Many people take vitamin D supplements, especially during the colder months when there is less sunlight. Vitamin D is important for strong bones and a healthy immune system.
But new research from the University of Surrey and its partners suggests that not all forms of vitamin D are the same—and one type might even lower the levels of the other in your body.
There are two main types of vitamin D used in supplements: vitamin D2 and vitamin D3. Vitamin D3 is the form our bodies naturally make when our skin is exposed to sunlight.
It’s also the more effective type when it comes to raising vitamin D levels in the body. Vitamin D2 is found in some plants and fungi and is also used in many fortified foods and supplements.
The new study, published in Nutrition Reviews, looked at results from many earlier clinical trials. The researchers found that people who took vitamin D2 had lower levels of vitamin D3 in their bodies compared to those who didn’t take D2. In fact, in many of the studies, people taking vitamin D2 ended up with even less vitamin D3 than those in the control groups.
Dr. Emily Brown, who led the research at the University of Surrey, said that while vitamin D supplements are important during months with little sunlight, people should know that taking vitamin D2 may actually reduce the amount of vitamin D3 in the body.
This was a surprising finding that hadn’t been fully understood before. She added that, in most cases, vitamin D3 supplements might be the better choice.
Professor Cathie Martin from the John Innes Center pointed out that there should be better access to plant-based forms of vitamin D3 in the U.K., especially for people who follow vegan or vegetarian diets.
This study supports previous research that showed vitamin D2 and D3 may not work the same way in the body. A study published in Frontiers in Immunology, led by Professor Colin Smith from the University of Surrey, found that vitamin D3 helps strengthen the immune system in ways that vitamin D2 does not.
Specifically, vitamin D3 seems to boost a part of the immune system called type I interferon signaling. This system helps fight off viruses and bacteria in the early stages of infection.
Professor Smith explained that having enough vitamin D3 may help your body stop infections before they get serious. This gives another reason why vitamin D3 might be the better choice for most people.
Professor Martin Warren from the Quadram Institute added that vitamin D deficiency is a big health concern in the U.K., especially during the winter. He stressed the importance of using the most effective form of vitamin D in supplements and food to improve public health. This fits with the goal of making the foods we eat healthier and more nutritious.
Together, these findings suggest that while both forms of vitamin D can be useful, vitamin D3 may be the better option for most people. More research is still needed, but for now, it may be worth choosing a vitamin D3 supplement—especially if you want the best support for your bones and immune system.
If you care about nutrition, please read studies that vitamin D can help reduce inflammation, and vitamin K may lower your heart disease risk by a third.
For more health information, please see recent studies about foods that could sharp your brain, and results showing cooking food in this way may raise your risk of blindness.
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