Hygiene Theory & Allergies

Allergies are one of the most common ailments in the Western world today. In the last few decades the frequency of this disorder has been increasing at an alarming rate. Scientists are trying to determine the cause of this increase. One theory is the Hygiene Hypothesis Theory that states it is determined by the environment in which a young child is raised.

Definition

• The Hygiene Theory that attempts to explain the increase of allergies in recent years points to a lack of exposure to harmful agents that act as a way strengthen the overall immune system.

  In a normal immune system there are a number of viral, bacterial, fungal, or parasitic elements that attack the immune system. This, in turn, acts as an aid to strengthen the immune system. In today's public health system there are a number of immunizations and a widespread use of antibiotics. This provides the immune system few attempts to attack these elements and make the immune system stronger.

Supporting Evidence

• There are several things that appear to support the idea of the Hygiene Theory could be a viable factor in the increase in allergies. First, there is a lower occurrence of allergies in rural areas, including those living on farms. This portion of the population is exposed to more bacteria.

  There is also a lower incidence of allergies of the youngest children in larger families. These children are exposed to more infections from older siblings. In addition, children who attend daycare are exposed to more infections and have a lower incidence of asthma and wheezing.

History

• The increase in allergies led scientists to investigate this troubling trend. In 1989, a report was released that showed that a lack of early repeated exposure to allergens could actually increase the risk of developing allergies. One factor that appeared to contribute to an increase in allergies was household cleanliness. The report also noted that children who had repeated exposure to allergens through older siblings had a less likely chance of developing allergies.

  The initial study was complied from a group of 17,414 British children. The children were then followed for 23 years. These initial findings encouraged more in-depth study of the Hygiene Hypothesis and it still continues more than two decades later.

Research

• Two noted researchers on food allergies, Dr. Andrew H. Liu and Dr. Scott H. Sicherer, note that the Hygiene Hypothesis carries over into the immune system of mice, as well. Mice are more allergic to food if they are raised in a germ-free environment and treated with antibiotics at a young age.

  Results from a 2006 study show that the early exposure of potential food allergens may reduce the likelihood of an allergy developing. This study showed that infants who were exposed to wheat after six months of age were four times more likely to develop an allergy to it.

Contradictions

• As with any theory, there is room for some contradictions that lead some to doubt it. In the Hygiene Theory, there is no concrete explanation of the higher rates of allergies and asthma among African American inner city children. Presumably these children are exposed to more viruses and bacteria that most children.

  It is worth noting, however, that there may be several other factor in the living condition of the poor that can have a great impact on these children that may contribute to these conditions that are completely independent of the Hygiene Theory factors.