Change in physiological and biochemical parameters under ...
Lecture 2 Food Intolerance Biochemical and Physiological Reactions
Transcript of Lecture 2 Food Intolerance Biochemical and Physiological Reactions
Food IntolerancesFood IntolerancesBiochemical and Biochemical and
Physiological ReactionsPhysiological Reactions
2
Characteristics of Food IntolerancesCharacteristics of Food Intolerances
Non-immunologically-mediated reactionsNon-immunologically-mediated reactions May be a result of:May be a result of:
Enzyme deficienciesEnzyme deficiencies MalabsorptionMalabsorption Many mechanisms imperfectly Many mechanisms imperfectly
understoodunderstood
3
Characteristics of Food IntolerancesCharacteristics of Food Intolerances
Dose-related:Dose-related: Individual limit of toleranceIndividual limit of tolerance As quantity exceeds this, symptoms As quantity exceeds this, symptoms
increase in incidence and severityincrease in incidence and severity
4
Carbohydrate IntoleranceCarbohydrate Intolerance
Patients complain of abdominal fullness, bloating, Patients complain of abdominal fullness, bloating, and cramping within 5-30 minutes after ingesting and cramping within 5-30 minutes after ingesting carbohydratecarbohydrate
Watery diarrhoea occurs from 5 minutes to 5 Watery diarrhoea occurs from 5 minutes to 5 hours after ingestionhours after ingestion
Occasionally vomitingOccasionally vomiting Excoriation of perianal skin and buttocks due to Excoriation of perianal skin and buttocks due to
acid (pH less than 6) stool in babies and childrenacid (pH less than 6) stool in babies and children Adults do not usually experience such a low stool Adults do not usually experience such a low stool
pHpH
5
Carbohydrate Intolerance:Carbohydrate Intolerance: Causes of Intestinal Symptoms Causes of Intestinal Symptoms
Non-hydrolysed carbohydrates (polysaccharides, Non-hydrolysed carbohydrates (polysaccharides, oligosaccharides and disaccharides) pass into the large oligosaccharides and disaccharides) pass into the large intestine causing:intestine causing: Osmotic imbalance: induces a net fluid secretion into the Osmotic imbalance: induces a net fluid secretion into the
gut lumen resulting in loose stoolgut lumen resulting in loose stool Increased bacterial fermentation resulting in production of:Increased bacterial fermentation resulting in production of:
Organic acids (acetic, lactic, butyric, propionic) Organic acids (acetic, lactic, butyric, propionic) increase osmotic imbalanceincrease osmotic imbalance
Gases such as carbon dioxide and hydrogen Gases such as carbon dioxide and hydrogen cause bloating and flatulencecause bloating and flatulence
6
Carbohydrate Intolerance:Carbohydrate Intolerance: Causes of Intestinal Symptoms Causes of Intestinal Symptoms
Increased bulk results in increased stool Increased bulk results in increased stool volumevolume
Increased fluid and acid environment stimulate Increased fluid and acid environment stimulate intestinal motility and accelerate intestinal intestinal motility and accelerate intestinal transit time. transit time.
Increased speed of intestinal transit results in:Increased speed of intestinal transit results in: loose stool since fluid is not absorbed from loose stool since fluid is not absorbed from
foodfood secondary malabsorption of fatsecondary malabsorption of fat
7
Disaccharidase DeficiencyDisaccharidase Deficiency Carbohydrates are broken down by digestive enzymes Carbohydrates are broken down by digestive enzymes
to oligosaccharides and finally disaccharidesto oligosaccharides and finally disaccharides Disaccharides are broken down by disaccharidases Disaccharides are broken down by disaccharidases
produced by brush border cells in the small intestine produced by brush border cells in the small intestine to monosaccharidesto monosaccharides
Monosaccharides are absorbed by active transport or Monosaccharides are absorbed by active transport or facilitated diffusionfacilitated diffusion
Deficiency in disaccharidases results in Deficiency in disaccharidases results in malabsorption of disaccharide which passes into large malabsorption of disaccharide which passes into large bowelbowel
Symptoms result from:Symptoms result from: Changes in osmotic pressureChanges in osmotic pressure Fermentation by micro-organismsFermentation by micro-organisms
8
