GUILDFORD, United Kingdom — Vitamin D helps with strong bones, immunity, and improving mood. But new research suggests vitamin D3 specifically is more beneficial than vitamin D2.
While the researchers call vitamin D2’s effects on human health “questionable,” they say vitamin D3 may balance the immune system and bolster defenses against viral infections including COVID-19. These conclusions are based on observations made during a 12-week experimental period in which participants took either a D2 or a D3 supplement daily. The research team looked at how the two varieties of vitamin D influenced the activity of genes in participants’ blood.
Results contradict previous beliefs that all vitamin D is the same
These findings contradict the widely held belief that vitamin D2 and D3 provide similar health benefits. Vitamin D3 appears much more helpful to the immune system, providing a “modifying effect” that strengthens the body’s defenses against viral and bacterial diseases.
“We have shown that vitamin D3 appears to stimulate the type I interferon signaling system in the body – a key part of the immune system that provides a first line of defense against bacteria and viruses. Thus, a healthy vitamin D3 status may help prevent viruses and bacteria from gaining a foothold in the body,” says lead study author Professor Colin Smith from the University of Surrey, who began this work while at the University of Brighton, in a press release. “Our study suggests that it is important that people take a vitamin D3 supplement, or suitably fortified foods, especially in the winter months.”
Where to find vitamin D2 and vitamin D3
While some commercially available foods (breakfast cereals, yogurt, and bread) are “fortified” with vitamin D, few foods naturally contain vitamin D. Luckily, our bodies produce vitamin D3 naturally whenever sunlight (or artificial ultraviolet UVB light) touches our skin. Certain plants and fungi produce vitamin D2.
Many people have a vitamin D3 deficiency because they live in areas that get little sunlight. The COVID-19 pandemic, and constant calls to stay home, have only sped up this troubling trend.
“While we found that vitamin D2 and vitamin D3 do not have the same effect on gene activity within humans, the lack of impact we found when looking at vitamin D2 means that a larger study is urgently required to clarify the differences in the effects. However, these results show that vitamin D3 should be the favored form for fortified foods and supplements,” concludes study co-author Professor Susan Lanham-New, Head of the Department of Nutritional Sciences at the University of Surrey.
The study is available to read in Frontiers in Immunology.