Low vitamin D levels associated with higher respiratory illness risk among elderly

The study, published in the Journal of the American Geriatrics Society, used data from the 2005 Health Survey for England. The study included data from 2,070 noninstitutionalized individuals aged 65 and older.

The study author, Vasant Hirani, PhD, found that people with severely deficient vitamin D levels, less than 35 nmol/L, had more than twice the risk of respiratory disease when compared to those in the highest vitamin D quartile, greater than 64 nmol/L, after adjustments for covariates. The risk dropped with greater vitamin D levels;  1.75  times for the second quartile and slightly higher for the third. The study concluded that low serum 25(OH)D concentrations are associated with respiratory disease.

Ensuring adequate 25(OH)D levels is of public health importance for older populations living in northern latitudes and may be an effective way to prevent concurrent respiratory infections and related complications in older people.

Impaired immune response​

There are biologically plausible reasons why serum 25(OH)D may be associated with respiratory health, Hirani wrote, as inadequate vitamin D concentrations can impair the response to respiratory virus infection in the lung.

This is not the first study to report an association between lower vitamin D levels and a higher risk of respiratory disease. A study published in 2010 by researchers from Yale University found that people who had vitamin D levels greater than 38 ng/ml were associated with lower risk of developing acute respiratory tract infections. A more recent study conducted in 2011 in Mongolia, another high latitude location, found that vitamin D supplementationcut the risk of respiratory infection by half among children.

Recently, the US Institute of Medicine revised the recommended vitamin D intakes upward, to 600 IU/day for adults and 800 IU/day for people older than 70. Dr. Robert Heaney, a vitamin D researcher at the Creighton Univeristy School of Medicine in Omaha, NE, recommends people achieve a daily intake of 35 IU of vitamin D per day per pound (75 IU per kg) to help ensure reaching optimal levels vitamin D blood levels of 40 ng ml.

“Vitamin D is safe, inexpensive and represents a tremendous opportunity to reduce the personal and economic impact of respiratory diseases,” ​notes Perry Holman, of the nonprofit Vitamin D Society, a Canadian advocacy group.  Holman notes that more than half of Canada’s population falls below the recommended blood levels of vitamin D, putting them at greater risk for respiratory infections. The group estimates the cost of respiratory diseases in Canada at 6.5% of total health care costs or $12.4 billion annually.

Source: Journal of the American Geriatrics Society​
May 6, 2013, doi: 10.1111/jgs.12254​

"Associations Between Vitamin D and Self-Reported Respiratory Disease in Older People from a Nationally Representative Population Survey"​

Author: Vasant Hirani, PhD