What are Food allergy and Food intolerance

Many people assign their variety of symptoms to food, and many such victims are seen and started on exclusion diets. The scientific proof that food does damage in most instances is feeble, although unfavorable reactions to food definitely exist. These can be classified into those that involve immune mechanisms as “food allergy” and those that do not involve immune mechanism as “food intolerance”.


Food allergy

Food allergy affect up to about 5% of young children and about 1-2% of adults. This form of allergy may be IgE mediated or non-IgE mediated (T-cell mediated). The IgE mediated reactions occurs within minutes or hour after the ingestion of the food . Adults are more likely to be allergic to fish, shellfish and peanuts, while young children are mostly allergic to cow's milk, egg white, wheat, and soy. Peanuts are very allergenic and when it is there it persists throughout life. The following conditions can result from food allergy


Acute hypersensitivity: After ingestion of nuts, strawberries or shellfish the patient suffers from urticaria , vomiting and diarrhea. These normally don’t pose much problem as the patients are aware and learn to avoid the suspected food. Unintentional eating of the incriminating foodstuff can sometimes occur, leading to angioneurotic oedema, a life threatening condition.

Eczema and asthma: Mostly IgE mediated and affect the children.

Rhinitis and asthma: In the atopic individuals these are mostly produced by milk and chocolates.

Chronic urticaria: Exclusion of particular food releive the problem in most patients

Food-sensitive enteropathy: Coeliac disease (gluten (wheat) sensitive enteropathy), and cow's milk enteropathy (in infants) are the example of this reaction.


Food intolerance

Migraine: Intake of foods like chocolate, cheese and alcohol Some patients suffer from migraine. These foods are rich in certain amines, such as tyramine, which are responsible for such attacks. Those on monoamine oxidase inhibitors, which are involved in the metabolism of these amines, are particularly susceptible.

Irritable bowel syndrome: Though mechanism not clearly understood, certain food precipitates the attack of IBS following ingestion of certain food items, such as wheat.

Chinese restaurant syndrome: dizziness, faintness, nausea, sweating and chest pains may follow after ingestion of Chinese food in some. The responsible agent is Monosodium glutamate, a flavoring agent used in cooking Chinese food.

Lactose intolerance: Abdominal bloating and diarrhea following intake of milk is probably the commonest form of food intolerance all over the world. Lactose present in the milk is the causative factor. This may be genetic in origin

Phenylketonuria: This is also a type of food intolerance, and is due to missing phenylalanine hydroxylase, which is essential for the metabolism of phenylalanine in the protein of the diet

There are other genetic errors of metabolism, which can be regarded as forms of food intolerance.

Food intolerance can occur:

To any constituent of food like the histamine in mackerel or canned food, or the tyramine in cheese.

Or,

Chemical mediators released by food stuff like histamine may be released by tomatoes or strawberries.

Or,

Toxic chemicals present in food like the food additive tartrazine.

Though sometimes thought, there are no evidence to prove that conditions such as arthritis, behavior and affective disorders and Crohn's disease are because of certain type of food ingestion. Multiple vague symptoms such as tiredness or malaise as sometimes blamed are not due to food allergy. Mostly, these patients are victim of some form of psychiatric disorder.


Treatment of food allergies and intolerance:

A careful history may help to outline the contributory mediator, particularly when the effects are instant.

Skin-prick testing with allergen, measurement of antigen or antibodies in the do not correlate with the symptoms and results are usually misleading. 'Fringe' techniques like hair analysis, has negligible value, though advised widely.

Diagnostic exclusion diets are useful but very time-consuming. They can sporadically be of value in recognizing a particular food causing allergy or intolerance.

Dietary challenge is a method where food and the test being given sublingually or by inhalation in an attempt to reproduce the symptoms. Again this may be helpful in small number of cases.

Most people who have acute allergies to food identify it and stop taking the food, and do not usually require medical treatment. In rest of the patients, a small number seem to be helped by modifying their diet, but there is no good scientific substantiation to prove these exclusion diets.

