It's easy to work out what the advice should be when the science behind an issue is clear cut but much more difficult when the evidence is incomplete or contradictory – as is often the case. For example, one particularly difficult issue the Agency is seeking to address at present is what sort of dietary advice we should be giving to mothers who are concerned that their child might develop a peanut allergy.
The current Government advice is that mothers whose children have a family history of allergic diseases (asthma, eczema, food allergies etc), should avoid eating peanuts during pregnancy and breastfeeding and avoid introducing peanuts into the child’s diet before 3 years of age. This advice is precautionary and was based on the evidence available in 1998, which suggested the possibility that infants could be sensitised to peanut allergens as a result of exposure before birth or during breastfeeding.
However, there is now some emerging evidence that early dietary exposure to food allergens might be important in the development of tolerance to a food allergen. This has to be considered against confounding results from recent research conducted by the Agency that suggests that, if a child is exposed to low levels of peanut proteins in the home environment as a result of consumption of peanuts by other family members, this may be leading to peanut sensitisation, particularly if the child is not eating peanuts.
The Agency has recently commissioned a new project, which builds on a major intervention study, to look at the mechanisms behind the development of peanut allergy or tolerance. This should help us understand this issue much more clearly but will take several years to complete. We are systematically reviewing all the scientific evidence that is already published and aim to be able to reconsider what our advice should be by the end of this year. In the meantime our current precautionary advice stands.
I think this neatly illustrates the problems of determining policy in the face of incomplete and conflicting evidence. But it is also illustrates why I think working at the interface between science and public health policy is so fascinating and why I enjoy this job.