I.

The entire CAFA Initiative--State Coordinating Office, Regional Centers and directly funded local asthma coalitions, with support from our Partners in policy advocacy, media and evaluation-- received a USEPA "Children's Environmental Health Recognition Award."  We were also among the finalists considered for one of the few "Excellence" awards, which required the applicant's efforts covered each of the three categories (outreach/advocacy, education/awareness, interventions).  The award strongly reflects upon CAFA's initial 3.5 years, and should inspire the work local asthma coaltions will continue in future years.

Also, please see http://www.calendow.org/asthmalinks.stm for press release and related links from our primary funder, The California Endowment.  

II.

What is the connection between asthma in children and overweight and obesity?

Particularly as childhood obesity is receiving more attention, people are asking questions regarding its connections with asthma. This article summarizes peer-reviewed clinical, laboratory and human epidemiology studies conducted and published during the last decade — the different hypotheses under consideration, and what the data have helped us understand so far. Please note details were excluded, and more research is ongoing or to be conducted worldwide over the next decade. Current research has suggested associations between diagnosed asthma and overweight/obesity, though it is not yet clear whether one causes the other, or another factor predisposes a person to both diseases. Researchers have proposed several hypotheses for the correlation, which warrant further studies.

For the complete list of 27 references cited for this article, please click here.

Background

Below are several terms commonly used in scientific discussions on overweight and obesity:

• Body Mass Index (BMI) is a measure combining a person’s weight and height; researchers can use BMI to compare the relative obesity of people of varying heights.
• Overweight, obesity, and underweight are often used in comparison to a reference population. Different researchers use different definitions.
• Obesity is generally a more severe condition than overweight.
• The health consequences of underweight usually result from malnutrition.

Overweight/obesity and underweight relate more to caloric intake and body type and composition (bone density, % body fat, and % lean muscle mass) rather than nutritional status based on essential vitamins and minerals. It is not healthy to be underweight,overweight, obese, or malnourished, and each condition may be related to asthma (Schachter et al., 2001).

Summary of current research

Several studies have reported associations between obesity and asthma, the severity of asthma symptoms, and the persistence of asthma later on in life:

• Data on 3792 California school children who did not have asthma at the start of the USC “Children’s Health Study” (Gilliland et al, 2003) but later developed it suggested the risk of new-onset diagnosed asthma was statistically significantly higher among both overweight and obese children.
• In a sample of American children ages 4-17 (von Mutius et al, 2001), the prevalence of physician-diagnosed asthma, controlling for variables like tobacco smoke exposure and birth weight, was statistically significantly higher with increasing BMI.
• In a study of 1322 asthmatic children ages 4-9 in seven American cities, including two boroughs of New York City, asthmatic children who were obese had statistically significantly more emergency department visits and a higher mean number of days of wheezing per two-week period over nine months following initial, baseline health assessments (Belamarich et al, 2000).
• A study in Tucson, Arizona (Guerra et al, 2004) reported the majority of asthmatic children ages 6-16 reported their persistent wheezing continued after puberty (unremitting asthma); obesity was one statistically significant predictor variable for unremitting asthma. Another study in Arizona (Castro-Rodríguez et al, 2001) found females who were overweight or obese at age 11 were statistically significantly more likely to have current wheezing at ages 11 and 13.

Asthma and weight gain can affect anyone.
Nevertheless, due to environmental factors, there may be differences in the prevalence and severity of asthma and overweight and obesity by gender, socioeconomic status, and race/ethnicity.

• Studies worldwide have suggested overweight or obese females have a higher prevalence of diagnosed asthma and/or allergic respiratory symptoms than males (Chen et al, 1999; Huang et al, 1999; Castro-Rodríguez et al, 2001; Figueroa-Muñoz et al, 2001). Only one study has reported asthmatic boys and girls were both statistically significantly more likely to be obese (Gennuso et al, 1998).
• Studies of New York State children reported:
• The prevalence of overweight was statistically significantly higher in New York City black and Hispanic children with moderate to severe asthma as defined by school absenteeism, medications prescribed, and lung function measures (Luder et al, 1998).
• More asthmatic than non-asthmatic black and Hispanic children in Buffalo were obese (Gennuso et al, 1998).

Most popular hypotheses

The association between asthma and obesity raises a “chicken or egg” question—is the asthma causing the obesity or is the obesity causing the asthma? Researchers in the USC “Children’s Health Study” observed obesity can be present earlier in life than asthma (Gilliland et al, 2003), but this does not necessarily prove obesity causes asthma (Beckett et al., 2001). Several possible human physiological processes support each chronic disease in the roleof exposure or of disease:

• Asthma, including exercise-induced asthma, may minimize or prevent physical activity, which can lead to being overweight or obese.
• Weight gain may affect how the lungs and upper airways operate mechanically, regardless of whether a person is susceptible to allergies or has lung inflammation. For example, the USC “Children’s Health Study” documented increases in asthma among obese children who were not allergically sensitized (Gilliland et al, 2003).
  Alternatively, higher BMI (obesity) may indicate behaviors or lifestyle factors also associated with the increasing prevalence of asthma in different population groups (Chinn and Rona, 2001).
• Obesity alters levels of several hormones in a person’s body, which may affect the underlying processes of asthma development such as inflammation or allergic sensitization (Tantisira and Weiss, 2001).
• Nutritional factors and genetics likely have roles in both the development and increasing prevalence of asthma (Greene, 1999) and obesity.
• Increased intake of antioxidant vitamin C has been associated with a decreased prevalence of asthma diagnosis and/or symptoms (Harik-Khan et al, 2004; Rubin et al, 2004).
• The possible association between salt intake and diagnosed asthma and/or airway responsiveness remains inconclusive (Demissie et al, 1996).
• Some researchers have hypothesized a mother’s nutritional status during pregnancy may lead to changes in physiology or metabolism during critical periods of development of the fetus, which predispose the child to both asthma and obesity later on (Tantisira and Weiss, 2001).
• Obesity alters the usual positions of the body and the stresses placed upon it. For example, obesity alters airway positioning during sleep, so obese people may snore more. Whether obesity could also affect airway development or functioning is unknown.

Conclusion

Current research suggests associations between diagnosed asthma among young children, adolescents and adults, particularly females, and overweight/obesity defined by BMI. However, it is not yet clearlyunderstood whether one condition leads to the other, or whether a single factor predisposes a person to both conditions. Researchers have identified several possible ways asthma and obesity may be connected. Thus, this is an interesting and increasingly important area of research and public health education.