• Question: how do we get allergic to something?

    Asked by Lorenzo to Arthur, Clare, Daniel, David, Tora on 17 Nov 2014.
    • Photo: Clare Harding

      Clare Harding answered on 17 Nov 2014:

      That’s a great question and there are a lot of people trying to work it out!

      Some people are definitely genetically more likely to get allergies than others but, in the past 50 years there has been a huge increase in the numbers of people with allergies.

      There are lots of theories on why this would happen but my favorite is the hygiene hypothesis, this is the idea that in the olden days people were exposed to lots of bacteria and especially worms that lived inside them. But since we started looking after our food and disinfecting everything, basically our immune systems get bored and start attacking harmless things like pollen or peanuts.

      This is one idea, an there are some people who have been deliberately infected with worms and it has helped with their asthma or hayfever but I don’t know if this treatment would catch on, would you do it?

    • Photo: Daniel Parsons

      Daniel Parsons answered on 17 Nov 2014:

      Super question.
      As Clare says there are lots of scientists trying to work this out right now.
      It is thought that tendency for having allergies is in our genes and it is passed down. The chances that you also will be allergic increase from about 50 percent when one parent is allergic to about 80 percent when both parents have allergies.
      Related to what Clare said, in population studies the number of people with allergies is low in developing countries, which lack the advanced sanitation found in wealthier countries. This lack of sanitation leads to an early exposure to parasites and other microbes that is likely similar to what humans have experienced over centuries of evolution. Since our immune systems evolved over long periods of time under constant exposure to microbes, if those microbes are removed, the system’s potential is still active but no longer has a suitable target….and what happens is our bodies don’t adjust well and start to overreact immune responses to harmless environmental stimulus (such as pollen).

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