Lactose IntoleranceLactose Intolerance Due to lactase deficiency Due to lactase deficiency Lactase splits lactose into monosaccharides:Lactase splits lactose into monosaccharides:
GlucoseGlucose GalactoseGalactose
Monosaccharides absorbed by active transportMonosaccharides absorbed by active transport Undigested lactose moves into colon:Undigested lactose moves into colon:
Change in osmotic pressure Change in osmotic pressure Provides substrate for microbial fermentationProvides substrate for microbial fermentation
Results in Results in Excess fluidExcess fluid Organic acidsOrganic acids Gases including hydrogenGases including hydrogen
9
Types of Lactose IntoleranceTypes of Lactose IntoleranceThree types of lactose intolerance:Three types of lactose intolerance:1.1. Congenital alactasiaCongenital alactasia
Present from birthPresent from birth2.2. Idiopathic lactase deficiencyIdiopathic lactase deficiency
Natural attrition after infancyNatural attrition after infancy Affects about 80% of the world’s adult populationAffects about 80% of the world’s adult population
3.3. Secondary lactase deficiencySecondary lactase deficiency Results from damage to the lactase-producing Results from damage to the lactase-producing
brush border cells, often as a result of intestinal brush border cells, often as a result of intestinal infectioninfection
Usually temporary condition that resolves once the Usually temporary condition that resolves once the infection of intestinal damage resolvesinfection of intestinal damage resolves
10
Tests for Lactose IntoleranceTests for Lactose IntoleranceTests require ingestion of lactose: usually 50 gm Tests require ingestion of lactose: usually 50 gm
lactose powderlactose powder Hydrogen breath test: positive >20 ppmHydrogen breath test: positive >20 ppm Blood glucose or galactose levels: increase indicates Blood glucose or galactose levels: increase indicates
negative testnegative test Reducing substance in stool: presence indicates Reducing substance in stool: presence indicates
positive test (Fehlings solution changes colour from positive test (Fehlings solution changes colour from blue to red)blue to red)
Fecal pH: low pH indicates lactose fermentation and Fecal pH: low pH indicates lactose fermentation and hence positive testhence positive test
11
Management of Lactose Management of Lactose IntoleranceIntolerance
Only the milk sugar, lactose, needs to be avoidedOnly the milk sugar, lactose, needs to be avoided Milk proteins are toleratedMilk proteins are tolerated Lactose occurs in the whey (liquid) fraction of milkLactose occurs in the whey (liquid) fraction of milk Milk products free from lactose and free from whey Milk products free from lactose and free from whey
are safeare safe These foods include:These foods include:
Milk treated with lactase (LactaidMilk treated with lactase (Lactaid; Lacteeze; Lacteeze)) Hard cheeses (whey is removed; casein remains and is Hard cheeses (whey is removed; casein remains and is
fermented to form cheese)fermented to form cheese) Many people tolerate yogurt, where lactose is broken Many people tolerate yogurt, where lactose is broken
down by bacterial enzymesdown by bacterial enzymes
12
Sucrase-Isomaltase DeficiencySucrase-Isomaltase Deficiency
Primary deficiency is rare: it is inherited as Primary deficiency is rare: it is inherited as an autosomal recessive genean autosomal recessive gene
Greenland and Canadian Inuit have an Greenland and Canadian Inuit have an unusual incidence of 10% of the populationunusual incidence of 10% of the population
Appears when sucrose enters the child’s Appears when sucrose enters the child’s diet, usually when fruit juice is introduceddiet, usually when fruit juice is introduced
Severity of symptoms depends on the Severity of symptoms depends on the quantity of sucrose in the dietquantity of sucrose in the diet
Management: Avoidance of all sources of Management: Avoidance of all sources of sucrosesucrose
13
Fructose Fructose IntoleranceIntolerance Fructose intolerance is an inability to absorb free Fructose intolerance is an inability to absorb free
fructose fructose Intestinal fructose absorption depends on a low-Intestinal fructose absorption depends on a low-
affinity transporter molecule, GLUT2 that will carry affinity transporter molecule, GLUT2 that will carry the monosaccharides glucose, fructose and galactose the monosaccharides glucose, fructose and galactose across the small intestine epithelium. across the small intestine epithelium.
