Vitamin D2 Supplementation May Lower Vitamin D3 Levels
ADN
Recent findings suggest that supplementing with vitamin D2 may actually reduce levels of vitamin D3 in the body, raising questions about the optimal form of vitamin D for maintaining adequate nutrient balance and overall health.
TL;DR
- D2 supplements lower blood D3 more than no supplements.
- D3 is better absorbed, but both types meet vitamin D needs.
- Medical advice is crucial for safe supplementation.
Vitamin D: New Research Sparks Fresh Debate
A recent investigation by researchers at the University of Surrey has reignited discussion over the use of vitamin D supplements. The study’s findings reveal that people taking supplements containing vitamin D2 experience a drop in their blood levels of vitamin D3—the form most efficiently processed by the body—by an average of 18 nmol/L compared to those who abstain from such supplements. According to lead researcher Emily Brown, while this decline may not be immediately dangerous, it is considered significant. Health concerns generally arise when vitamin D levels fall below 30 nmol/L.
D2 or D3: What’s the Difference?
Understanding the distinction between these two forms matters. D2, mainly sourced from plants, offers a clear advantage to those following a vegan diet. By contrast, D3, derived from animal sources, is known for its superior absorption and effectiveness in supporting the immune system—a point underlined by previous studies as well. Nevertheless, experts do not advise abandoning D2 supplements outright. Dietitian Sue-Ellen Anderson-Haynes emphasizes that ensuring an adequate intake of vitamin D—regardless of its type—is key, provided this occurs under medical supervision.
The Role of Diet and Natural Sources
Nutritionists consistently argue that food should remain our primary source of nutrients, but options rich in vitamin D are limited. In typical American diets, fortified products stand out as major contributors:
- Dairy or plant-based milks
- Fortified breakfast cereals
Naturally high sources are rare but include fatty fish such as salmon and trout, certain mushrooms like shiitake and chanterelle, and eggs.
Daily Needs and Supplementation Risks
Contrary to some misconceptions, daily requirements for adults are relatively modest—between 600 and 800 IU according to Professor JoAnn E. Manson of Harvard Medical School. Achieving these levels through sunlight or food alone can be challenging during winter or for individuals with darker skin tones, making supplementation useful. However, exceeding 4,000 IU on a regular basis brings real risks: side effects such as nausea, confusion, or kidney stones have all been documented.
Ultimately, choosing between D2 and D3 depends largely on dietary habits and personal convictions. In all cases, professional guidance remains essential to maintain healthy levels without inviting unintended health problems.