When allergies go west: beyond the hygiene hypothesis

[Guest guest]

When allergies go west.

<http://www.nature.com/nature/journal/v479/n7374_supp/full/479S2a.html>

The 'hygiene hypothesis' claims the urban 'Western' lifestyle, with its

relatively limited exposure to infectious agents during childhood, might

be behind the post-war epidemics of asthma, eczema and food allergies.

But can the explosion in allergies in the developed world really be

explained so simply? A more complicated theory is emerging.

For, while it is apparent that there is something about Western living

that increases the risk of developing allergies, research has shown that

it's not just a culture of antibacterial soaps, antibiotics and

excessive cleanliness that's to blame. There is evidence to suggest

there is more about the way children are raised — where they are raised,

what they are fed and how many siblings they have — that influences

their burgeoning immune systems. It's not just that their exposure to

microbes or potential allergens seems to be limited. Sanitary living

conditions disrupt the delicate balance between our bodies and a complex

ecology of microbes and parasites with which we co-evolved, and through

which our immune systems are balanced and regulated (see 'Gut reaction',....