This carrier mechanism is facilitated by glucose, This carrier mechanism is facilitated by glucose, which permits lower concentrations of glucose to be which permits lower concentrations of glucose to be taken up by the cell by an active processtaken up by the cell by an active process
14
Fructose IntoleranceFructose Intolerance Glucose is preferentially absorbedGlucose is preferentially absorbed An excess of fructose will result in inefficient An excess of fructose will result in inefficient
absorption of the fructoseabsorption of the fructose The unabsorbed fructose moves into the large bowel The unabsorbed fructose moves into the large bowel
where it causes:where it causes: An increase in osmotic pressureAn increase in osmotic pressure Net influx or reduced outflow of waterNet influx or reduced outflow of water Acts as a substrate for microbial fermentation with Acts as a substrate for microbial fermentation with
production of gas (especially hydrogen) and organic acidsproduction of gas (especially hydrogen) and organic acids Resulting in loose stool or frank diarrhoeaResulting in loose stool or frank diarrhoea
15
Fructose Intolerance:Fructose Intolerance:The Problem FoodsThe Problem Foods
It is usually only necessary to avoid the foods It is usually only necessary to avoid the foods that contain considerably more fructose than that contain considerably more fructose than glucose These foods include:glucose These foods include: AppleApple PearPear CherryCherry BlackcurrantBlackcurrant WatermelonWatermelon HoneyHoney High fructose corn syrupHigh fructose corn syrup Agave syrupAgave syrup
16
Pharmacologic Agents in FoodsPharmacologic Agents in Foods Vasoactive amines:Vasoactive amines:
HistamineHistamine TyramineTyramine PhenylethylaminePhenylethylamine OctopamineOctopamine SerotoninSerotonin
MethylxanthinesMethylxanthines CaffeineCaffeine TheobromineTheobromine TheophyllineTheophylline
17
Pharmacologic Agents in FoodsPharmacologic Agents in Foods
Pharmacologic properties may be expressed in Pharmacologic properties may be expressed in two ways:two ways: Chemical reacts directly with body tissue in Chemical reacts directly with body tissue in
a dose-dependent fashiona dose-dependent fashion Chemical reacts with a mediator system that Chemical reacts with a mediator system that
acts on the body tissueacts on the body tissue
18
HistamineHistamine
Histamine-mediated reactions may be Histamine-mediated reactions may be clinically indistinguishable from food clinically indistinguishable from food allergyallergy
Histamine sensitivity is becoming Histamine sensitivity is becoming recognized as a disease entity quite distinct recognized as a disease entity quite distinct from allergyfrom allergy
““Idiopathic” urticaria and angioedema is an Idiopathic” urticaria and angioedema is an example of histamine sensitivityexample of histamine sensitivity
19
Symptoms of Histamine ExcessSymptoms of Histamine Excess
Vasodilatation Vasodilatation FlushingFlushing ReddeningReddening
Hypotension:Hypotension: Tachycardia (Increased heart rate)Tachycardia (Increased heart rate)
Increased vascular permeabilityIncreased vascular permeability urticaria (hives)urticaria (hives) angioedema (swelling)angioedema (swelling) rhinitis (stuffy nose)rhinitis (stuffy nose) rhinorrhea (runny nose)rhinorrhea (runny nose) otitis media (earache)otitis media (earache)
20
Symptoms of Histamine ExcessSymptoms of Histamine Excesscontinuedcontinued
Pruritus (itching)Pruritus (itching) Increase in gastric secretionsIncrease in gastric secretions
HeartburnHeartburn RefluxReflux
Headache; usually not migraineHeadache; usually not migraine Symptoms of anxiety; panic attackSymptoms of anxiety; panic attack Rarely momentary loss of consciousnessRarely momentary loss of consciousness Fatigue; listlessnessFatigue; listlessness ConfusionConfusion
21
Other Effects of Histamine ExcessOther Effects of Histamine Excess
Increase in incidence and severity of Increase in incidence and severity of anaphylactic reactionsanaphylactic reactions
Increase in incidence and severity of Increase in incidence and severity of eczemaeczema
22
Mechanism of Histamine SensitivityMechanism of Histamine Sensitivity
Excess histamine is controlled by two Excess histamine is controlled by two enzyme systems: enzyme systems: Histamine N-methyltransferase (HMT)Histamine N-methyltransferase (HMT) Diamine oxidase (DAO)Diamine oxidase (DAO)
Normally DAO rapidly degrades histamine Normally DAO rapidly degrades histamine to its inactive metabolites (imidazole to its inactive metabolites (imidazole compounds) which are excreted in urinecompounds) which are excreted in urine
HMT prevents prolonged binding of HMT prevents prolonged binding of histamine to its receptorshistamine to its receptors
Prevents histamine-induced symptomsPrevents histamine-induced symptoms
23
Mechanism of Histamine SensitivityMechanism of Histamine Sensitivity
Symptoms develop when:Symptoms develop when: Excessive amounts of histamine exceed Excessive amounts of histamine exceed
the enzymes’ capacity to break it downthe enzymes’ capacity to break it down There is a lowered enzyme capacity for There is a lowered enzyme capacity for
histamine breakdownhistamine breakdown Drugs inhibit enzyme action (e.g. Drugs inhibit enzyme action (e.g.
