One vitamin was found to be helpful in fighting off viral infections - including covid - in a new study.
Taking vitamin D3 appears to balance and defend immune systems, according to research from the University of Surrey.
Experts compared the effect of taking both types of vitamin D - D2 and D3 - in the gene activity in participants' blood, the Daily Record reports.
READ MORE: Vitamin B12 deficiency: Symptoms and warning signs in your mouth that suggest low levels
The study found the latter triggered a vital part of the immune system.
Not all vitamins are the same, even if they sound very similar, and vitamins D2 and D3 do not have the same effect on the body.
Lead author Professor Colin Smith said: "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 defence against bacteria and viruses.
"Thus, a healthy vitamin D3 status may help prevent viruses and bacteria from gaining a foothold in the body."
He added: "Our study suggests it is important people take a vitamin D3 supplement, or suitably fortified foods, especially in the winter months."
Researchers urgently called for further research into the effects of vitamin D2, but concluded with a recommendation for vitamin D3 fortified foods and supplements - especially during the winter.
Co-author Professor Susan Lanham-New said: "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 favoured form for fortified foods and supplements."
Vitamin D is essential for keeping our bodies in tip top condition.
It helps keep bones, teeth and muscles healthy by controlling the body's amount of calcium and phosphate.
You naturally produce vitamin D3 through sun exposure, which is why our bodies tend to lack it in winter when sunlight is fleeting - especially in the UK.
There aren't many food sources of vitamin D3, but the best sources are fatty fish (like salmon and tuna), as well as in supplements.
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