Food allergies: time to take stock
An increasing number of cases!
The prevalence of food allergies has increased by five over the past 20 years. The food environment and changes in our intestinal flora are the cause.
Food allergies affect 3.5 % of adults and 8 to 10 % of children
Although food allergies are on the increase, they should not be mistaken for intolerance reactions (e.g. gluten/lactose) or distaste.
To prove an allergic reaction, a sensitivity test should be carried out by an allergist.
The most frequently incriminated foods
The most commonly found food allergies are caused by the following :
- Gluten
- Peanuts
- Egg
- Fish and seafood
- Apricot, cherry, quince, peach, plum, olives
- Cow's milk
- Soy
- Celery, aniseed, carrot, chervil, cumin, fennel
- All by-products…
More specifically for children, the major allergens are:
- Egg (34% of cases of allergy)
- Peanuts (25 %)
- Milk (9 %)
- Fish (5 %)
- Nuts (3 %)
- Shellfish (2 %)
- Wheat (2 %)
- Kiwi (1 %)
- Mustard (1 %)
- Soy
Questions/answers on food allergies
Why are we allergic?
The digestive system has a sophisticated immunity system to defend the organism from foreign bodies passing through it. In certain people with a predisposition, this system goes well beyond its prerogatives and triggers off defensive reactions in contact with certain food allergens. The digestive wall may simply be more permeable to the passage of these allergens.
What is the difference between allergy and intolerance?
A food allergy is a reaction to a protein in the food, which involves the immune system. The passage of the allergen through the intestinal barrier causes an inflammatory reaction.
In cases of intolerance, the immunity system is not involved.
There are often cases of foods that cause a release of histamine, activating the mastocytes by a non-allergic mechanism (strawberry, egg white, chocolate, alcohol). It can also involve substances released by fish meat (e.g. mackerel, tuna, sardines) or present in matured cheese, certain fermented foods (e.g. sauerkraut, salami, tinned foods, certain wines, tuna, yeast extracts).
What are the symptoms?
A food allergy may be expressed by digestive symptoms such diarrhoea, vomiting and abdominal pain and other symptoms such as asthma, ear and nose infections and skin problems.
What are the causes?
For certain specialists, 50% of dermatological problems in babies and children (atopic dermatitis) are due to food allergies .
The introduction of certain foods too early on favours the appearance of these food allergies which can result in eczema or asthma in babies. It is very important to respect the order of introduction of foods when diversifying a baby's diet and give baby natural foods and unprocessed foods as often as possible, especially in families already showing cases of food allergy.
Is it possible to cure a food allergy?
Certain allergies evolve towards a cure:
80 to 90 % of allergies to cow's milk disappear at adulthood
50 % of cases of allergy to egg disappear around the age of 3.
20 % of allergies to peanuts are cured
Allergies to fish, seafood and mustard tend to remain.
What is the difference between an allergy to cow's milk and an intolerance to cow's milk?
The allergenicity of cow's milk is caused by its proteins, especially caseins, beta lactogobulines and alpha lactalbumines. It occurs in 0.5 to 4 % of children, but its prevalence reduces with age and usually disappears at adulthood. Although specific to each child, the most frequent symptoms are vomiting and diarrhoea.
The allergenicity of cow's milk may be reduced by different types of processing of the milk. Heat treatment alters certain proteins, thereby reducing their allergenic power. For this reason, some individuals sensitive to milk can tolerate sterilized or powdered milk, but not pasteurized milk.
The structure of proteins in fermented milks, such as yoghurt and cheese, is not modified. The products therefore remain allergenic.
Once the milk allergy diagnosis has been made, it is indispensable to ensure a balanced diet, especially during periods of growth. It is necessary to cover calcium, magnesium and vitamin A, D, B2 and B12 requirements.
Intolerance to cow's milk is due to lactose, a form of sugar. In our smaller intestine, we normally have an enzyme, called lactase, that breaks down lactose into simple sugars (glucose and galactose), which are then absorbed in the blood. When lactase activity is low, lactose is accumulated and passes into the large intestine where it is fermented by colic flora. This causes symptoms such as flatulence, pain and diarrhoea.
Generally speaking, North Europeans develop more lactase than populations in the Middle East. In reality, 70% of the world's population does not produce enough lactase and therefore suffers from various degrees of lactose intolerance. If milk is not properly digested, hard, low-lactose cheeses and fermented dairy products tend to be well tolerated. They can be used to cover nutritional intake such as calcium, without causing digestive problems.
How are allergens labelled?
The labelling of allergens is regulated by the European Directive relating to food labelling: directive 2000/13/CE modified by directive 2003/89/CE published at the end of 2003.
What are the symptoms and what are the causes?
Henceforth, all major allergens, regardless of their proportions, should be mentioned on product labelling. Certain exceptions on labelling are no longer authorized. It is therefore no longer possible to indicate the ingredient category only (e.g. "vegetable oil") and it is compulsory to indicate the precise allergen ("groundnut oil"). The source of a flavour should be indicated. It is also compulsory to indicate ingredients in the labelling of alcoholic drinks. The list of potential allergens and their derivatives to be mentioned in labelling is as follows: cereals containing gluten, shellfish, eggs, fish, peanuts, soy, milk and dairy products (including lactose), nuts, celery, mustard, sesame seeds, sulphur dioxide and sulphites in quantities in excess of , 10 mg/kg or 10 mg/l. Member states have one year in which to apply these new rules and manufacturers have an extra year to modify their labelling. The new labelling should therefore appear on products in 2005.
Links:
ALLERGO France www.abcallergie.com
AFDIAG (association Française des intolérants au gluten) www.Afdiag.org
AFPRAL (Association française pour la prévention des allergies) www.prevention-allergies.asso.fr