isoniazid)isoniazid)
24
Sites of Diamine Oxidase ProductionSites of Diamine Oxidase Production
DAO produced in various tissues, especially:DAO produced in various tissues, especially: JejunumJejunum IleumIleum KidneyKidney ThymusThymus PlacentaPlacenta
Many women experience relief of symptoms Many women experience relief of symptoms of allergy and histamine sensitivity during of allergy and histamine sensitivity during pregnancypregnancy
25
Sources of Histamine in FoodsSources of Histamine in Foods
Histidine can be decarboxylated to histamine Histidine can be decarboxylated to histamine by intestinal bacteriaby intestinal bacteria
May develop in fish that have been May develop in fish that have been improperly processed and refrigerated, improperly processed and refrigerated, especially:especially:
TunaTuna MackerelMackerel BonitoBonito BluefishBluefish Mahi mahi]Mahi mahi]
In shellfish, where intestine is not removedIn shellfish, where intestine is not removed
26
Sources of Histamine in FoodsSources of Histamine in Foods
Histamine is produced by microbial action in Histamine is produced by microbial action in manufacture of foods such as:manufacture of foods such as: CheeseCheese Fermented meats and sausagesFermented meats and sausages WineWine BeersBeers VinegarVinegar Yeast extractYeast extract SauerkrautSauerkraut
27
Sources of Histamine in FoodsSources of Histamine in Foods
Some foods contain high levels of histamine Some foods contain high levels of histamine naturally, especially:naturally, especially:
SpinachSpinach AubergineAubergine
Plant foods may produce histamine during the Plant foods may produce histamine during the ripening process, for exampleripening process, for example
TomatoTomato CherriesCherries
28
Sources of Histamine in FoodsSources of Histamine in Foods
Some foods may release histamine by a Some foods may release histamine by a non-immunologically mediated mechanism non-immunologically mediated mechanism which is presently unknown. Such foods which is presently unknown. Such foods include:include:
Egg white Egg white StrawberryStrawberry Alcohol (ethanol)Alcohol (ethanol) Citrus fruitsCitrus fruits
29
Other Sources of HistamineOther Sources of Histamine
Compounds that release histamineCompounds that release histamine:: Food additives, especially:Food additives, especially:
BenzoatesBenzoates Tartrazine and other azo dyesTartrazine and other azo dyes SulphitesSulphites
30
Other Extrinsic Sources of HistamineOther Extrinsic Sources of Histamine
Microbial flora of the large bowel includes Microbial flora of the large bowel includes species that synthesise histidine species that synthesise histidine decarboxylasedecarboxylase
Microbial enzymes act on food residue Microbial enzymes act on food residue forming histamineforming histamine
If diamine oxidase (DAO) in the gut is If diamine oxidase (DAO) in the gut is deficient, histamine is absorbed into deficient, histamine is absorbed into circulationcirculation
When there is normal DAO activity only When there is normal DAO activity only 1% of extrinsic histamine enters circulation1% of extrinsic histamine enters circulation
31
Tyramine sensitivityTyramine sensitivity Symptoms:Symptoms:
UrticariaUrticaria Migraine headachesMigraine headaches Sharp rise in blood pressureSharp rise in blood pressure
Due toDue to:: Vasoconstriction induced by dietary tyramineVasoconstriction induced by dietary tyramine
Directly because of lack of tyramine breakdown in Directly because of lack of tyramine breakdown in the intestine, liver, or arterial walls the intestine, liver, or arterial walls
Indirectly via secretion of epinephrine or Indirectly via secretion of epinephrine or norepinephrine, which is normally kept at norepinephrine, which is normally kept at unreactive levels by MAO-Aunreactive levels by MAO-A
32
Tyramine Sensitivity:Tyramine Sensitivity: Characteristics Characteristics
Mechanism of actionMechanism of action:: Low levels of monoamine oxidase Low levels of monoamine oxidase (MAO-A and MOA-B) enzymes(MAO-A and MOA-B) enzymes
Causes of low MAOsCauses of low MAOs:: Genetic predispositionGenetic predisposition Monoamine oxidase inhibiting drugs (e.g. Monoamine oxidase inhibiting drugs (e.g.
