Food allergy and intolerance

Adverse reaction to food may result from food aversion, intolerance or immune-mediated reactions.

Food allergy is characterized by a specific immune-mediated reaction related to ingestion of food. It is not related to physiological effects of food.

Food intolerance is not immune-mediated ; rather it is an abnormal reaction to food, e.g. lactose intolerance.

Non-immune adverse reactions to food include intolerance to lactose, jitteriness due to caffeine, toxic reaction to fish poisoning. There may also be psychological distaste or loathing for certain foods.

Although 20% of adults complain of some form of food allergy, objective confirmation by double blind food challenge studies suggest that to be true only in a small minority of population (1.4%).

One study showed that 28% of kids report food allergy, although only 8% can be confirmed by objective testing. Most of these were due to sensitivity to cow's milk. Over one third of kids with atopic dermatitis or eczema have food allergies.

After cow's milk, the commonest food allergies in kids include eggs (2.6% in kids below 2.5 years) and pea-nuts (0.4-0.6% in kids below 18 years of age).

The prevalence of food allergies appears to be increasing worldwide.. The prevalence of peanut allergy has doubled over the last 20 years. In addition, the severity and the multiplicity of food allergies appears to be rising.

This rise in food allergies may be explained by the hygiene hypothesis, i.e. lack of infectious stimuli during early growth period leads to lack of environmental education and dysregulation of immune system.

Symptoms of immune mediated food allergy can include urticaria, flushing, difficulty breathing, rash, abdominal pain, vomiting, diarrhea, intestinal bleeding, low blood pressure etc. Death may occur in severe cases.

Allergy skin tests for foods are positive in about 40-50% cases, but are not recommended for routine use. Negative skin prick tests have predictive value of 95% while positive tests must be evaluated further since their predictive value is only 45-50% without a specific history. IgE ImmunoCAP blood tests may be valuable for decision to re-challenge. While false positives occur frequently, false negative tests results are uncommon.

It should be noted that the presence of IgG to foreign proteins is not abnormal and does NOT diagnose food allergy.

In case of severe allergic reaction in kids, think of milk, egg and peanuts. In contrast, peanuts, tree nuts and shell fish account for large number of cases among adults.

Nutritional counseling plays an important role in treatment of IgE or immune mediated food allergy. Of course, any acute reaction needs to be treated if and when it occurs.

Always keep epinephrine handy and go to the nearest emergency room. Some experts recommend that in addition to epinephrine, the patient should always have an histamine-1 blocker, histamine-2 blocker drug as well as prednisone for immediate use.

Non IgE mediated food allergy may be evaluated by elimination diet, complete blood count, endoscopic biospy to exclude eosinophilic gastroenteritis. Skin tests for delayed hypersensitivity (intradermal tests and patch tests) are not useful for broad application.

Do you or someone you know has food allergy or intolerance? What measures have you taken to combat this problem? Please share your thoughts.

Comments

[NaturalAllergyRelief]

If you have a food allergy avoidance is the best cure but do not forget to replace the nutrients you will be missing. Milk contains a lot of calcium which kids need and must be found in other sources if they have a milk allergy

[murat]

Good article. I learnt useful information about food intolerance

Thanks