Harvard study links obesity to asthma

An asthma patient

April 26, 1998
Web posted at: 10:50 a.m. EDT (1450 GMT)

BOSTON (CNN) -- People who suffer from obesity are three times more likely to develop asthma, according to a study by Harvard Medical School.

For years, doctors have suspected a link between obesity and asthma. The presumption was always that asthma develops first, and that the respiratory limitations it causes makes it difficult for sufferers to exercise, which leads to obesity.

The Harvard study, by Dr. Carlos A. Camargo Jr., was designed to prove the theory. Instead, Camargo found that obesity develops first.

"What we found is that the heavier you are ... the more likely you are to get asthma," Camargo told CNN.

Both obesity and asthma are on the rise in developed nations. In the United States, where health officials say one in three people are obese, the rate of asthma rose 61 percent from 1982 to 1994.

An estimated 15 million U.S. citizens suffer from asthma. The condition kills an estimated 5,000 people a year.

Camargo followed 89,061 nurses between 1991 and 1995, noting their weight and height from the start of the study. Age, race, smoking and physical activity were factored into the study. Camargo found that 1,652 of the nurses developed asthma.

The findings only apply to adults. A study on a correlation between asthma and obesity in children is under way.

The study did not determine how obesity increases the risk of asthma, but Camargo speculates that excess weight compresses the airways, making them smaller and therefore more reactive to cold and other asthma triggers.

Critics say Camargo's study is useful, but that it raises more questions than it answers. More studies are needed to back up his findings, critics say.

"The explanation about compressing airways seems too simplistic," said Dr. Ronald M. Ferdman, an asthma specialist at Childrens Hospital Los Angeles.

Others in the field wondered about a possible genetic link between asthma and obesity, and suggested more data be collected about the exercise habits of asthma sufferers.

The Harvard study is the first to link obesity and asthma. The results are to be presented this week at the international conference of the American Thoracic Society and the American Lung Association to be held in Chicago.

Correspondent Elizabeth Cohen and The Associated Press contributed to this report.

CNN Community:

• Asthma and obesity

In-Depth Health:

• Asthma
• Obesity

Related sites:

Note: Pages will open in a new browser window

• Harvard Medical Web
• American Lung Association
• American Thoracic Society
• Asthma Information Center

External sites are not endorsed by CNN Interactive.

---

 

---

Sound off on our message boards & chat