antidepressants such as Parnate; Nardil)antidepressants such as Parnate; Nardil)
33
Tyramine in FoodsTyramine in Foods
Formed by microbial action in food Formed by microbial action in food preparation, especiallypreparation, especially:: CheeseCheese WineWine YeastYeast VinegarVinegar
34
Tyramine in FoodsTyramine in Foods
Small amounts occur naturally in Small amounts occur naturally in some foodssome foods:: Chicken liverChicken liver AvocadoAvocado BananaBanana PlumPlum TomatoTomato AubergineAubergine
35
Sensitivity to Food AdditivesSensitivity to Food Additives
Characteristics common to persons sensitive to Characteristics common to persons sensitive to food additives:food additives: History of asthma and rhinitis - sometimes with History of asthma and rhinitis - sometimes with
urticaria and angioedemaurticaria and angioedema Aspirin sensitiveAspirin sensitive
36
Additives Most Frequently Causing Additives Most Frequently Causing IntolerancesIntolerances
Tartrazine (and other artificial colors)Tartrazine (and other artificial colors) SulphitesSulphites Preservatives:Preservatives:
BenzoatesBenzoates SorbatesSorbates
Monosodium glutamate (MSG)Monosodium glutamate (MSG) Nitrates and nitritesNitrates and nitrites
37
Symptoms of Tartrazine SensitivitySymptoms of Tartrazine Sensitivity
AsthmaAsthma UrticariaUrticaria AngioedemaAngioedema NauseaNausea Migraine headachesMigraine headaches Some evidence of neurological Some evidence of neurological
and behavioural reactionsand behavioural reactions
38
Postulated mechanisms to explainPostulated mechanisms to explain Tartrazine Sensitivity Tartrazine Sensitivity
Inhibition of the cyclo-oxygenase Inhibition of the cyclo-oxygenase pathway of arachidonic acid pathway of arachidonic acid breakdown. breakdown.
Histamine release from mast cellsHistamine release from mast cells
39
Allergic Response:Allergic Response:Secondary Mediator ReleaseSecondary Mediator Release
Arachidonic acidArachidonic acid
Lipoxygenase
LEUKOTRIENES
LTA4
LTB4LTC4
LTD4
LTE4
Cyclo-oxygenase
PROSTAGLANDINS (PG2)
PROSTACYCLIN (PGI2)
THROMBOXANE (TX)
40
Foods Frequently Containing TartrazineFoods Frequently Containing Tartrazine
Soft drinksSoft drinks Liqueurs and cordialsLiqueurs and cordials Sweets and confectionerySweets and confectionery Ready-to-eat cerealsReady-to-eat cereals Jams and jelliesJams and jellies Ice cream, sherbet, milk shakesIce cream, sherbet, milk shakes Commercial gravies and soup mixesCommercial gravies and soup mixes Flavor packetsFlavor packets Pickles, relish, salad dressingsPickles, relish, salad dressings Prepared baked goodsPrepared baked goods Smoked fish and fish productsSmoked fish and fish products
41
Foods Frequently Containing Foods Frequently Containing TartrazineTartrazine
Snack foodsSnack foods Meal replacementsMeal replacements Any food containing “artificial color” may contain Any food containing “artificial color” may contain
tartrazine unless it is labeled “tartrazine free”tartrazine unless it is labeled “tartrazine free”
Non-food items:Non-food items: Medications (prescription and OTC)Medications (prescription and OTC) Vitamin and mineral supplementsVitamin and mineral supplements Toiletries and cosmeticsToiletries and cosmetics
42
Sulphite SensitivitySulphite Sensitivity Most common in asthmaticsMost common in asthmatics Steroid-dependent asthmatics are most at riskSteroid-dependent asthmatics are most at risk Adverse reactions to sulphites is estimated to be as high as Adverse reactions to sulphites is estimated to be as high as
1% of the U.S. population1% of the U.S. population Sulphite sensitivity in non-asthmatics is considered to be Sulphite sensitivity in non-asthmatics is considered to be
quite rarequite rare Symptoms occur in most organ systems:Symptoms occur in most organ systems:
LungsLungs Gastrointestinal tractGastrointestinal tract Skin and mucous membranesSkin and mucous membranes Life-threatening anaphylactic reactions in asthmatics Life-threatening anaphylactic reactions in asthmatics
have been recorded, but occur very rarely.have been recorded, but occur very rarely.
