Food intolerance or food sensitivity is a negative reaction to a food that may or may not be related to the immune system or to food poisoning. It can be caused by the absence of specific chemicals or enzymes needed to digest a food substance, or to the body’s responses to certain food constituents (chemicals) both natural or artificial.
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Not to be confused with food allergies, a food intolerance can cause various symptoms including bloating, abdominal pain and diarrhoea. It is an adverse reaction to some sort of food or ingredient that occurs every time the food is eaten, but particularly if larger quantities are consumed.
This isn’t the same as a food allergy, because the immune system isn’t activated. Neither is it the same as food poisoning, which is caused by toxic substances that would cause symptoms in anyone who ate the food.Food intolerance doesn’t include psychological reactions to food either.
Symptoms of food intolerance vary greatly, and can be mistaken for the symptoms of a food allergy. While true allergies are associated with fast-acting immunoglobulin IgE responses, it can be difficult to determine the offending food causing an intolerance because if the immune system is involved, the response is likely to be IgG mediated and takes place over a prolonged period of time. Thus the causative agent and the response are separated in time, and may not be obviously related. A deficiency in digestive enzymes can also cause some types of food intolerances. Lactose intolerance is a result of the body not producing enough lactase used to break down the lactose in milk. Gluten intolerance results in damage to villi in the small intestine, which makes it difficult for the body to absorb water and nutrients from foods. Another type of food intolerance is an intolerance to food chemicals such as salicylates or salicylate sensitivity. Salicylates are chemicals that can occur naturally in many foods. Salicylate sensitivity causes many symptoms the most common of which are: hives, stomach pain, head aches, mouth ulcers, and it has even been linked to ADD and ADHD.
Food intolerance can exist as a separate condition or contribute to the symptoms of complex syndromes such as Chronic Fatigue Syndrome CFS/CFIDS, Myalgic Encephalomyelitis ME, Post-Viral Fatigue Syndrome PVFS and may involve causes such as Leaky Gut Syndrome. For these reasons diagnosis is best carried out by experienced practitioners.
Symptoms of a food intolerance include gas, intermittent diarrhea, constipation, irritable bowel syndrome, skin rashes, migraine headaches, and an unproductive cough.
Food intolerances are rarely harmful but may cause unpleasant symptoms, including nausea, bloating, abdominal pain and diarrhoea, which can begin hours or days after eating or drinking the food in question.
The severity of symptoms varies depending on the amount of enzyme the person makes and how much of the food has been consumed. In alcohol intolerance, there may be intense flushing of the skin, nausea, palpitations, headache and feeling faint.
Food intolerance occurs when the body is unable to deal with a certain type of foodstuff. This is usually because the body doesn’t produce enough of the particular chemical or enzyme that’s needed for digestion of that food.
For example, one of the most common types is intolerance of cow’s milk, which contains a type of sugar called lactose. Many people have a shortage of the enzyme lactase, which is normally made by cells lining the small intestine. Without this enzyme they can’t break down milk sugar into simpler forms that can be absorbed into the bloodstream.
Lactose intolerance can cause symptoms very similar to irritable bowel syndrome.
Another common example is a deficiency of an enzyme called alcohol dehydrogenase. Drinking even small amounts of alcohol can make affected people feel unwell.
Some people have adverse reactions to chemical preservatives and additives in food and drinks, such as sulphites, benzoates, salicylates, monosodium glutamate, caffeine, aspartame and tartrazine.
The lack of a specific enzyme in the body may lead to the build up of toxic byproducts and histamine, which then mimic the symptoms of an allergy. This is called a ‘pseudo-allergic’ reaction.
There’s a strong genetic pattern to food intolerances. Lactose intolerance is less common among northern and western Europeans (10 to 15 per cent are affected) than in Asian, African, native American and Mediterranean populations (70 to 90 per cent are affected).
Babies are usually born with higher levels of lactase, so lactose intolerance usually only begins after the age of about two, as the body begins to produce less of the enzyme. But many people don’t experience symptoms until they’re much older. A temporary lactase deficiency may follow gastroenteritis, especially in children.
Alcohol intolerance is common among Asian people – 50 per cent are affected.
Diagnosis can include elimination and challenge testing, clinical investigation is generally undertaken only for more serious cases, as for minor complaints not affecting lifestyle the cure may be more inconvenient than the problem. Treatment can involve avoidance, and re-establishing a level of tolerance.
Individuals can try minor changes of diet to exclude foods causing obvious reactions, and for many this may be adequate without the need for professional assistance. For reasons mentioned above foods causing problems may not be so obvious. Persons unable to isolate foods and those more sensitive or with disabling symptoms should seek expert medical and dietitian help. The dietetic departments of teaching hospitals is a good start. (see links below)
Guidance can also be given to your general practitioner to assist in diagnosis and management. Food Elimination Diets have been designed to exclude food chemicals likely to cause reactions and foods commonly causing true allergy problems and those foods where enzyme deficiency cause symptoms. These elimination diets are not every day diets but intended to isolate problem foods and chemicals. Avoidance of foods with additives is also essential in this process.
Individuals and practitioners need to be aware that during the elimination process patients can display aspects of food addiction, masking, withdrawals, and further sensitization and intolerance. Those foods that an individual considers a ‘must have everyday’ are suspect addictions, this does include tea, coffee, chocolate and health foods and drinks, as they all contain food chemicals. Individuals are also unlikely to associate foods causing problems because of masking. Where separation of time between eating and symptoms occur. The elimination process can overcome addiction and unmask problem foods so that the patients can associate cause and effect.
Lactose intolerance can be tested for more thoroughly using a lactose tolerance test, a hydrogen breath test and a stool acidity test. Your doctor can arrange these and other food intolerance tests if necessary.
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Food intolerance can be managed simply by cutting the food out of your diet. Babies or younger children with a lactose intolerance can be given soya milk or hypoallergenic milk formula instead of cow’s milk.
It takes around 5 days of total abstinence to unmask a food/chemical, during the first week on an elimination diet withdrawal symptoms can occur but it takes at least 2 weeks to remove residual traces. If symptoms have not subsided after 6 weeks, food intolerance is unlikely involved and a normal diet should be restarted. Withdrawals are often associated with a lowering of the threshold for sensitivity which assists in challenge testing, but in this period individuals can be ultra sensitive even to food smells so care must be taken to avoid all exposures.
After 2 or more weeks if the symptoms have reduced considerably or gone for at least 5 days then challenge testing can begin. This can be carried out with selected foods containing only one food chemical, so as to isolate it if reactions occur. In some countries such as Australia purified food chemicals in capsule form are available to doctors for patient testing, these are often combined with placebo capsules for control purposes. (see link below) This type of challenge is more definitive. New challenges should only be given after 48 hours if no reactions occur. Or after 5 days of no symptoms if reactions occur.
Once all food chemicals are identified a dietitian can prescribe an appropriate diet for the individual to avoid foods with those chemicals. Lists of suitable foods are available from various hospitals and patient support groups can give local food brand advice. A dietitian will ensure adequate nutrition is achieved with safe foods and supplements if need be.
Over a period of time it is possible for individuals avoiding food chemicals to build up a level of resistance by regular exposure to small amounts in a controlled way, but care must be taken, the aim being to build up a varied diet with adequate composition.
Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose