infant allergy
Sarah Coe Lisa Miles
Research Assistant Senior Nutrition Scientist
British Nutrition Foundation British Nutrition Foundation
Sarah Coe graduated from the University of Surrey with a degree Lisa Miles is a Senior Nutrition Scientist at the BNF. Lisa responds
in Nutrition. She now works as a Research Assistant for the BNF, to nutrition enquiries from the media and has appeared in the
supporting the team of nutrition scientists on a variety of projects. national press and on TV and radio.
The risk of infant allergy – an update on the science
Food allergy is emerging as a major consumer and public health concern. Many people perceive that food allergy is increas-
ing in the UK in line with a general rise in allergic diseases, such as asthma and eczema. Yet, a disparity between diagnosed and
perceived allergy remains: in 2000, it was suggested that although around 20-30 percent of the population think they have a food
allergy or an adverse reaction to food, the prevalence of adverse reactions to foods and food ingredients was only 1.4-1.8% (1).
It is well known that food allergy is more common in chil- require prior exposure and sensitisation of the immune system
dren, especially those under the age of three, than in adults. to the allergen. Because peanut allergic infants tend to show
The prevalence of adverse reaction to food and food ingre- symptoms on their first known exposure to peanut, it has been
dients has been estimated to be up to eight percent in infants suggested that sensitisation to peanut is acquired by the foe-
and young children (1, 2). The most common food allergens tus during pregnancy, or by an unrecognised dietary expo-
are listed in Box 1 and these must be labelled on pre-packed sure or by non-oral (skin or respiratory) routes. For this reason,
foods sold in the UK, if included as an ingredient. As well as whether exposure to peanut in early life (maternal exposure
the ingredients list, many food products have a statement or in pregnancy or dietary exposure in infancy) is linked to a
an allergy advice box on the label stating that they contain a greater risk of childhood peanut allergy is a question that has
particular ingredient, such as gluten or milk. There might also been addressed by scientific research in this area.
be a picture of the ingredient, but this type of statement is
not compulsory on food labels and so it is always important to Government recommendations
check the ingredients list too. In August 2009 the Government issued new advice about
eating peanuts during pregnancy, breastfeeding and the first
Common food allergens; these must be clearly
few years of life, in relation to the risk of developing peanut
labelled on pre-packed foods sold in the UK allergy in childhood. The revised advice is an update of
• peanuts • fish
previous advice issued by the Committee on Toxicity (COT) in
• nuts (almonds, hazelnuts, • sesame seeds 1998 (5), which was precautionary: and targeted at moth-
walnuts, Brazil nuts, cashews, • cereals containing gluten (inc.
ers of children with a family history of allergic diseases. Such
pecans, pistachios, maca- wheat, rye, barley and oats)
damia nuts and Queensland • soya
women were recommended to avoid consuming peanuts
nuts) • lupin
and peanut products during pregnancy, breastfeeding; and
• eggs • celery for their children to avoid peanuts until three years of age.
• milk • mustard
Unfortunately, we know that the previous advice was not well
• crustaceans (including • sulphur dioxide/sulphites (preser-
prawns, crab and lobster) vatives used in some foods and
communicated. Many women and children with a family
• mollusc (including squid, mus- drinks) at levels above 10mg
history of allergic diseases did not necessarily take up the ad-
sels, cockles, whelks and snails) per kg or per litre vice and many women and children not in the target group,
followed advice to avoid peanuts unnecessarily (3,6).
Reactions to food vary considerably in the severity of the
associated symptoms and the length of time for which they
A systematic review of the latest evidence
persist. Cows' milk intolerance may be severe in early life, but
To investigate the status of the science since 1998, the
typically disappears as the child grows older. The majority
British Nutrition Foundation was commissioned by the Food
(about 90 percent) have outgrown the intolerance by the
Standards Agency (FSA) to complete a systematic review on
time they go to school (typically by the age of three years).
food allergy. The review covered a wide range of food aller-
Similarly, egg intolerance is usually a temporary phenomenon
gies including cows’ milk, eggs, fish and nuts, as well as pea-
associated with early childhood. It is, however, unclear why
nut allergy. In 1998, laboratory studies of umbilical cord blood
most childhood allergies disappear after 12-24 months whilst
showed that immune cells could be sensitised to peanut –this
others are present for life. Peanut allergy is often a life-long af-
was the main science that was used as a basis for the 1998
fliction and can cause severe, even life-threatening, anaphy-
advice. Since then, the science in this area has become
lactic reactions to tiny amounts of peanut protein.
dominated by human studies and studies on cord blood are
thought to be less relevant.
Peanut allergy Although a large number of studies were identified in the
Peanut allergy receives attention in the media because full systematic review on food allergy, just seven human stud-
very small amounts can trigger severe, sometimes fatal, al- ies reported on maternal or childhood exposure to food and
lergic reactions in susceptible people. As many as one in 55 either food sensitisation or allergy. Several of the studies found
children in the UK show evidence of an allergic reaction to were also not of a high quality. Nevertheless, the available
peanut (3); and peanut allergy is the most common cause of evidence does not indicate that either maternal exposure, or
severe allergic reaction to foods (4). Therefore, both consum- early or delayed introduction of allergenic foods in the diets of
ers and health professionals need good evidence-based ad- children, impacts upon subsequent development of food sen-
vice on whether the risk of peanut allergy can be decreased. sitisation or allergy. This lack of an effect is evident irrespective
True IgE-mediated allergic reactions such as peanut allergy of whether the child or mother has a family history of allergy.
NHDmag.com Mar '10 - issue 52 15
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