- Food intolerance
Food intolerance or food sensitivity is a negative reaction to a
foodthat may or may not be related to the immune systemor to food poisoning. It can be caused by the absence of specific chemicals or enzymes needed to digesta food substance, or to the body's responses to certain food constituents (chemicals) both natural or artificial.
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 immunoglobulinIgE 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 intoleranceis a result of the body not producing enough lactaseused to break down the lactosein milk. Gluten intoleranceresults in damage to villiin 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 salicylatesor 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 SyndromeCFS/CFIDS, Myalgic EncephalomyelitisME, Post-Viral Fatigue SyndromePVFS 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, migraineheadaches, and an unproductive cough.
cite journal |author=Allen DH, Van Nunen S, Loblay R, Clarke L, Swain A |title=Adverse reactions to foods |journal=Med. J. Aust. |volume=141 |issue=5 Suppl | pages=S37–42 |year=1984 |pmid=6482784 |doi=] cite journal |author=Ortolani C, Pastorello EA |title=Food allergies and food intolerances |journal=Best practice & research. Clinical gastroenterology |volume=20 |issue=3 |pages=467–83 |year=2006 |pmid=16782524 |doi=10.1016/j.bpg.2005.11.010] cite journal |author=Pastar Z, Lipozencić J |title=Adverse reactions to food and clinical expressions of food allergy |journal=Skinmed |volume=5 |issue=3 |pages=119–25; quiz 126–7 |year=2006 |pmid=16687980 |doi=10.1111/j.1540-9740.2006.04913.x] cite journal |author=Schnyder B, Pichler WJ |title= [Food intolerance and food allergy] |language=German |journal=Schweizerische medizinische Wochenschrift |volume=129 |issue=24 |pages=928–33 |year=1999 |pmid=10413828 |doi=] cite journal |author=Sullivan PB |title=Food allergy and food intolerance in childhood |journal=Indian journal of pediatrics |volume=66 |issue=1 Suppl |pages=S37–45 |year=1999 |pmid=11132467 |doi=] cite journal |author=Vanderhoof JA |title=Food hypersensitivity in children |journal=Current opinion in clinical nutrition and metabolic care |volume=1 |issue=5 |pages=419–22 |year=1998 |pmid=10565387 |doi=10.1097/00075197-199809000-00009] cite journal |author=Liu Z, Li N, Neu J |title=Tight junctions, leaky intestines, and pediatric diseases |journal=Acta Paediatr. |volume=94 |issue=4 |pages=386–93 |year=2005 |pmid=16092447 |doi=]
Food Intolerance (chemical sensitivity)
Reactions to chemical components of the diet are more common than true food allergies. They are caused by various organic chemicals occurring naturally in a wide variety of plant and other foods. Also, and more commonly recognised, by additives, preservatives, colourings and flavourings added to foods in preparation. Both natural and artificial ingredients may cause adverse reactions in sensitive people if consumed in sufficient amount, the degree of sensitivity varying between individuals. Reactions to natural food chemicals are more frequent and more insidious as they can be more difficult to diagnose.
Chemical intolerance can occur in individuals from both allergic and non-allergic family backgrounds. Symptoms can occur at any age either suddenly or more gradually. Sometimes a change in diet can trigger it, or as a result of virus infection, or serious illness, particularly when a sudden weight loss is observed. Reactions to drugs and environmental chemical exposure can occasionally be involved. It occurs more commonly in women and may be because of hormone differences, as many food chemicals mimic hormones. This form of food intolerance can present with symptoms affecting the skin, respiratory tract, gastrointestinal tract (GIT), central nervous system (CNS) either individually or in combination. The best recognised include urticaria, angioedema, migraine, irritable bowel syndrome. Respiratory tract symptoms can include nasal congestion, sinusitis, pharyngeal irritations and asthma. GIT symptoms include mouth ulcers, abdominal cramp,
nausea, and diarrhea. CNS symptoms can be bizarre resulting in patients being labelled neurotic or hysterical if food intolerance is not recognised, headache, lethargy, and myalgia are common but also memory loss, concentration difficulty, mental agitation, depression, dysphasia, visual disturbances, dizziness, tinnitus, autonomic disturbances, paraesthesias and neuralgias. Note these symptoms can be caused otherwise, making diagnosis difficult The most widely distributed natural food chemical capable of provoking reactions is salicylate containing foods, cross reactions with tartrazine and benzoic acid are well recognised. However it is not widely recognised that significant amounts of benzoates and salicylates occur naturally in many different foods including fruits, juices, vegetables, spices, herbs, nuts, tea, wines, and coffee. Other natural chemicals which commonly cause reactions and cross reactivity include amines, monosodium glutamate (MSG), nitrates and some anti-oxidants. Chemicals involved in aroma and flavour are often suspect.
