New research on asthma is giving tantalizing hints that it may be possible to diminish symptoms of the debilitating breathing disorder by using vitamin D.
A study, based on children with asthma in Costa Rica, has found that low blood levels of vitamin D were associated with an increased severity of the disease, with those youngsters experiencing significantly more hospitalizations, increased use of inhaled steroids, and weakened immune function. The finding is believed to be the first to establish a link between the amount of the sunshine vitamin in children, and indicators showing the intensity of asthma.
The study supports the theory "that vitamin D insufficiency may worsen asthma severity, and we suspect that giving vitamin D supplements to asthma patients who are deficient may help with their asthma control," according to a statement by Juan Celedon and Augusto Litonjua, a pair of doctors from Harvard Medical School who helped conduct the research.
A paper outlining the findings is appearing in next month's issue of the American Journal of Respiratory and Critical Care Medicine.
Indications that low levels of the vitamin may be involved in asthma could help explain the puzzling rise in the incidence of the condition in recent decades.
About one out of every 10 children in Canada is now diagnosed with the respiratory ailment, placing it among the most common early life diseases, and recognizable by the intense wheezing that is its main symptom.
The cause of asthma is currently unknown, and medical researchers have theorized it may be due to everything from indoor air pollutants and viruses to modern society being too germ-free, leaving children's immune systems underdeveloped.
But some researchers are speculating that vitamin D plays a role because the nutrient helps promote proper immune function. Among people who do not take vitamin pills, about 90 per cent of their vitamin D is made when intense summertime ultraviolet light hits cholesterol in naked skin, hence its sunshine moniker.
In Canada, it's not possible to make vitamin D this natural way for about six months every year during fall and winter.
The rapidly escalating asthma rates have occurred at the same time as a general effort to encourage summertime sun avoidance to reduce the risk of wrinkles and skin cancer. This has raised the possibility that many children's vitamin D levels have inadvertently fallen to the point of causing worsening asthma symptoms.
Another intriguing recent finding is that children born to mothers who have higher vitamin D levels during pregnancy have lower amounts of wheezing in early life.
In an interview, Dr. Celedon said that it is too early to set vitamin D supplement levels to reduce asthma symptoms because the amounts required are unknown, and further research needs to be done to prove that giving the pill actually reduces the severity of the ailment. "That needs to be tested in a clinical trial," he said.
Insufficient amounts of vitamin D were found in 28 per cent of asthmatic children in Costa Rica. Even though the country is sunny, Dr. Celedon said many children have adopted Western lifestyles of staying indoors and playing computer games.
Dr. Celedon also said the researchers weren't able to completely rule out the possibility that low levels of vitamin D were a symptom of severe asthma, rather than its cause, as children with more intense cases of the disease might be sicker and get less sun exposure.
Nonetheless, other researchers see the results supporting the idea that parents should be mindful of their children's vitamin D levels. The study "provides an additional reason to promote vitamin D supplementation in children," commented John Heffner, professor of medicine at the Oregon Health and Science University in Portland.
Although the evidence linking asthma and vitamin D shortages is tentative, U.S. researchers have begun a drug-style trial that could offer more definitive proof. Bruce Hollis, professor at the Medical University of South Carolina, said a new research project now under way involves giving pregnant women 4,000 International Units of vitamin D a day, to see if the dose prevents asthma in their offspring.
