Allergies in the twenty-first century
By Seb Contreras, Sep 15 2014 10:00AM
With one in 3 of us suffering from asthma, eczema or hay fever, we could say that we’re in the middle of an allergy epidemic. Allergic diseases have risen significantly in the last 5 decades. Asthma, for example affected approximately 1% of the UK’s population in the fifties, yet today it affects close to 10%. An estimated 25-30% of people in the UK suffer from one or more allergies, including those mentioned above, as well as allergies to food and animals. In my early teens I myself developed an allergy to wasp stings (as well as an allergy to tidying my bedroom). Thankfully I grew out of the latter. Scientists around the globe are searching for the reasons why allergic diseases, something that used to be rare, are now part and parcel of our daily lives.
The reason for this allergy epidemic isn’t due to exposure to allergens, because humans have always been exposed to allergens. Neither is it due to genetics as some scientists have suggested. Whilst genetics have long been acknowledged to play a part in allergies, it takes thousands of years, not a few decades, to see such changes in our genetic makeup. Therefore it must be something in our environment (i.e. urbanisation) or lifestyle that is influencing the risk of allergies. When you consider that people living in the developing world have an incidence of allergies at levels less than 1%, there is weight to back up the theory that our environment and lifestyle are to blame. Studies also show that immigrants from the developing world, who have lived in the west for 10 years or more have a threefold increased risk of developing allergies, further supporting this theory.
But what is it in our environment or lifestyle that is causing the increase in allergies? The hygiene hypothesis first proposed in 1989, suggested that because our modern lifestyle meant improved levels of hygiene and cleanliness, children’s exposure to bacteria and viruses were reduced, therefore infections reduced, depriving the immune system of the training it needed to resist allergies, and gave birth to the idea that we’re ‘too clean’. However the experts have disproved this theory, as those urban areas where allergies are more frequent, also have higher levels of the infections that the hygiene hypothesis was referring to.
Immunologist, Professor Graham Rook has modified the hygiene hypothesis, believing it is a broad range of bacteria and microbes that are lacking from people’s lives, not childhood infections, thus predisposing us to allergies. And not because we are too clean, but because we are increasingly separated from nature, as we spend larger amounts of time indoors for both work and leisure. Even a generation ago, humans spent more of their lives outdoors, interacting with the natural world, exposing themselves to a range of microorganisms that we don’t encounter living in towns and spending our day in a car or in an office. It is suggested that because we aren’t exposed to a vast range of bacterium and microorganisms from an early age, our immune system doesn’t learn to tolerate and ignore them and so doesn’t learn what is not harmful. The immune system can then develop inappropriate responses to benign items such as eggs or dairy, where it overreacts, leading to a variety of symptoms such as itching and swelling, or in serious cases, difficulties breathing or a drop in blood pressure.
Most of the body’s bacteria are stored in the gut. In fact a healthy gut should contain more variants of microorganisms and bacteria than there are species in the Amazon, yet studies have shown that people in the developed world have a lower diversity of bacteria than in the developing world, where allergies are less common. Studies have also shown that in people with allergies, this bacterial diversity is even lower. It is this understanding that bacteria are not just a cause of food poisoning and illnesses, but a vital component needed for the functioning of the human body. Whilst it is very difficult to stop allergies once they have started, exposure to a vast array of bacteria from an early age could help prevent the development of allergies in the first place. Here are some tips that can help you and your children achieve this, without living in a cave and getting your dinner by hunting antelope on the prairies or foraging for food in the forest. The following suggestions are especially important for children, but should be practiced by adults too:
Eating plenty of fresh fruit and vegetables and avoiding processed food will help expose you to many strains of good bacteria.
Eat probiotic foods such as yoghurts and cheeses, as they can help replenish bacterial stores.
Spending time in parks, woodland and the countryside means you’ll interact with a wealth of bacteria. If you’re with children, or you're a big kid yourself, hunt for insects under rocks and encourage climbing trees.
Spend time with other animals, whether it’s house pets or farm animals. Studies have shown that allergies are much rarer in the farming community, perhaps because of the time spent with livestock. This doesn’t mean you need to buy a family pet or move to a farm, but when possible, try and spend time at the homes of those friends who do own pets.
Avoid taking antibiotics unless they are absolutely necessary. Antibiotics can decimate our bodies of our good bacteria, and whilst they remain a very important drug, it’s important they are used mindfully and only when necessary, especially in the first year of life.
Continue maintaining hygiene in the home, such as wiping down surfaces, washing your hands after using the loo and before handling food. This will help to protect you from contracting illnesses from bad bacteria.
If you are expecting a baby, consider the benefits of breastfeeding when possible. The mother passes lots of good bacteria to her baby when breastfeeding.
In summary, the problem is not that we’re too clean, rather that we’ve avoided getting dirty for too long. Humans are not plastic creatures sent from outer space, plonked onto a world to live separate from it, we grew up and evolved from this world and should continue to interact with it. Now go and climb a tree and eat an apple…