Mr. Clean and the Brawny Man May Not Be Your Best Friends, After All

A recent study gives credence to the idea that the sanitized Western world may be suffering from high rates of asthma, eczema and allergy because human immune systems need to be challenged by disease and dirt. Published online in the Scandinavian Journal of Immunology, the study compared mice and rats trapped in the wild with those raised in Duke University laboratories, and found the wild mice appear to have healthier immune systems. "This is yet another study that seems to support the 'hygiene hypothesis,'" said Michael Cabana, MD, MPH, chief of General Pediatrics at UCSF Children's Hospital. "The hygiene hypothesis suggests that early environmental factors affect the immune system's development. An immune system that has not been challenged by exposure to bacteria can be prey to certain conditions," Cabana said. Those conditions include diseases like eczema, allergies and asthma. Asthma is one of the most common chronic diseases of childhood and the most common cause of school absenteeism. It is an inflammation of the bronchial tubes that causes airway obstruction, chest tightness, coughing and wheezing. Cabana is currently involved in research to determine whether intentional exposure to bacteria can lessen or even eliminate the risk of development of asthma in high-risk populations, e.g., families with a history of asthma. A secondary goal of his research is to test the hygiene hypothesis. "To test the theory, we are intentionally stimulating the immune system with probiotics [good bacteria]," Cabana said. During the next three years, Cabana and his research team will study whether giving lactobacillus to infants whose parents have asthma can prevent the disease from developing. Probiotics are defined as micro-organisms administered in adequate amounts to confer beneficial health effects. They typically are chosen from among bacteria that normally inhabit the gastrointestinal system and are therefore known to be safe. "If you can stimulate the immune system enough, you can avoid developing conditions like asthma, but at the same time still receive the benefits of living in more hygienic environments," Cabana said. Cabana said the term "hygiene hypothesis" was coined in 1989 in an article in the British Medical Journal titled "Hay fever, hygiene, and household size," which found that children raised in environments with older children were exposed to more diseases at an earlier age and were healthier. Cabana's study, the Trial of Infant Probiotic Supplementation to Prevent Asthma, or TIPS, currently is recruiting women who are pregnant and have a history of asthma or a partner with asthma to participate in the study. To find out more about the study, call 1-866/913-TIPS, or email.