Tag Archives: asthma

Why Do Obese People Have More Asthma?

It may be related to leptin, a hormone produced by fat cells (adipocytes).  ScienceDaily has all the details, most pertinent of which is that the study at hand was done in mice.  So not ready for prime time (humans).  Some of the sickest asthmatics I’ve cared for have been morbidly obese.

Mediterranean Diet Improves Asthma

Researchers in Portugal found that high adherence to the Mediterranean diet reduced by 78% the risk of out-of-control asthma.

Other recent studies have associated the Mediterranean diet with 1) lesser incidence of asthma-like symptoms and allergies in children of women who followed the Mediterranean diet while pregnant, and 2) reduced risk of chronic obstructive pulmonary disease in men who eat Mediterranean-style.

The Mediterranean diet is famous for prolonging life and reducing rates of cardiovascular disease, cancer, and dementia.  Type 2 diabetes mellitus was recently added to the list of diseases prevented by the Mediterranean diet.  We have to consider adding lung disease to the list next.

In my capacity as a hospitalist, I see lots of poorly-controlled asthmatics.  The standard therapeutic approach is avoidance of allergens when possible, and administration of multiple drugs with multiple potential adverse effects.  So the following study involving diet and asthma caught my eye.

Scientists in Portugal studied 174 asthmatics with an average age of 40.  They administered an Asthma Control Questionnaire and measured lung function and exhaled nitric oxide.  Food intake was determined with a food frequency questionnaire, and a diet score was used to determine conformity to the Mediterranean diet.

Asthmatics felt to be under good control comprised 23% of the participants.  Were there dietary factors associated with good control?

I’m glad you asked.  The answer is , “Yes”:

  • high adherence to the Mediterranean diet
  • higher intake of fresh fruit
  • lower intake of ethanol (alcohol)

The researchers note that “the traditional Mediterranean diet is claimed to possess antioxidant and immune-regulatory properties in several chonic diseases.  Typical Mediterranean foods have recently been associated with improvement of symptoms of asthma and rhinitis [runny nose, often allergy-related] in children” in Crete and Spain.

This study is good news for people with asthma.  But association of well-controlled asthma with the Mediterranean diet does not prove that the diet is causing the improvement.  Next, we need a study that educates people with asthma on the Mediterranean diet, monitors adherence, and follows them over time while checking for improvement in asthma and comparing to a control group on a standard diet.

Steve Parker, M.D.

Reference:  Barros, R., et al.  Adherence to the Mediterranean diet and fresh fruit intake are associated with improved asthma control.  Allergy, vol. 63 (2008): 917-923.

Does Food Affect Lung Disease?

In another blog post, I provided evidence that diet may indeed affect lung function and disease, specifically asthma.  Another common lung condition is chronic obstructive pulmonary disease (COPD), which includes chronic bronchitis and emphysema.  COPD is usually associated with smoking.

By the way, a couple years ago “chronic lower respiratory tract disease” finally surpassed stroke to become the third leading cause of death in the U.S.  These lung diseases are mostly emphysema, COPD, and asthma.

In 2007, scientists with the Harvard School of Public Health, Harvard Medical School, and Simmons College concluded that “in men, a diet rich in fruits, vegetables, and fish may reduce the risk of COPD whereas a diet rich in refined grains, cured and red meats, desserts and French fries may increase the risk of COPD.”

The Boston, MA, researchers included academic heavyweights such as Teresa Fung, Walter Willett, and Frank Hu.  They studied 42,917 men in the Health Professionals Follow-up Study via detailed periodic questionnaires.  The men at baseline had never had asthma or COPD.  Onset of COPD between  1986 and 1998 was evaluated by questionnaire and was defined as an “affirmative response to physician-diagnosed chronic bronchitis or emphysema and by the report of a diagnostic test at diagnosis (pulmonary function testing, chest [x-ray] or chest CT scanning).”  Participants reported 111 new cases of COPD.

Investigators identified two distinct major dietary patterns at baseline:

  1. “Prudent” pattern:  high intake of vegetables, fruits, fish, poultry and whole grains.
  2. “Western” pattern:  high consumption of cured and red meats, refined grains, desserts and sweets, French fries, eggs and high-fat dairy products.

The prudent dietary pattern was inversely associatied with the risk of newly diagnosed COPD, regardless of smoking status.  In other words, the higher an individual’s conformity to the prudent pattern, the lower the risk of new COPD.

On the other hand, the Western pattern was positively associated with the risk of newly diagnosed COPD, again regardless of smoking status.

They did not note any association between either dietary pattern and the risk of developing asthma.

Clearly, there are similarities between the prudent dietary pattern and the traditional Mediterranean diet.  The main differences are that the Mediterranean diet includes significant amounts of olive oil, limited red meat and eggs, and judicious amounts of wine.  The Mediterranean diet incorporates the prudent pattern.  But the Mediterranean diet is not the “prudent dietary pattern” studied at Harvard.  Whether the Mediterranean diet would match or supercede the prudent diet in prevention of COPD is a matter of speculation.  The smart money would bet in favor of the Mediterranean diet reducing rates of COPD to at least some degree.

In view of a study associating improved asthma control with the Mediterranean diet, you gotta wonder if the researchers would have confirmed it, if they had been looking.  Are there substances in olive oil, or other aspects of the Mediterranean diet, that  improve lung function?

Many people are aware that dietary patterns have an effect on heart disease, overweight and obesity, high blood pressure, diabetes, dementia, cancer, and strokes.  We can add chronic lung disease to the list now.

Steve Parker, M.D.

Reference:  Varraso, Raphaelle, et al.  Prospective study of dietary patterns and chronic obstructive pulmonary disease among US men.  Thorax, vol. 62, (2007): 786-791.