Vitamin D deficiency linked to respiratory infection risk

Severe vitamin D deficiency is associated with a higher rate of hospitalisation for respiratory tract infections such as bronchitis and pneumonia, according to a new studyinvolving scientists from the University of Reading.

Scientists found that those with a severe deficiency (below 15 nnmol/L) were 33 per cent more likely to be admitted to hospital for treatment than those with sufficient levels of vitamin D(at least 75nmol/L).

In the largest study of its kind, analysing NHS data from the UK Biobank, researchers from Surrey, in collaboration with the University of Reading and University of Oxford,investigated the association between vitamin D status and the rate of hospitalisation due to respiratory tract infections. Middle and older-aged adults are at a high risk of developing respiratory tract infections, with lower respiratory tract infections (pneumonia and bronchitis) ranking amongst the top 20 leading causes of mortality globally for individuals aged 50-74 years and in the top 10 for those aged 75 years and older.

Professor Julie Lovegrove, co-author from the Hugh Sinclair Unit of Human Nutrition, University of Reading, said: “Our findings show an important link between vitamin D levels and hospital admissions for respiratory infections. Given that many people fall short of recommended intakes, thishighlightsthe need for better public awareness about the necessityof adequate vitamin D intake and its potential role in supporting our immune system."

Professor Ian Givens, co-author from the University of Reading, said: “This research highlights the importance of adequate vitamin D intake, particularly during winter months when sunlight exposure is limited. Simple dietary changes, such as consuming fortified foods or taking supplements, could make a real difference to people's health."

Examining data from 36,258 participants from the UK Biobank, the researchers found that those withsevere vitamin D deficiency (below 15nmol/L) had a 33 per centhigherrate ofhospitalisation for arespiratory tract infection, compared to those who had vitamin D levels of 75nmol/L or greater. Scientists also found that for each 10 nmol/L higher vitamin D, the hospitalisation rate for respiratory tract infections was four percent lower.

The study was published today (Wednesday, 21 January, 2025) in The American Journal of Clinical Nutrition.

Bournot, A. R., Hart, K. H., Johnsen, S., Givens, D. I., Lovegrove, J. A., Ordóñez-Mena, J. M., De Lusignan, S., Bartlett, D. B., Lanham-New, S. A., & Darling, A. L. (2025). Association between serum 25-hydroxyvitamin D status and respiratory tract infections requiring hospital admission: Unmatched case-control analysis of ethnic groups from the United Kingdom Biobank cohort. The American Journal of Clinical Nutrition, 101179. https://doi.org/10.1016/j.ajcnut.2025.101179