Hackers, Take Note: Study Finds Apples May Reduce Chronic Cough
Study Is Latest to Suggest Apples May Improve Lung Function, Promote Lung Health
Vienna, Va. Hackers (and we don't mean the computer kind), take note: A new study from the National Institutes of Health (NIH) reports that eating foods rich in fiber and flavonoids - found most abundantly in apples - may reduce your chronic productive cough and other respiratory symptoms.
Researchers analyzing whether diet might impact chronic productive cough - commonly experienced in persons with chronic respiratory symptoms such as chronic obstructive pulmonary disease (COPD) - reported that high consumption of fiber and fruits, specifically apples, appears to be associated with a lower incidence of cough. Their findings suggest that promoting a high-fiber, high-flavonoid diet may help reduce chronic respiratory symptoms, both in smokers and non-smokers.
Reporting in the August issue of the peer-reviewed American Journal of Respiratory and Critical Care Medicine, Dr. Lesley Butler of NIH and her colleagues noted they found an inverse association between fiber consumption and the incidence of productive cough - that is, the more fiber consumed, the lower the reported incidence of cough. Fiber consumption appears to reduce the incidence of cough even in non-smokers, as well as smokers. While fruits, vegetables and grains are the top dietary sources of fiber, an association was found only for non-citrus fruit - the higher the consumption of fruit, the lower the reported incidence of cough plus phlegm. (Source: Butler, L.M., Koh W-P. et al. American Journal of Respiratory and Critical Care Medicine August 2004; vol. 170, no. 3, pp 279-287. The paper can be accessed online at http://ajrccm.atsjournals.org/cgi/content/ )
Of all the foods examined, the most significant relationship was seen with apples. The association for apples was also seen independent of fiber, suggesting that other apple nutrients besides fiber may offer lung protection. Researchers suggested that antioxidant phytonutrients such as flavonoids may be at work.
Apples are one of the top dietary sources for fiber and flavonoids. One medium, tennis ball-sized apple contains five grams of fiber, and apples are the top fruit source of flavonoids.
"Cough and phlegm are frequently associated with [COPD], which may be caused by oxidative stress-mediated inflammation and tissue damage in the lung," wrote Butler and her colleagues. "Fruits and vegetables are the major food sources of antioxidants that may protect the lung from oxidative stress. We observed the strongest inverse dose-response associations for apples, pears and grapes." That means the more of these foods that were eaten, the greater the benefit was, with the benefit increasing in direct correlation with the amount of fruit consumed.
"Our findings suggest that flavonoids may play a crucial role," Butler and colleagues wrote. "Flavonoids may protect the lung on the basis of their antioxidant and anti-inflammatory properties."
The prospective cohort study involved 571 persons aged 45-74 reporting a productive cough, who were identified from the ongoing Singapore Chinese Health Study, a large 49,140-person epidemiological study that began in 1993. The study was supported by NIH and the National Institute of Environmental Health Services.
Diet May Impact Chronic Lung Disease
According to the American Lung Association (ALA), COPD is the fourth leading cause of death in the United States, claiming the lives of 107,146 Americans annually. ALA reports that 80 to 90 percent of COPD cases are caused by smoking; other leading causes are second-hand smoke and exposure to air pollutants.
"Our data from the Singapore Chinese Health Study provide evidence that promoting a diet high in sources of fiber and flavonoids, such as fruit and soy, may be an important contribution to primary prevention strategies for chronic respiratory symptoms, both in smokers and nonsmokers," the authors wrote.
Latest Study to Link Apples, Lung Health
The NIH study is the latest of many to suggest we might breathe easier - literally - by eating apples.
- Last fall, Australian researchers reported that eating apples and pears may protect against asthma, another growing lung health risk.
- In December 2001, London-based researchers reported that people who ate at least two apples per week had a 22-32 percent lower risk of developing asthma than people who ate fewer apples, based on their population-based case-control study.
- In May 2001, researchers at the U.K.'s University of Nottingham reported that apple eaters had better lung function and lower risk of respiratory disease, such as asthma, than non-apple eaters.
- At the same time, researchers at the University of Groningen in the Netherlands reported that smokers eating moderate amounts of fruits and vegetables - and particularly apples - cut their risk of developing COPD nearly in half.
- In January 2000, researchers at London's St. George's Hospital also documented a possible link between apples and lung function.
- Researchers at the University of Hawaii and Finland's National Public Health Institute both linked apple consumption with a reduced risk of lung cancer in separate studies published in 2000 and in 1997, respectively.
Source: USApple. The U.S. Apple Association (USApple) is the national trade association representing all segments of the apple industry. Members include 40 state and regional apple associations representing the 7,500 apple growers throughout the country, as well as more than 400 individual firms involved in the apple business. USApple's mission is to provide the means for all segments of the U.S. apple industry to join in appropriate collective efforts to profitably produce and market apples and apple products.