43
Symptoms Reported in Sulphite SensitivitySymptoms Reported in Sulphite Sensitivity
Severe respiratory reactions: bronchospasm; Severe respiratory reactions: bronchospasm; wheezing; “chest tightness”wheezing; “chest tightness”
Asthma in asthmaticsAsthma in asthmatics Flushing; “change in body temperature”Flushing; “change in body temperature” Hypotension (drop in blood pressure)Hypotension (drop in blood pressure) Gastrointestinal symptoms (abdominal pain, Gastrointestinal symptoms (abdominal pain,
diarrhea, nausea, vomiting)diarrhea, nausea, vomiting) Swallowing difficultySwallowing difficulty Dizziness; loss of consciousnessDizziness; loss of consciousness
44
Symptoms Reported in Sulphite SensitivitySymptoms Reported in Sulphite Sensitivity
Urticaria (hives)Urticaria (hives) Angioedema (swelling, especially of the Angioedema (swelling, especially of the
mouth and face)mouth and face) Contact dermatitisContact dermatitis Anaphylaxis (in asthmatics)Anaphylaxis (in asthmatics) Anaphylactoid reaction (non-asthmatics)Anaphylactoid reaction (non-asthmatics)
45
Postulated Mechanisms to Explain Sulphite Postulated Mechanisms to Explain Sulphite SensitivitySensitivity
1.1. Sulphur dioxide is formed from sulphuric acid when the Sulphur dioxide is formed from sulphuric acid when the sulphite dissolvessulphite dissolves
Acts as a direct irritant on hypersensitive airwaysActs as a direct irritant on hypersensitive airways
2.2. Sulphite acts as a hapten, combines with a body protein to Sulphite acts as a hapten, combines with a body protein to form a neoantigen that elicits antigen-specific IgEform a neoantigen that elicits antigen-specific IgE
Results in Type I hypersensitivity reactionResults in Type I hypersensitivity reaction
3. Enzyme deficiency3. Enzyme deficiency:: Deficiency of sulphite oxidase system which converts Deficiency of sulphite oxidase system which converts
sulphite to the inert sulfatesulphite to the inert sulfate
46
Forms of Sulphites Permitted in Foods in Forms of Sulphites Permitted in Foods in the UKthe UK
E220 E220 Sulphur dioxideSulphur dioxide E221 E221 Sodium sulphiteSodium sulphite E222 E222 Sodium hydrogen sulphiteSodium hydrogen sulphite E223 E223 Sodium metabisulphiteSodium metabisulphite E224 E224 Potassium metabisulphitePotassium metabisulphite E226 E226 Calcium sulphiteCalcium sulphite E227 E227 Calcium hydrogen sulphiteCalcium hydrogen sulphite E228 E228 Potassium hydrogen sulphitePotassium hydrogen sulphite E150b E150b Caustic sulphite caramelCaustic sulphite caramel E150d E150d Sulphite ammonia caramelSulphite ammonia caramel
47
Sulphites Permitted in FoodsSulphites Permitted in Foods EU food labelling rules require pre-packed EU food labelling rules require pre-packed
food sold in the UK to show clearly on the food sold in the UK to show clearly on the label if it contains sulphur dioxide or label if it contains sulphur dioxide or sulphites at levels above 10mg per kg or sulphites at levels above 10mg per kg or 10mg per litre (or if one of its ingredients 10mg per litre (or if one of its ingredients contains it)contains it)
Non-pre-packaged foods (e.g. 'loose' foods Non-pre-packaged foods (e.g. 'loose' foods or foods prepared on the premises, or foods prepared on the premises, including take-aways and restaurant food) including take-aways and restaurant food) are not covered by this labelling are not covered by this labelling requirement requirement
48
Sulphite SensitivitySulphite Sensitivity Exposure to sulphiting agents poses very Exposure to sulphiting agents poses very
little risk for individuals who are not little risk for individuals who are not sensitive to sulphitessensitive to sulphites
There is no evidence that avoiding all There is no evidence that avoiding all sources of dietary sulphites improves sources of dietary sulphites improves asthmaasthma
Sulphates do not cause the same adverse Sulphates do not cause the same adverse reactions as sulphites. They are inert in the reactions as sulphites. They are inert in the body and need not be avoided by people body and need not be avoided by people who are sensitive to sulphiteswho are sensitive to sulphites
49
Sulphite SensitivitySulphite Sensitivity
Sulphites in foods are not denatured by Sulphites in foods are not denatured by cooking cooking
Sulphites avidly bind to several Sulphites avidly bind to several substances in foods, such as protein, substances in foods, such as protein, starch, and sugars. starch, and sugars.
