Not getting enough vitamin D can weaken bones, teeth, and muscles by interfering with calcium absorption. Lack of the vitamin has also been implicated in dementia and an increased risk of colorectal cancer. Now there's another reason to avoid a serious D deficiency: it can make respiratory tract infections much worse, according to a new study.
It might not be a simple coincidence that respiratory infections like bronchitis and pneumonia spike during the winter months, when sunlight is in short supply. It might have to do with the fact that when we go a while without catching any rays, our vitamin D levels can dip, which can impact our immune systems and allow these types of infection to flourish.
"Vitamin D is vital to our physical wellbeing," says PhD researcher Abi Bournot from the University of Surrey (UOS) in England. "Not only does it keep our bones and muscles healthy, its antibacterial and antiviral properties are also thought to help reduce the risk of respiratory tract infections that can lead to hospitalisation. 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."
Examining the link between vitamin D and lung infections, Bournot and other researchers from UOS, along with researchers from the University of Reading and University of Oxford looked at data from the UK Biobank, a massive depository of health data collected from 500,000 volunteers since 2006. In what is considered the largest study of its kind, they isolated 36,258 participants from the Biobank and discovered that people who had severe vitamin D deficiency of below 15 nmol/L (nanomoles per liter) were 33% more likely to be hospitalized for a respiratory tract infection than those who had normal levels of the vitamin, which is considered to be 75 nmol/L or more.
Furthermore, they found that for each 10 nmol/L increase in vitamin D, the hospitalization rate due to respiratory tract infections went down by 4%.
"Supplementation of the vitamin, especially in the winter months when our exposure to sunlight is limited, is an effective way of increasing vitamin D and reducing the risk of serious respiratory tract infections," adds Bournot. "This 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."
According to the researchers, lower respiratory tract infections – as opposed to those that attack the upper respiratory tract like the common cold and sinusitis – are in the top 20 leading causes of mortality around the world for adults between the ages of 50 to 74, and in the top 10 for those older than 75.
"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 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,” concludes study co-author Andrea Darling, referring to the UK's National Health Service.
The study has been published in the American Journal of Clinical Nutrition.
Source: University of Surrey
