Being hypersensitive to a substance is not an allergy
Many people still believe that an adverse reaction to a substance – often a type of food – is an allergy. For example, someone who repeatedly suffers an upset stomach the day after eating cheese may say he or she is allergic to cheese, when in fact the problem is actually ‘hypersensitivity (also referred to as intolerance) to cheese. The confusion between the terms allergy and hypersensitivity is still largely in evidence. An allergy is actually limited to the most severe of several grades of hypersensitivity reactions and symptoms occur immediately after contact with the allergen, unlike the lower grades of reaction caused by a slow build-up of a problem substance. When a more delayed reaction takes place, the terms we should be using are hypersensitivity or intolerance, rather than allergy.
Food intolerance is always a threat to people who fail to eat a varied diet, for after repeated consumption of a particular food, the body becomes ‘sensitized’ to it. The result is symptoms ranging from food cravings and stomach irritations (bloating, abdominal cramps and perhaps diarrhoea) to indigestion – all of which are undoubtedly unpleasant. An increasing amount of evidence is prompting experts to believe that irritable bowel syndrome (IBS) develops as a result of food intolerance.
The foods most likely to cause intolerance problems are wheat, corn, food colourings, coffee, yeasts, citrus and dairy products, as well as foods containing chemical additives and preservatives (all processed foods, in effect).
The early stage of a true allergic reaction
In virtually any kind of war, innocent bystanders are affected – and hay fever is no different. The allergic reaction in hay fever gives rise to casualties in special cells called mast cells, an injured one of which will immediately release into the bloodstream a cocktail of inflammatory chemicals which includes histamine, tryptase, chymase, kinins and heparin. Before long, additional chemicals such as leukotrienes and prostaglandin D2 flood the bloodstream, interact with the earlier ones and, within minutes, give rise to irritation, itching, swelling and leakage of fluid from the cells, in the form of sneezing, a runny nose and watering eyes.
The late stage of reaction
Within four to eight hours, the above-mentioned chemicals have worked hard to recruit further inflammatory substances, and this results in ongoing inflammation, often extending to wider-ranging mucous membranes. The symptoms produced are similar to those of the early stage, except that there is less itching and sneezing and an increase in congestion and the creation of mucus. The mixture of chemicals can even lead to muscle spasm, which causes tightening in the lungs and throat, such as is present in asthma and laryngitis.
Fatigue, insomnia, irritability and a general feeling of malaise can arise from the late stage of reaction. Accompanying these can be ultra-sensitivity to bright light and loud noise, together with a lowered pain threshold. This invariably has a negative impact on quality of life, at least for the duration of symptoms.