Sulphites cannot be removed by washingSulphites cannot be removed by washing
50
Benzoate Intolerance Benzoate Intolerance SymptomsSymptoms
Reported to induce:Reported to induce: UrticariaUrticaria AngioedemaAngioedema AsthmaAsthma RhinitisRhinitis Purpura (allergic vasculitis)Purpura (allergic vasculitis)
51
Benzoates and Parabens:Benzoates and Parabens:Use in FoodsUse in Foods
One of the most commonly used food additives One of the most commonly used food additives worldwideworldwide
Benzoic acid and sodium benzoate (benzoates) are Benzoic acid and sodium benzoate (benzoates) are used as antibacterial and antimycotic agents in used as antibacterial and antimycotic agents in foods and beveragesfoods and beverages
Benzoates are most effective as preserving agents Benzoates are most effective as preserving agents at an acidic pHat an acidic pH
Benzoyl peroxide is used as a bleaching agent, Benzoyl peroxide is used as a bleaching agent, especially in white flour, white bread, and some especially in white flour, white bread, and some white Italian cheeseswhite Italian cheeses
52
Benzoates Benzoates Naturally occurringNaturally occurring
Benzoates occur widely in nature as simple salts Benzoates occur widely in nature as simple salts (sodium, potassium), esters, and amides(sodium, potassium), esters, and amides
Natural benzoates are present at the highest levels Natural benzoates are present at the highest levels in:in: Cinnamon, Clove, Thyme, NutmegCinnamon, Clove, Thyme, Nutmeg PrunesPrunes Black TeaBlack Tea BerriesBerries
Especially Raspberry and CranberryEspecially Raspberry and Cranberry
53
Benzoates: Benzoates: Mechanism of IntoleranceMechanism of Intolerance
Mechanism of intolerance is unknownMechanism of intolerance is unknown Has been suggested to involve inhibition of the Has been suggested to involve inhibition of the
cyclo-oxygenase pathway since a significant number cyclo-oxygenase pathway since a significant number of benzoate sensitive people are also sensitive to of benzoate sensitive people are also sensitive to aspirinaspirin
There may be a similarity in sensitivity to:There may be a similarity in sensitivity to: Tartrazine and other azo dyesTartrazine and other azo dyes SorbatesSorbates SalicylatesSalicylates
54
Monosodium Glutamate (MSG)Monosodium Glutamate (MSG)
Flavouring common in Chinese cooking Flavouring common in Chinese cooking and increasingly used to flavour Western and increasingly used to flavour Western foodsfoods
Sensitive individuals report a variety of Sensitive individuals report a variety of symptoms that are usually classified as symptoms that are usually classified as “Chinese Restaurant Syndrome” (also “Chinese Restaurant Syndrome” (also known as Kwok’s syndrome)known as Kwok’s syndrome)
55
Most Frequently Reported Symptoms of Most Frequently Reported Symptoms of Sensitivity to Monosodium GlutamateSensitivity to Monosodium Glutamate
Headache, back of head and neckHeadache, back of head and neck Numbness of faceNumbness of face Tingling/burning of face and chestTingling/burning of face and chest Tightness in chestTightness in chest Rapid heartbeatRapid heartbeat Nausea, diarrhea, stomach acheNausea, diarrhea, stomach ache Weakness, balance problemsWeakness, balance problems ConfusionConfusion Blurred visionBlurred vision Chills, shakes, perspirationChills, shakes, perspiration Difficulty breathingDifficulty breathing Asthma in asthmaticsAsthma in asthmatics
56
MSG SensitivityMSG Sensitivity Experts are widely divided on the subject of Experts are widely divided on the subject of
MSG sensitivityMSG sensitivity One review “led to the conclusion that One review “led to the conclusion that
‘Chinese Restaurant Syndrome’ is an ‘Chinese Restaurant Syndrome’ is an anecdote applied to a variety of anecdote applied to a variety of postprandial illnesses”postprandial illnesses”
Some clinicians have estimated that the Some clinicians have estimated that the prevalence of “Chinese Restaurant prevalence of “Chinese Restaurant Syndrome” may be as high 1.8% of the Syndrome” may be as high 1.8% of the adult populationadult population
57
Proposed Mechanism of Action of Proposed Mechanism of Action of MSGMSG
MSG is the sodium salt of glutamic acidMSG is the sodium salt of glutamic acid Glutamic ions are the active ingredients in MSGGlutamic ions are the active ingredients in MSG Human plasma glutamate levels after a dose of Human plasma glutamate levels after a dose of
MSG (0.1 g/kg body weight) can increase to levels MSG (0.1 g/kg body weight) can increase to levels greater than 15 times the basal concentration rate greater than 15 times the basal concentration rate in one hourin one hour
Glutamate acts as a precursor for the Glutamate acts as a precursor for the neurotransmitter acetylcholine (as well as a neurotransmitter acetylcholine (as well as a number of other physiological chemicals in the number of other physiological chemicals in the body)body)
58
Proposed Mechanism of Action of MSG: Proposed Mechanism of Action of MSG: Acetylcholine toxicityAcetylcholine toxicity
Acetylcholine reaches toxic levels in a very short Acetylcholine reaches toxic levels in a very short period of timeperiod of time
Acts on the brain and central nervous systemActs on the brain and central nervous system Symptoms ascribed to MSG sensitivity may be Symptoms ascribed to MSG sensitivity may be
caused by excessive levels of neurotransmitters caused by excessive levels of neurotransmitters such as acetylcholinesuch as acetylcholine
However, correlation between plasma levels and However, correlation between plasma levels and symptoms has not been shownsymptoms has not been shown
59
Characteristics of MSG SensitivityCharacteristics of MSG Sensitivity
Vitamin B6 (pyridoxine) deficiency may occur in Vitamin B6 (pyridoxine) deficiency may occur in some MSG sensitive peoplesome MSG sensitive people
Alcohol may increase the rate of absorption of Alcohol may increase the rate of absorption of MSG and increase the MSG and increase the severityseverity and and rate of onsetrate of onset of of symptomssymptoms
Symptoms usually occur about 30 minutes after Symptoms usually occur about 30 minutes after eating a meal high in MSGeating a meal high in MSG
Asthma occurs 1 to 2 hours after MSG ingestion, Asthma occurs 1 to 2 hours after MSG ingestion, and even as long as 12 hours laterand even as long as 12 hours later
60
Sources of MSGSources of MSG
Present in many flavouring mixtures:Present in many flavouring mixtures:AccentAccent ZestZestGourmet powderGourmet powder GlutaveneGlutaveneGlutacylGlutacyl Chinese seasoningChinese seasoningSubuSubu VetsinVetsinAjinomotoAjinomoto Kombu extractKombu extractMei-jingMei-jing Wei-jingWei-jingRL-50RL-50Hydrolysed vegetable protein (HVP)Hydrolysed vegetable protein (HVP)Hydrolysed plant protein (HPP)Hydrolysed plant protein (HPP)““Natural flavour” (may be HVP)Natural flavour” (may be HVP)
61
Sources of MSGSources of MSG
Used as a flavouring in foods, especially in Used as a flavouring in foods, especially in Chinese cooking, in canned foods (e.g. soups), and Chinese cooking, in canned foods (e.g. soups), and restaurant mealsrestaurant meals
Some sensitive individuals will also react to Some sensitive individuals will also react to monopotassium glutamatemonopotassium glutamate
Several foods, such as tomato, mushrooms, and Several foods, such as tomato, mushrooms, and cheese contain natural glutamatescheese contain natural glutamates
62
Nitrate and Nitrite SensitivityNitrate and Nitrite Sensitivity Nitrates and nitrites are used in foods as Nitrates and nitrites are used in foods as
preservativespreservatives Particularly protective against Particularly protective against Clostridium Clostridium
botulinumbotulinum Impart flavour and color to manufactured foods, Impart flavour and color to manufactured foods,
especially meatespecially meat
SymptomsSymptoms Reports of headache in sensitive individualsReports of headache in sensitive individuals
63
Nitrates and Nitrites in FoodsNitrates and Nitrites in Foods
Labels list sodium nitrate, potassium nitrate, Labels list sodium nitrate, potassium nitrate, sodium nitrite, and potassium nitrite in sodium nitrite, and potassium nitrite in manufactured foodsmanufactured foods
Present at high levels in processed meats:Present at high levels in processed meats:
• • PepperoniPepperoni • • FrankfurtersFrankfurters
• • Hot Dog WienersHot Dog Wieners • • SalamiSalami
• • BolognaBologna • • Other Luncheon MeatsOther Luncheon Meats
• • BaconBacon • • HamHam
• • Smoked FishSmoked Fish • • Some Imported CheesesSome Imported Cheeses
64
Nitrates in Plant FoodsNitrates in Plant Foods
Nitrates occur naturally in plants: the major source Nitrates occur naturally in plants: the major source is nitrate-containing fertilizersis nitrate-containing fertilizers
Some species of plants tend to accumulate nitrates Some species of plants tend to accumulate nitrates more than others:more than others:
• • SpinachSpinach • • CeleryCelery• • BeetsBeets • • LettuceLettuce• • RadishesRadishes • • CollardsCollards• • Turnip GreensTurnip Greens • Aubergine• Aubergine