Apples and Selenium May Lower Asthma Risk

Eating apples and the mineral selenium may lower one's risk of asthma, which suggests that certain antioxidants may protect the lungs from disease.

Antioxidants help neutralize damaging forms of oxygen that arise from normal metabolism.

These free radicals are unstable compounds that can damage cells and are thought to contribute to chronic disease.

Researchers surveyed nearly 1,500 UK adults about their eating habits during the previous year. They focused particularly on intakes of fruits and vegetables, flavonoid-rich foods like apples, onions, tea and red wine, antioxidant vitamins, and trace elements that act as antioxidant enzymes -- such as selenium, zinc and copper.

The investigators found that people who ate at least two apples per week faced a 22%- to 32% lower asthma risk than those who ate fewer.

And as selenium intake increased. Participants with the highest intakes -- 54 to 90 micrograms a day -- were only about half as likely to have asthma as those who consumed the least selenium, about 23 to 30 micrograms daily. The US recommended daily intake for selenium is 55 micrograms.

The researchers speculate that certain subtypes of flavonoids may be key in this protection since other flavonoid-containing foods did not affect asthma risk or severity. Or, in the case of apples, different compounds altogether may be at work.

As for selenium, they suggest that part of the blame for the UK's rising asthma rates may rest in the nation's declining selenium intake. The researchers note that selenium may protect against asthma by suppressing airway inflammation.

Selenium is found in foods such as Brazil nuts and walnuts, and beef.

American Journal of Respiratory and Critical Care Medicine 2001;164:1823-1828