Vitamin D2 vs D3: New Research Highlights Key Differences

Recent research from the University of Surrey, John Innes Centre, and Quadram Institute Bioscience suggests that taking vitamin D2 supplements may actually lower the body’s levels of vitamin D3, the form naturally produced from sunlight and most effective in the body.

Key Findings

• Many people take vitamin D supplements, especially in the UK winter, to support bone and immune health and meet the recommended 10 micrograms (µg) per day.

• There are two main forms of supplements: D2 (ergocalciferol) and D3 (cholecalciferol).

• Analysis of data from randomized controlled trials, published in Nutrition Reviews, revealed that D2 supplementation can reduce vitamin D3 levels, sometimes even lower than in control groups not taking D2.

Expert Insights

• Emily Brown, PhD (University of Surrey):

  “Vitamin D supplements are important, especially between October and March, when our bodies cannot make vitamin D from sunlight. However, we discovered that vitamin D2 supplements can decrease levels of D3 in the body… D3 supplements may be more beneficial for most individuals over D2.”

• Professor Cathie Martin (John Innes Centre):

  “This meta-analysis highlights the importance of ensuring plant-based vitamin D3 is accessible in the UK.”

• Professor Colin Smith (University of Surrey):

  “Vitamin D3, but not D2, stimulates the type I interferon signalling system—a crucial part of the immune system that helps defend against bacteria and viruses.”

Implications

• Vitamin D3 is more efficient than D2 in raising overall vitamin D levels and supporting immune function.

• D3 appears to have a unique role in fortifying the immune system, whereas D2 does not.

• Individuals seeking to optimize vitamin D status—especially during winter or for immune support—may consider D3 as the preferred supplement, subject to personal needs.

Public Health Perspective

• Vitamin D deficiency is a major concern in the UK, particularly in winter.

• Ensuring access to the most effective form of supplementation or food fortification is critical to improving public health.

Bottom line: While both forms can supplement vitamin D intake, D3 is generally more effective, and D2 may even reduce your natural D3 levels. Choosing the right form could make a significant difference for bone, immune, and overall health.