the vitamin. There’s the kind that’s stored in the liver – that’s what your healthcare provider looks at when you get your blood levels tested.  

But the kind you get from foods, drinks and supplements are inactive forms, called vitamin D2 (ergocalciferol) or vitamin D3 (cholecalciferol). Once these food-based forms get into the body, they undergo reactions in your liver and kidneys to create the active form of vitamin D that does all the work. 

Think of D2 and D3 as iron and steel, your liver and kidneys as the metal working tools, and vitamin D as your finished sword and armor to help protect your bones and defend your immune system! 

Is D3 Better than D2? 

Vitamin D3 is found in some animal products such as fish, meat and eggs. Meanwhile, some plant foods like mushrooms can provide D2. 

Both forms help you get what you need, but research suggests vitamin D3 may be absorbed by the body more effectively. The reasons why are still not clear, but the thought is that vitamin D3 might be a better fit for the body’s cell receptors – a part of the cell that transports D2 or D3 into the body and helps transform it into the active form of the nutrient. 

Think back to that phone charger analogy: there are two chargers, both able to conduct energy from the outlet to your phone. But one version may be a better fit and provide a stronger charge. The same is true with vitamin D2 vs. D3: both will get into your bloodstream, but D3 will raise your blood levels of vitamin D higher and will keep those higher levels longer.   

Which Vitamin D is for Me? 

Ideally you should be getting vitamin D3, since that’s the form that does a better job at preventing low levels in the body. That’s what’s in salmon, milk and whole eggs (including the yolk). It’s also the form that’s most often used in fortified foods and drinks–look for fortified nutritional beverages, breakfast cereals, plant milk alternatives and orange juice. Also look for D3 if taking dietary supplements. 

And, you can check which form you’re getting by looking at the ingredients list, found under or near the Nutrition Facts label. Ingredients are listed by weight, so vitamins usually come at the end of the list.

Talk to your healthcare provider for questions or concerns about any diet or lifestyle changes and to find a plan that's right for you.