Vitamin D deficiency linked to higher risk of hospitalisation for respiratory infections

Vitamin D deficiency may put people at higher risk for being admitted to hospital for respiratory infections such as bronchitis and pneumonia, say UK researchers.

Analysis of Biobank data of middle-aged and older adults found that those with a severe deficiency (below 15 nnmol/L) were 33% more likely to be admitted to hospital for treatment than those with sufficient levels of vitamin D (at least 75 nmol/L).

The analysis of more than 36,000 participants also showed that for every 10 nmol/L increase in vitamin D, the hospitalisation rate for respiratory tract infections decreased by 4%.

More research is needed to explore the mechanisms that may explain the association between vitamin D status and respiratory tract infections in different ethnic groups, they concluded in the American Journal of Clinical Nutrition.

The analysis did not find significant associations between hospital admissions for respiratory infections and vitamin D levels at 15 to 24 nmol/L, 24 to 49 nmol/L, or 50 to 74 nmol/L.

In the UK, substantial disparities in respiratory tract infection-related hospitalisation and mortality among ethnic groups have been reported, with several dark-skinned ethnic groups at a higher risk compared with white populations, they noted.

These disparities have not been fully explained by sociodemographic characteristics and comorbidities, indicating that other factors may be involved, they added.

Lead author, Abi Bournot from the University of Surrey, said vitamin D was known to have antibacterial and antiviral properties which are thought to help reduce the risk of respiratory tract infections that can lead to hospitalisation.

‘This research attaches hard data to support the theory,’ she added.

‘Despite its importance to our overall health, many people are deficient and do not meet the government’s recommended intake of 10 micrograms of vitamin D per day.

Supplementation is particularly important for older people who are at higher risk of death from such infections, and ethnic minority communities in the UK, who are at a higher risk of vitamin D deficiency, she added.

Co-author Dr Andrea Darling said: ‘Our findings of a significant association between increased vitamin D levels in our bodies and reduced hospital admission rates warrants further study and points to the potential for vitamin D supplementation and the consumption of vitamin D fortified foods to reduce the risk of hospitalisation with respiratory infections in the future, and therefore mitigate pressures on the NHS.’

Other research has found that taking vitamin D is not protective against respiratory tract infections.