It should be noted that classification or avoidance of foods based on botanical families bears no relationship to their chemical content and is not relevant in the management of food intolerance. Salicylate containing foods include apples, citrus fruits, strawberries, tomatoes, and wine, however reactions to chocolate, cheese, bananas, avocado, tomato and wine point to amines as the likely food chemical. Thus exclusion of single foods does not necessarily identify the chemical responsible as several chemicals can be present in a food and many are sensitive to a number of food chemicals and reaction more likely to occur when foods are eaten in combination that exceed sensitivity thresholds. Others may be more sensitive and react to tiny amounts. (Clarke L, McQueen J, and others (1996);"The Dietary Management of Food Allergy and Food Intolerance in Children and Adults". Australian Journal of Nutrition and Dietetics 53(3):89-98.) ] cite journal |author=Hodge L, Yan KY, Loblay RL |title=Assessment of food chemical intolerance in adult asthmatic subjects |journal=Thorax |volume=51 |issue=8 |pages=805–9 |year=1996 |pmid=8795668 |doi=] cite journal |author=Maintz L, Novak N |title=Histamine and histamine intolerance |journal=Am. J. Clin. Nutr. |volume=85 |issue=5 |pages=1185–96 |year=2007 |pmid=17490952 |doi=] cite journal |author=Layer P, Keller J |title= [Therapy of functional bowel disorders] |language=German |journal=Schweiz. Rundsch. Med. Prax. |volume=96 |issue=9 |pages=323–6 |year=2007 |pmid=17361633 |doi=] cite journal |author=Millichap JG, Yee MM |title=The diet factor in pediatric and adolescent migraine |journal=Pediatr. Neurol. |volume=28 |issue=1 |pages=9–15 |year=2003 |pmid=12657413 |doi=10.1016/S0887-8994(02)00466-6] cite journal |author=Parker G, Watkins T |title=Treatment-resistant depression: when antidepressant drug intolerance may indicate food intolerance |journal=The Australian and New Zealand journal of psychiatry |volume=36 |issue=2 |pages=263–5 |year=2002 |pmid=11982551 |doi=10.1046/j.1440-1614.2002.00978.x] cite journal |author=Iacono G, Bonventre S, Scalici C, "et al" |title=Food intolerance and chronic constipation: manometry and histology study |journal=European journal of gastroenterology & hepatology |volume=18 |issue=2 |pages=143–50 |year=2006 |pmid=16394795 |doi=10.1097/00042737-200602000-00006] cite journal |author=Asero R |title=Food additives intolerance: does it present as perennial rhinitis? |journal=Current opinion in allergy and clinical immunology |volume=4 |issue=1 |pages=25–9 |year=2004 |pmid=15090915 |doi=10.1097/00130832-200402000-00006] cite journal |author=Semeniuk J, Kaczmarski M |title=Gastroesophageal reflux (GER) in children and adolescents with regard to food intolerance |journal=Advances in medical sciences |volume=51 |issue= |pages=321–6 |year=2006 |pmid=17357334 |doi=]
Diagnosis Treatment and Management
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 suspectaddictions, 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.
It takes around 5 days of total abstinence to unmask a food/chemical, during the first week on an
elimination dietwithdrawal 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.(Clarke L, McQueen J, and others (1996);"The Dietary Management of Food Allergy and Food Intolerance in Children and Adults". Australian Journal of Nutrition and Dietetics 53(3):89-98.) ] cite journal |author=Jacobsen MB, Aukrust P, Kittang E, "et al" |title=Relation between food provocation and systemic immune activation in patients with food intolerance |journal=Lancet |volume=356 |issue=9227 |pages=400–1 |year=2000 |pmid=10972377 |doi=10.1016/S0140-6736(00)02536-8] cite journal |author=Kitts D, Yuan Y, Joneja J, "et al" |title=Adverse reactions to food constituents: allergy, intolerance, and autoimmunity |journal=Can. J. Physiol. Pharmacol. |volume=75 |issue=4 |pages=241–54 |year=1997 |pmid=9196849 |doi=10.1139/cjpp-75-4-241] cite journal |author=Gaby AR |title=The role of hidden food allergy/intolerance in chronic disease |journal=Alternative medicine review : a journal of clinical therapeutic |volume=3 |issue=2 |pages=90–100 |year=1998 |pmid=9577245 |doi=] cite journal |author=Drisko J, Bischoff B, Hall M, McCallum R |title=Treating irritable bowel syndrome with a food elimination diet followed by food challenge and probiotics |journal=Journal of the American College of Nutrition |volume=25 |issue=6 |pages=514–22 |year=2006 |pmid=17229899 |doi=] cite journal |author=MacDermott RP |title=Treatment of irritable bowel syndrome in outpatients with inflammatory bowel disease using a food and beverage intolerance, food and beverage avoidance diet |journal=Inflamm. Bowel Dis. |volume=13 |issue=1 |pages=91–6 |year=2007 |pmid=17206644 |doi=10.1002/ibd.20048] cite journal |author=Carroccio A, Di Prima L, Iacono G, "et al" |title=Multiple food hypersensitivity as a cause of refractory chronic constipation in adults |journal=Scand. J. Gastroenterol. |volume=41 |issue=4 |pages=498–504 |year=2006 |pmid=16635922 |doi=10.1080/00365520500367400]
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