Vitamin D is one of the most popular dietary supplements in the world. Many people take it to keep their bones strong, support their immune system, and maintain overall health.
It becomes especially important during the winter months, when sunlight is limited and the body cannot produce enough vitamin D naturally.
Our bodies usually make vitamin D when our skin is exposed to sunlight. When sunlight hits the skin, it triggers a process that produces a form of vitamin D called vitamin D3. This form is considered the most natural and efficient type because it is the same one our bodies create.
However, when sunlight is weak or when people spend most of their time indoors, the body may not make enough vitamin D. This is why doctors often recommend vitamin D supplements, particularly during the colder months.
But new research suggests that not all vitamin D supplements work in the same way.
Scientists from the University of Surrey, the John Innes Centre, and the Quadram Institute Bioscience recently studied two common forms of vitamin D supplements. These forms are known as vitamin D2 and vitamin D3.
Both types are widely available in pharmacies and health stores. Many people assume that the two forms work equally well. However, the new study suggests that this may not be the case.
The researchers analyzed results from several clinical trials to understand how these supplements affect vitamin D levels in the body. They focused on how vitamin D2 and vitamin D3 influence the amount of vitamin D circulating in the blood.
The findings were surprising.
When participants took vitamin D2 supplements, their blood levels of vitamin D3 actually decreased. This means that while the supplement added vitamin D2 to the body, it appeared to reduce the amount of the more useful vitamin D3.
Vitamin D3 is important because it is the form that the body naturally produces when exposed to sunlight. It is also considered more effective at increasing and maintaining healthy vitamin D levels.
In several of the trials analyzed by the researchers, people who took vitamin D2 ended up with lower vitamin D3 levels than people who did not take any vitamin D supplements at all.
This suggests that vitamin D2 may not support vitamin D status as effectively as vitamin D3.
Dr. Emily Brown, the lead researcher from the University of Surrey, explained that vitamin D supplements are especially important during the winter months. In countries like the United Kingdom, sunlight between October and March is often too weak for the body to produce enough vitamin D naturally.
Because of this, many health authorities encourage people to take supplements during these months.
However, the study shows that the type of supplement people choose may matter.
“Our research shows that vitamin D2 supplements can reduce levels of vitamin D3 in the body,” Dr. Brown explained. “This suggests that vitamin D3 may be a better option for most people who want to increase their vitamin D levels.”
The new findings support earlier research showing that vitamin D2 and vitamin D3 behave differently in the body.
In a previous study published in the journal Frontiers in Immunology, scientists from the University of Surrey discovered that vitamin D3 appears to activate an important part of the immune system called the type I interferon signaling system.
This system plays a key role in helping the body defend itself against bacteria and viruses. The researchers found that vitamin D3 stimulated this immune response, while vitamin D2 did not appear to have the same effect.
Maintaining healthy vitamin D levels is important for many aspects of health. Vitamin D helps the body absorb calcium, which is necessary for building strong bones and teeth. It also plays a role in muscle function, immune defense, and reducing inflammation.
Despite its importance, vitamin D deficiency is common in many parts of the world. This is especially true during winter, when people get less sunlight.
Professor Martin Warren from the Quadram Institute Bioscience explained that choosing the most effective form of vitamin D could help improve public health. If people receive the right type of supplement, it may help reduce vitamin D deficiency across large populations.
Professor Cathie Martin from the John Innes Centre also pointed out that developing plant-based sources of vitamin D3 could make this form of the vitamin accessible to more people, including those who follow vegetarian or vegan diets.
Although vitamin D3 appears to offer several advantages, the researchers say more studies are still needed to fully understand the differences between vitamin D2 and vitamin D3.
For now, the evidence suggests that vitamin D3 may be the better option for people who want to maintain healthy vitamin D levels.
If you care about nutrition, please read studies about why vitamin K is so important for older people, and this snack food may harm your heart rhythm.
For more health information, please see recent studies about vitamin that may protect you from type 2 diabetes, and results showing this common chemical in food may harm your blood pressure.
The study was published in the scientific journal Nutrition Reviews.
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