Allergies Modern life and me.

Narrated by Amanda Redman, this programme investigates the claim that changes to bacteria in the human gut is responsible for increasing the number of people with allergies. One in three people in the UK suffer from hypersensitivity disorders such as eczema, asthma and hay fever. The programme follows two allergic families with to discover how the western lifestyle may be influencing the bacteria in their bodies. Syed Hasan Arshad from the University of Southampton has studied the allergic health of UK residents for the past twenty years, during which time rates of asthma have increased tenfold. Studies have shown that the spike is specific to the western world, with immigrants’ risk of developing allergies rising threefold after having lived in a developed country for ten years. Immunologist Graham Rook believes that modern living is to blame, as it separates us from microbes occurring in the natural environment. To test the theory, the families take swab samples from their bodies and throughout their homes. The results are examined by microbiologist Lindsay Hall using gene-sequencing technology to determine the bacterial species living in each of them. The idea isn’t new; 25 years ago the ‘hygiene hypothesis’ suggested that improved levels of cleanliness reduced children’s exposure to infections and thus deprived their immune systems of the training necessary to resist allergies. For Rook, the theory is flawed; allergy is commoner in cities where rates of childhood infection are highest. He believes a broader range of microorganisms are involved; ancient microbes that supply the data needed for an appropriate immune response. The families meet with Hall to discuss the results. The allergic children, Joe and Morgan, had lower levels of bacterial diversity than their parents and siblings. Their levels of one specific type, acinetobacter – which has been associated with allergy-protection – were particularly low. In Lausanne, researchers have created ‘germ free mice’ which are more prone to allergy. The first year of life and even the moment of birth are critical, as bacterial colonies found in the vagina help to protect the newborn against allergies. But 25 per cent of babies are now born by caesarean in the UK; their bodies are more commonly colonised with bacteria found on hospital surfaces. Another threat to microbial diversity is the use of antibiotics. One study found that babies who had received a course of antibiotics in their first year of life had a 40 per cent greater chance of developing eczema. Joe, who has asthma, was born by caesarean and spent the first few days of life on an intensive care ward. At the Wellcome Library, Rook examines Medical Officer of Health reports dating from 1848-1972. They show the prevalence of what he terms ‘old infections’, such as parasitic worms and tuberculosis. Parasites must be tolerated by their hosts to survive, he explains, and consequentially suppress the immune system to allergens in the environment. Gastroenterologist Fergus Shanahan explains that diet may be one way of improving bacterial diversity without resorting to parasitic infestation, but stresses that probiotics cannot ‘cure’ allergies. Another option is the faecal transplant; replenishing gut bacteria with a healthy donor stool. Sally Bloomfield from the London School of Hygiene and Tropical Medicine explains that while maintaining basic hygiene (such as hand washing) is important, exposure to healthy bacteria can be gleaned from the environment. GPS monitors worn by the families demonstrated how little time western residents typically spend outdoors.