New Insights on Vitamin D: Study Highlights D2 Supplements’ Impact on D3 Levels

A recent study sheds light on the effects of vitamin D2 supplements, suggesting they may decrease blood levels of vitamin D3, the more efficiently utilized form by the body. This new research, involving 1,080 participants across 20 studies, found that those consuming vitamin D2 supplements experienced an 18 nanomoles per liter (nmol/L) reduction in their vitamin D3 levels compared to those who did not take supplements.

While the study's lead researcher, Emily Brown, ANutr, suggests that this drop is significant, it doesn't necessarily cause a deficiency that endangers health. Blood levels of vitamin D below 30 nmol/L are associated with adverse health outcomes, so maintaining adequate vitamin D levels remains crucial.

Vitamin D3 not only raises total vitamin D levels more effectively than D2, but it also provides added immune health benefits. However, Brown emphasizes that D2 is not harmful and can still be used by those who need supplementation, noting that D3 is generally preferred due to its efficiency.

Considerations for D2 Supplement Users

Vitamin D2 is sourced from plants, making it a suitable option for individuals following vegan or plant-based diets who might have limited access to animal-derived D3. Dietitians advise that supplementation, whether D2 or D3, should be individualized based on dietary preferences and nutritional needs. Sue-Ellen Anderson-Haynes, MS, RDN, advocates for consulting a healthcare provider to determine the appropriate supplement choice for one’s diet.

Plant-based foods like mushrooms, fortified soy milk, and fatty fish such as salmon can help individuals meet their vitamin D needs. Additionally, vegan vitamin D3 supplements made from lichen are available as an alternative.

Dietary Sources and Requirements

Though whole food sources are favored over supplements, few foods naturally provide significant amounts of vitamin D. In the United States, most dietary vitamin D is obtained from fortified products, including dairy and plant-based milks and cereals. Naturally vitamin D-rich foods include fatty fish, certain mushrooms, and eggs.

Adults typically require 600 to 800 International Units (IU) of vitamin D daily. While diet and sun exposure contribute to meeting these needs, factors like skin pigmentation and seasonal changes can impact vitamin D synthesis. Supplements serve to bridge the gap where natural sources fall short.

However, caution is advised against excessive supplementation; doses exceeding 1,000 IU, and particularly those over the 4,000 IU upper limit, may lead to adverse effects such as nausea, confusion, dehydration, and kidney stones.

Conclusion

This study underscores the importance of personalized supplementation strategies for vitamin D, highlighting the differing impacts of D2 and D3 on overall health. While supplementation is beneficial for many, individuals must balance intake carefully to avoid excessive consumption and its potential health risks.