Irritable bowel syndrome (IBS) – Symptoms, Diagnosis and Treatment

IBS is the commonest Functional Gastro Intestinal Disorder. Female sufferers outnumber male counterpart. Reasons for this include the fact that anxiety and depression scores are higher in women than in men and the gut may be more sensitive to various stimuli in women. It is likely that men and women perceive internal events in the abdomen differently and that women may be more focused on these events. Food and eating are of more special psychological significance for women, as evidenced by a much higher incidence of eating disorders in women. The whole pelvic region carries a more specific significance for women, being associated not only with defecation, urination and sexuality but additionally with menstruation, pregnancy and childbirth.

IBS - a multisystem disorder

IBS patients suffer from a number of non-intestinal symptoms as stated below. The non-intestinal symptoms of IBS can be more intrusive than the classical features of IBS. IBS coexists with chronic fatigue syndrome, fibromyalgia and temporomandibular (Jaw joint) joint dysfunction


Gynaecological symptoms
Painful periods (dysmenorrhoea)
Pain following sexual intercourse (dyspareunia)
Premenstrual tension

Urinary symptoms
Frequency
Urgency
Passing urine at night (nocturia)
Incomplete emptying of bladder

Other symptoms
Back pain
Headaches
Bad breath, unpleasant taste in the mouth
Poor sleeping
Fatigue

Infectious diarrhoea precedes the onset of IBS symptoms in 7-30% of patients. Whether this is a factor for all patients or just a small subgroup remains controversial. Risk factors in these patients have been shown to include female gender, severity and duration of diarrhoea, pre-existing life events and high hypochondriacal anxiety and neurotic scores at the time of the initial illness.

Symptoms of anxiety and depression are more common in IBS patients and stress or life events often precedes the onset of chronic bowel symptoms.

Factors which are known to trigger IBS


Gastrointestinal infection
Antibiotic therapy
Pelvic surgery
Psychological stress
Psychological trauma
Sexual, physical, verbal abuse
Mood disturbances
Anxiety, depression
Eating disorders
Food intolerance


Diagnostic criteria (Rome II 1999)

These criteria state that, in the preceding 12 months there should be at least 12 weeks (consecutive) of abdominal discomfort or pain that has two of three of the following features:

Relieved with defecation; and/or onset associated with a change in frequency of stool; and/ or onset associated with a change in form(appearance) of stool.

The following symptoms cumulatively support the diagnosis of IBS:

#abnormal stool frequency ('abnormal' may be defined as > 3/day and <>
#abnormal stool form (lumpy/hard or loose/watery stool)
#abnormal stool passage (straining, urgency, or feeling of incomplete evacuation)
#passage of mucus
#bloating or feeling of abdominal distension.

These symptoms can be used to sub classify patients into diarrhoea- and constipation-predominant forms of IBS. In practice a third subgroup of alternating IBS exists, in which constipation and diarrhoea alternate. The three forms have equal frequency. Many patients with constipation have abdominal discomfort or pain with bloating or distension so there is considerable overlap with constipation-predominant IBS. The decision as to whether to investigate and if so what choice of investigations is required should be based on clinical judgement. Pointers to the need for thorough investigation are the presence of the above symptoms in association with rectal bleeding, nocturnal pain, fever and weight loss. Treatment Current strategies for treatment of IBS are based on the biopsychosocial conceptualization of IBS with targeting of central and end-organ therapies. End organ and central approaches to treatment should not be mutually exclusive and can be used in sequence and in combinations. Hydroxytryptamine (HT3)-receptor antagonists for diarrhea predominant IBS, HT4-receptor agonists for constipation predominant IBS as well as kappa opioid agonists for use in patients in whom visceral hyperalgesia plays a predominant role in the pathogenesis of their symptoms may become available.

These are the plan of management of IBS

Explore dietary triggers - Refer to dietician

High-fibre diet ± fibre supplements for constipation - Refer to dietician ± prescribe ispaghula husk

Anti-diarrhoeal drugs for bowel frequency – Loperamide, Codeine phosphate, Co-phenotrope

Smooth muscle relaxants for pain - Mebeverine hydrochloride, Dicycloverine hydrochloride, Peppermint oil


Central treatment consists of - Physiological explanation of symptoms, Psychotherapy, Hypnotherapy, Cognitive behavioural therapy and Antidepressant drug therapy