Introduction to Vitamin D
Vitamin D is known to be essential for many aspects of human health. However, a new study suggests that taking a certain form of it may have negative effects. The more potent and longer-lasting form, vitamin D3 (cholecalciferol), is produced naturally when the body is exposed to sunlight and is also found in animal products, while vitamin D2 (ergocalciferol) comes from plant or fungal sources.
Study Findings
Researchers at the University of Surrey in the United Kingdom found that taking vitamin D2 can lead to reduced levels of vitamin D3 in the body. They came to this finding by analyzing 11 randomized controlled trials involving 655 adults, which showed that people who took vitamin D2 supplements had less vitamin D3 than those who did not take D2.
Immune System Effects
The study also found that vitamin D3, but not vitamin D2, appears to stimulate the type I interferon signaling system in the body – an important part of the immune system that provides a first line of defense against bacteria and viruses. A healthy vitamin D3 status can help prevent viruses and bacteria from gaining a foothold in the body.
Public Health Implications
Vitamin D deficiency is a significant public health problem, particularly in the winter months. Further research is needed to determine whether vitamins D2 and D3 affect the body differently – and whether this could change doctors’ medical advice about taking them.
Limitations of the Study
There were several limitations to the analysis, including a small number of studies with many differences, such as their duration, the amount and timing of doses, and the way outcomes were measured. There was also the possibility of bias due to incomplete reporting of details. The results could also be influenced by factors such as the amount of sun exposure, as well as how some people take supplements and eat foods fortified with vitamins.
Food Sources of Vitamin D
Some foods that contain vitamin D3 include fatty fish, egg yolks, cod liver oil, and fortified dairy and pet foods. Vitamin D2 is found in mushrooms, fortified foods, and some plant/mushroom-based supplements. The study was supported by the Biotechnology and Biological Sciences Research Council (BBSRC).
