Vitamin D2 supplements may reduce levels of vitamin D3 in the body, study finds

Concerns Over Vitamin D2 and Its Impact on Vitamin D3 Levels

Vitamin D plays a crucial role in human health, but recent research indicates that some forms might have unintended negative effects. According to the National Institutes of Health, vitamin D3 (cholecalciferol), which is more potent and longer-lasting, is produced naturally when skin is exposed to sunlight. It’s also found in animal products. On the other hand, vitamin D2 (ergocalciferol) comes from plant and fungal sources.

Researchers at the University of Surrey in the UK found that taking vitamin D2 supplements could actually lower vitamin D3 levels in the body. This conclusion was reached after analyzing 11 randomized controlled trials with 655 participants, revealing that individuals who took vitamin D2 had decreased vitamin D3 levels compared to those who didn’t.

Lead researcher Dr. Emily Brown emphasized the importance of vitamin D supplements in the UK, particularly from October to March, when the body cannot synthesize vitamin D from sunlight. However, he pointed out that vitamin D2 could reduce levels of the more beneficial vitamin D3, suggesting that the latter may be preferable for most people, dependent on individual circumstances.

Previous studies support that vitamin D2 and D3 are not interchangeable. For instance, another study from the University of Surrey published in Frontiers in Immunology demonstrated that vitamin D3 enhances the immune system and is more effective against bacterial and viral infections.

Professor Colin Smith, who led the study, noted, “Vitamin D3 seems to stimulate the type I interferon signaling system, which plays a crucial role in the immune response against pathogens.” In contrast, Professor Martin Warren from the Quadrum Institute highlighted vitamin D deficiency as a significant public health issue, especially during winter months.

The research team acknowledged that more investigation is needed to clarify how vitamins D2 and D3 affect the body differently, which could alter medical recommendations regarding supplementation. However, they recognized several limitations in their analysis, including the small number of studies examined and variability in study design.

Additionally, factors like sunlight exposure and dietary intake of fortified foods may also affect the results. Foods high in vitamin D3 include fatty fish, egg yolks, cod liver oil, and fortified dairy products, while vitamin D2 is typically found in mushrooms and some fortified foods.