Why are we carrying out this study?
The principle reason for undertaking this study is to see whether the early introduction of allergenic foods into the infant’s diet can prevent the development of food allergies in children. We also wish to determine whether the other main allergic conditions - specifically asthma, eczema and hay fever - can be prevented by this approach also. The burden of these conditions falls most heavily on the paediatric (child) population. Food allergy is the most common cause of anaphylaxis outside a hospital setting. It can be fatal and it can erode or inhibit normal formative experiences in childhood. Food allergy together with eczema, asthma and hay fever significantly impact on a child’s quality of life, may cause school absence and have been shown to impair school performance.
These conditions also impose a significant burden on the NHS and can continue on into adult life with 2% of UK adults being affected by immediate type food allergies. Direct NHS costs for managing allergic problems are estimated at over one billion pounds per annum. Reducing the burden of food allergy by only 10% would amount to preventing 3600 children developing food allergy each year.
Food allergy
Food allergy develops in approximately 6% of children in the UK and there is evidence to suggest that the prevalence for particular foods like peanut has increased in recent years. Whilst the majority of children outgrow allergies to certain foods (cow’s milk and egg), for other allergenic foods, such as peanut and fish, the allergy is more likely to be lifelong. With no cure at present, people allergic to these foods must take extraordinary precautions to avoid all traces of the food.
The reason for the increase in food allergy remains unclear but it has coincided with a reduction in early introduction of complementary foods. This increase in food allergy has not been seen in some other countries. For example, there are countries in Asia, Africa and the Middle East where peanuts are a regular part of an infant’s diet and yet peanut allergy is diagnosed far less often than in the UK, strengthening support for the hypothesis that the early introduction of allergenic foods may decrease the risk of food allergy.
Duration of exclusive breastfeeding in the UK
Whilst the current UK government weaning recommendations are to exclusively breastfeed for around six months we know that in reality few mothers achieve this target. The government has produced the following figures from its 2005 national Infant Feeding Survey:
Prevalence (%) of exclusive breastfeeding by country (2005)
| England | Wales | Scotland | N Ireland | UK | |
|---|---|---|---|---|---|
| Birth | 66 | 58 | 61 | 55 | 65 |
| 1 week | 46 | 38 | 42 | 35 | 45 |
| 2 weeks | 39 | 32 | 37 | 31 | 38 |
| 3 weeks | 34 | 28 | 32 | 25 | 33 |
| 4 weeks | 29 | 21 | 25 | 20 | 28 |
| 6 weeks | 22 | 15 | 19 | 13 | 21 |
| 2 months (8 weeks) | 18 | 12 | 17 | 11 | 18 |
| 3 months (13 weeks) | 14 | 9 | 12 | 8 | 13 |
| 4 months (17 weeks) | 8 | 4 | 6 | 4 | 7 |
| 5 months (21 weeks) | 3 | 2 | 3 | 2 | 3 |
| 6 months (26 weeks) | <1 | <1 | <1 | <1 | <1 |
We will encourage all mothers participating in the EAT study to breastfeed for at least 6 months. The Standard Introduction Group will be supported to try and comply with the target of around six months exclusive breastfeeding.
Age at introduction of solids in the UK
The UK government recommends that solids are not introduced before four months of age. However we know from the government’s own Infant Feeding Survey that 51% of infants were reported to have received solid foods before 4 months of age. This figure is consistent with the average age of introduction of solids in the Millennium Cohort Study (a study in the UK of 15,980 infants) which was 3.8 months.
One reason put forward for not introducing solids before six months is concern about an increased risk of gastrointestinal infections. However, the Millennium cohort has recently reported (Quigley, 2008) that the age of introduction of solids had no effect on risk of hospitalization for diarrhoea or lower respiratory tract infection.
Why is the Early Introduction Group introducing the intervention foods before 6 months?
We believe that the window of opportunity to prevent food allergies developing may be very early in life. Emerging information from the LEAP study reveals that infants are sensitized to foods that can cause allergies far earlier than previously realized. 10% of infants under 6 months of age who were otherwise eligible to participate in the LEAP study, had to be rejected as they were already too significantly sensitized to peanut.
Despite none of the infants ever having eaten peanut before joining the LEAP study, 40% of the 4 month olds already have antibodies against peanut present in their blood.
What is special about this study?
There have been no previous studies of this kind looking at the effect of timing of introduction of allergenic foods in general. The Evelina Children’s Hospital at St Thomas’ Hospital houses a purpose-built, six-bed paediatric allergy clinical trials unit where study assessments will take place. This unit forms part of the UK Medical Research Council and Asthma UK Centre in Allergic Mechanisms of Asthma, the first disease-specific centre of its kind in the UK to investigate how and why allergy occurs. As a result, the EAT Study will be carried out within a team of doctors, nurses, dieticians and research staff with extensive expertise in the field of childhood allergies.
Who oversees the ethical conduct of the study?
The EAT Study has ethical approval from the St Thomas’ Hospital Research Ethics Committee (Reference: 08/H0802/93) and local research and development approval from Guy’s and St Thomas’ Foundation NHS Trust (Reference: RJ1 08/0282).
The study is overseen by a Trial Steering Committee which has an independent chair (Professor Graham Roberts) and an Independent Data Monitoring Committee who have both reviewed the study protocol to ensure it meets high levels of safety and ethical standards.