‘Dust mite avoidance and diet modification’ could cut childhood asthma risk

The 24-year old ‘hygiene hypothesis’ has been put into serious doubt this week after new research has suggested this theory is purely a myth.

First proposed back in 1989, the idea behind the hygiene hypothesis is that if there is childhood exposure to allergens and certain infections, this can aid the immune system’s development and teach it to differentiate between harmful and harmless substances, and thus reducing a child’s risk of developing asthma and allergies.

However, Professor Hasan Arshad, a consultant in allergy at Southampton General Hospital, has conducted a 23-year study that may somewhat discredit this theory, finding that mothers can help to massively reduce the risk of their baby developing asthma in their first year of life by avoiding certain allergenic foods and doing their best to tackle and kill house dust mites – tiny creatures that inhabit bedding, carpets, clothing and soft furnishings. It is their waste droppings and not the mite itself that triggers an allergy. House dust mite allergy is common and has been found to be linked to asthma, eczema and allergic rhinitis.

Professor Arshad spoke on the study, commenting: “Although genetic links are arguably the most significant risk factor for asthma in children, environmental factors are the other critical component. Although this was a small study, we have found that the risk of developing asthma at some point during childhood is reduced by more than 50 per cent if we introduce control of a child’s environment.”

For the 23-year study, the researchers began to track 120 people born in 1990 and who had a family history of allergies – either both parents had asthma, or just one and a sibling.

It was discovered that 58 of the people in the study had either been breastfed or had drank low-allergy formula milk until they had reached the age of nine months. In addition, their mothers had not consumed any dairy products, eggs, soya, fish and shellfish and peanuts and tree nuts. For these same people, they had benefited from a vinyl bed cover at this young age and pesticides were also used to kill dust mites. Parents of the other 62 children were not so strict and did not adhere to the same principles.

Follow-up tests were carried out when the children had reached the ages of two, three, four, eight and 18. It was discovered that 11% of those in the prevention group had asthma by the time they had reached 18. However, more than a quarter (27%) of those exposed to possible allergens had developed asthma in the same time-frame.

Professor Arshad says: “By introducing a combined dietary and environmental avoidance strategy during the first year of life, we believe the onset of asthma can be prevented in the early years and throughout childhood up to the age of 18. Our finding of a significant reduction in asthma using the dual intervention of dust mite avoidance and diet modification is unique in terms of the comprehensive nature of the regime, the length of follow-up and the size of the effect observed.” He now says that a larger-scale study is required to see if a similar result pattern is achieved.

Asthma is becoming increasingly prevalent in Britain and around the world, with 5.4 million people receiving treatment for the condition in the UK alone and an estimated one in every 11 children. The ‘Asthma and Allergies’ section of the Medical Specialists Pharmacy website has a huge range of prescription and non-prescription medications that can help with problems such as asthma and hay fever – with the latter becoming more prominent in the coming months as March is the start of the pollen season, lasting up until November.