A leading theory behind the rising allergy and asthma diagnosis rates is the "hygiene hypothesis." This theory suggests that living conditions in much of the world might be too clean and that kids aren't being exposed to germs that train their immune systems to tell the difference between harmless and harmful irritants.
This concept is supported by studies that show that individuals living on farms develop fewer allergic diseases. The theory is that farm animals increase exposure to germs and germ components called endotoxin. These endotoxins stimulate the immune response and decrease allergic inflammation.
Other research suggests that the rising prevalence of allergies and asthma may be more complex and the result of one or more different factors:
Antibiotics and Acetaminophen
Some research indicates that increased use of certain medications contribute to the increase in asthma. Studies have shown that increased antibiotic use parallels the rise in allergy and asthma. Researchers suggest that early antibiotic use changes the bacterial flora, which impacts the development of allergic diseases such as asthma. Other studies suggest that increased use of acetaminophen (Tylenol) in children might have an impact on the increased risk of asthma and allergies.
Obesity and Asthma
Many experts believe that lifestyle changes associated with diet and activity are leading to rising rates of chronic diseases. Increased obesity in general has been suggested as a contributing factor for the increase in asthma prevalence.
Vitamin D Deficiency and Asthma
Some experts believe rising rates of asthma may, in part, be due to a deficiency of vitamin D. Vitamin D is essential for lung and immune system development. Because children tend to spend more time indoors than in past generations, this reduces their exposure to sunlight. This results in reduced vitamin D production.
This article has been reviewed by Andrew Moore, MD, FAAAAI