Food Intolerances
Food Intolerance
Food intolerance or non-allergic food hypersensitivity is a delayed, bad reaction to say a food, drink or food additive. It can cause symptoms in one or more body organs and systems, but is not a true allergy.
Intolerance can result from the absence of specific chemicals or enzymes needed to digest a food substance, or from reactions to naturally occurring chemicals in foods.
The precise distinction between food intolerance and a food allergy is often missed. A true food allergy, it is believed, requires the presence of certain antibodies against the food. All other hypersensitivities or adverse pharmacological reactions to foods can be considered food intolerances.
Intolerance Definition
Non-allergic food hypersensitivity is the medical name for food intolerance, loosely referred to as food hypersensitivity, or previously as pseudo-allergic reactions. Non-allergic food hypersensitivity should not be confused with true food allergies.
Food intolerance reactions can include pharmacologic, metabolic, and gastro-intestinal responses to foods or food compounds. Food intolerance does not include either psychological responses or foodborne illness.
A non-allergic food hypersensitivity is an abnormal physiological response. It can be difficult to determine the poorly tolerated substance as reactions can be delayed, dose-dependant, and a particular reaction-causing compound may be found in many foods.
* Metabolic food reactions are due to inborn or acquired errors of metabolism of nutrients, such as in diabetes mellitus, lactase deficiency, phenylketonuria and favism.
* Pharmacological reactions are generally due to low-molecular-weight chemicals which occur either as natural compounds, such as salicylates and amines, or to food additives, such as preservatives, colouring, emulsifiers and taste enhancers. These chemicals are capable of causing drug-like (biochemical) side effects in susceptible individuals.
* Gastro-intestinal reactions can be due to malabsorption or other GI Tract abnormalities.
* Immunological responses are mediated by non-IgE immunoglobulins, where the immune system recognises a particular food as a foreign body.
* Toxins may either be present naturally in food, be released by bacteria, or be due to contamination of food products. Toxic food reactions are caused by the direct action of a food or substance without immune involvement.
* Psychological reactions involve manifestation of clinical symptoms caused not by food but by emotions associated with food. These symptoms do not occur when the food is given in an unrecognisable form.
Elimination diets are useful to assist in the diagnosis of food intolerance. There are specific diagnostic tests for certain food intolerances.
Prevention
There is emerging evidence from studies of cord bloods that both sensitization and the acquisition of tolerance can begin in pregnancy, however the window of main danger for sensitization to foods extends prenatally, remaining most critical during early infancy when the immune system and intestinal tract are still maturing. There is no conclusive evidence to support the restriction of dairy intake in the maternal diet during pregnancy in order to prevent. This is generally not recommended since the drawbacks in terms of loss of nutrition can out-weigh the benefits. However, further randomised, controlled trials are required to examine if dietary exclusion by lactating mothers can truly minimize risk to a significant degree and if any reduction in risk is out-weighed by deleterious impacts on maternal nutrition.
A Cochrane review has concluded feeding with a soy formula cannot be recommended for prevention of allergy or food intolerance in infants. Further research may be warranted to determine the role of soy formulas for prevention of allergy or food intolerance in infants unable to be breast fed with a strong family history of allergy or cow's milk protein intolerance. In the case of allergy and celiac disease others recommend a dietary regimen is effective in the prevention of allergic diseases in high-risk infants, particularly in early infancy regarding food allergy and eczema. The most effective dietary regimen is exclusively breastfeeding for at least 4-6 months or, in absence of breast milk, formulas with documented reduced allergenicity for at least the first 4 months, combined with avoidance of solid food and cow's milk for the first 4 months.