The claim: A cup of coffee can ease symptoms of asthma.
The facts: Caffeine is known more as a pick-me-up than a home remedy but, for years, scientists have wondered whether it may have benefits for people with asthma.
The suspicion stems in part from its chemical structure, which resembles that of theophylline, a common asthma medication that relaxes the airway muscles and relieves wheezing and other respiratory problems.
In fact, when caffeine is ingested and broken down by the liver, one by-product is small amounts of theophylline.
In a 2007 study in the Cochrane Database Of Systematic Reviews, researchers analysed the results of half a dozen clinical trials looking at the effects of caffeine on asthmatics.
They found that caffeine produced small improvements in airway function for up to four hours, compared with a placebo. Even a small dose - less than the amount in a cup of Starbucks coffee - could improve lung function for up to two hours.
However, studies show the improvements are very slight and not enough to make caffeine a replacement for medication.
The other problem is that because of their chemical similarities, consuming too much caffeine can compound any side effects of theophylline.
As a result, doctors advise people taking that medication to watch their consumption of foods with caffeine.
The bottom line: Caffeine’s benefits for asthma are real but minimal.
- The New York Times