photo of a woman with a pill symbol of the vitamin D

The role of vitamin D in immunity

Vitamin D is the go-to vitamin for keeping our bodies healthy and our immunity high.

Among all vitamins that help the body fight off infections, vitamin D is the most important vitamin to take. If you know you’re prone to seasonal allergies or catching the flu, then taking vitamin D all-year-around might be a good choice.


In a study by Mikhail V. Bychinin & Co. published in ‘Scientific Reports’ journal in November 2022, patients with Covid-19 in a hospital setting were split into two groups. One group received a weekly dose of 60.000 IU of vitamin D3, followed by a daily dose of 5000 IU, while the second group received placebo pills.

After a week, patients who got the highest number of vitamin D3 showed higher levels of NK and NKT cell counts (NK=natural killer cells, NKT=natural killer T cells), reduced inflammation in the body and faster recovery from Covid-19, while those in the placebo group took longer to recover. The study concluded that vitamin D has an important role in immunity during infection with the novel coronavirus.

It was proven that it simulates the production of antimicrobial and antiviral peptides that fight off the infection and restores the body’s healthy state in a short amount of time.

Another study shows that vitamin D reduces the risk of mortality in cancer patients. Harvard scientists gave 2000 IU of vitamin D daily to 25,871 people who were 50 or older. The group was split into participants who took vitamin D and those who took placebo pills. The results showed that the rate of fatal cancer was lower by 17% in the group who took vitamin D daily.


Vitamin D is a powerful immune booster that helps you recover faster from a respiratory illness or other types of infection. You can’t get enough vitamin D from foods so you’d need to take supplements. Don’t forget to go for at least 2000 IU a day especially if you suffer from a cold and you feel extra tired.

Author’s Bio

Marlena Bontas is a freelance writer with a passion for health, technology and mental wellness. She has an MA in Psychology from the University of Helsinki and is currently travelling. Write her on Twitter at @MarlenaEeva.

Leave a Reply