Michelle Berriedale-Johnson reports

The Food Standards Agency's annual presentation focused this year on their work in the field of food allergy, not just in terms of allergen labelling but on the various research projects which they either partially or totally fund.

The keynote speech was given by Professor Ian Kimber, Professor of Toxicology at the Faculty of Life Sciences at the University of Manchester, and before discussing the individual projects Professor Kimber made a number of general points:

• Allergy is an adverse effect from an inappropriate immune response to specific proteins.
• The immune system is essential to protect us but it can turn on itself.
• Since world War II there has been a dramatic increase in allergy.
• Antibodies protect us against bacterial infection; in evolutionary perspective, IgE antibodies protect us again multicellular parasites.
• In allergy the immune system mis-recognises proteins as parasites.
• Once the immune system has been primed to mis-recognise the protein as a parasite, its reaction will escalate in severity.
• Those who are not atopic (prone to allergy) will have the antibody to the food proteins but this will not provoke an IgE allergic response.

Why has the incidence of allergy grown so fast in the last 60 years?

• Hygiene hypothesis – that, because we have become so 'clean' and hygiene obsessed our immune systems have not had a chance to learn 'tolerance' as they never encounter bacteria etc.
• Genetic susceptibility or 'atopic-ness'. 60 years is far too short time for this great a genetic change. Interestingly, although susceptibility to allergy appears to be genetically transferred it is rarely specific to a food or an allergen - what is transferred is the likelihood that the child will have allergic reactions.

Root of exposure

• Why do some children react on their first ingestion of peanut?
• Maybe because they have already been sensitised via the skin through contact with household peanut dust or peanut protein residue on parents' hands.
• But why do some children achieve tolerance and others not? Could the root of exposure be relevant?
• Jewish children in London are 10 times more peanut allergic than Jewish children in Israel yet there is no difference in the incidence of other food allergies. But, Jewish children in Israel are weaned on a peanut mush.
• So is it possible that early dietary exposure to peanut might induce tolerance while early exposure via the skin only causes sensitisation after which dietary exposure will not induce tolerance but an allergic reaction?

Conditions of exposure

• How potent is the allergen? Peanut proteins for example are very potent whereas lettuce proteins are quite weak.
• How persistent is the allergen? Peanut allergy tends to be lifelong whereas milk or egg allergies, which are no less serious when they are active, tend to be transient – they are mainly experienced in childhood and most children 'grow out of them'.
• Conditions of exposure
    - glycosolation - what effect a carbohydrate will have on a protein in terms of allergenicity
    - extrinsic factors – what effect does stress in terms of sleep deprivation, viral infection, exercise etc have on the reactivity of the allergic person eg the amount of the allergen they need to consume to have a reaction

Current FSA funded or partially funded research includes:

EAT (Enquiring about Tolerance) which is trying to discover whether the early introduction of allergenic foods alongside continued breastfeeding reduces the incidence of food allergy.

LEAP (Learning Early About Peanuts) is trying to find out whether introducing peanuts at an early age to highly atopic children at risk of peanut allergy may prevent the development of the allergy.

The BASELINE study which is trying to determine whether an abnormal skin barrier function, which may be genetically determined, can predate or predict food allergy sensitisation.

Allergy thresholds. The ongoing efforts to establish thresholds for allergenic ingredients at which the majority of seriously allergic people will not react.

Allergens in prepacked food. Surveys to establish how accurate in terms of labelling a range of foods on the market actually is.

The TRACE study is aiming to discover how much peanut is needed to cause a reaction in adults and whether this is affected by extrinsic stress factors, sleep deprivation and exercise.

Future research projects will include:

• Adult allergy. The rate of allergy amongst children over the last 30 years has been significantly higher than that among adults – but many of those children have now grown up. How had that changed the incidence of allergy in adults and indeed, the nature of the allergy.

• Food intolerance as opposed to allergy.

First published September 2013

• If this article was of interest you will find many other articles on unlikely allergies and allergy connections here – and links to many relevant research studies here.

• For more on the more 'mainstream' allergies check in to our 'allergy and intolerance home page' – and for ideas on alternative foods go here.

Back to top