1.7 Science and marketing of food elimination diets

Question 1

What is a food intolerance?

Answer 1

Response usually takes place in the digestive system. It occurs when food is not properly broken down in the gastrointestinal (GI) tract

Question 2

What are the symptoms of food intolerances?

Answer 2

Gas, bloating, flatulence, cramping, and diarrhoea.

Question 3

What is often responsible for food intolerance?

Answer 3

Enzyme deficiency

Question 4

What is the classification of food intolerances?

Answer 4

• Metabolic conditions such as enzyme deficiency and carbohydrates malabsorption
• Pharmacologic (chemical sensitivity) reactions to food components such as caffeine, monosodium glutamate (MSG),vaso active amines and salicylates
• Other undefined/ idiopathic reactions that include adverse reaction of artificial preservatives such as sulphites and benzoates

Question 5

What is a food allergy?

Answer 5

Food allergy is anadverse health effect arising from a specific immune responsethat occurs reproducibly on exposure to a given food.

Question 6

What are the categories of food allergies?

Answer 6

Type 1,2,3 and 4 hypersensitivity

Question 7

What is type 1 hypersensitivity?

Answer 7

Involve immunoglobulin E (IgE) antibody against soluble antigen, triggering mast cell degranulation.

Question 8

What is type 2 hypersensitivity?

Answer 8

Involve IgG and IgM antibodies directed against cellular antigens, leading to cell damage mediated by other immune system effectors.

Question 9

What is type 3 hypersensitivity?

Answer 9

Involve the interactions of IgG, IgM, and, occasionally, IgA antibodies with antigen to form immune complexes.

Question 10

What is type 4 hypersensitivity?

Answer 10

T-cell–mediated reactions that can involve tissue damage mediated by activated macrophages and cytotoxic T cells.

Question 11

What is lactose intolerance caused by?

Answer 11

Lactase deficiency, lactase non-persitence or hypolactasia

Question 12

What happens in lactose intolerance?

Answer 12

• Lactose transits undigested into the large intestine
• Gut bacteria metabolise lactose and the resulting fermentation produces gas (carbon dioxide, hydrogen and methane) which may result in flatulence, bloating and distension pain.
• The unabsorbed lactose and the fermentation products (e.g., short fatty acids) raise the osmotic pressure in the colon.
• This increases the flow of water into the lumen of the colon, causing “osmotic diarrhoea” associated with lactose intolerance.

Question 12

What happens in lactose intolerance?

Answer 12

• Lactose transits undigested into the large intestine
• Gut bacteria metabolise lactose and the resulting fermentation produces gas (carbon dioxide, hydrogen and methane) which may result in flatulence, bloating and distension pain.
• The unabsorbed lactose and the fermentation products (e.g., short fatty acids) raise the osmotic pressure in the colon.
• This increases the flow of water into the lumen of the colon, causing “osmotic diarrhoea” associated with lactose intolerance.

Question 12

What happens in lactose intolerance?

Answer 12

• Lactose transits undigested into the large intestine
• Gut bacteria metabolise lactose and the resulting fermentation produces gas (carbon dioxide, hydrogen and methane) which may result in flatulence, bloating and distension pain.
• The unabsorbed lactose and the fermentation products (e.g., short fatty acids) raise the osmotic pressure in the colon.
• This increases the flow of water into the lumen of the colon, causing “osmotic diarrhoea” associated with lactose intolerance.

Question 13

What are the types of lactose intolerance?

Answer 13

Congenital galactasia is extremely rare and results from an autosomal recessive mutation in the LCT gene causing the complete lack of lactase from birth.

Primary lactase deficiency (or non-persistence) is genetically inherited and is caused by the absence of a lactase persistence allele.

Secondary lactase deficiency is caused by damaged of the lining of the intestine where lactase is produced.

Question 14

How is lactose intolerance diagnosed?

Answer 14

Hydrogen breath test, lactose tolerance test, stool sample, therapy

Question 15

How is a hydrogen breath test conducted?

Answer 15

The patient has fasted overnight. After consuming 25-50g of liquid lactose, breath samples are taken every 15 or 30 min for up to 3 hours.
A rise in breath hydrogen (measured in parts per million, ppm) indicates that lactose was not digested.

Production of hydrogen is driven by the action of the gut bacteria. If hydrogen rises by more than 20ppm compared to the individual baseline, lactose intolerance is suspected.

Question 16

How is lactose intolerance test conducted?

Answer 16

This test measures the production of glucose that should normally occur if lactose is corrected digested and absorbed.

The patient has fasted overnight. Blood glucose levels are measured before and 30 and 60 min after consuming 50g of lactose.
If glucose does not rise, lactose intolerance is diagnosed.

A variation of this test (milk tolerance test), milk is given instead of lactose.

Question 17

How is a stool test conducted?

Answer 17

A stool sample test is usually performed in infants and young children with suspected lactose intolerance. Acidity and the presence of high levels of acetate and other short fatty acids can be a sign of lactose intolerance.

Question 18

What is an allergen?

Answer 18

An antigen that produces an abnormal immune response and resulting in antibody production.

Usually proteins, lipoproteins or glycoproteins

Question 19

What are immunoglobulins?

Answer 19

Antibodies

Question 20

What are antibodies?

Answer 20

Glycoproteins consisting of heavy and light polypeptide chains also containing carbohydrates

Question 21

What is allergic sensitisation?

Answer 21

First induction of an allergic immune response upon allergen encounter

Question 21

What is allergic sensitisation?

Answer 21

First induction of an allergic immune response upon allergen encounter

Question 22

What are the two routes of allergic sensitisation?

Answer 22

• Class 1 food allergens are oral allergens that cause sensitisation via the GI tract
• Class 2 food allergens are aeroallergens that cause sensitisation via the respiratory tract

Question 23

What is the process of sensitisation?

Answer 23

1. Allergen is taken and processed by antigen-presenting cells that present the antigen to T helper cells 2 (Th2)
2. Th2 cells are activated and release cytokines interleukin (IL)-4 and IL-13, activating B lymphocytes
3. B-cells recognise the allergen and combined with the cytokines-mediated activation resulting in the clonal expansion of B-cells and production of IgE that are specific against the particular allergen.
4. Frag,emt crystallisable regions of the IgE binds to Fc receptors present on mast cells

Question 24

What happens in the second-exposure-secondary immune response?

Answer 24

1. Allergens bind to multiple IgE molecules on mast cells, cross-linking the IgE molecules
2. The cross-linking of IgE activates the mast cells and triggers degranulation (a reaction in which the contents of the granules in the mast cell are released into the extracellular environment.)
3. Components released from granules include histamine, serotonin, and bradykinin, lipid mediators and cytokines
4. Chemical mediators released by mast cells collectively cause inflammation which leads to symptoms associated with type I hypersensitivity reactions.

Question 25

How does a food allergy manifest?

Answer 25

1. Food allergens enter the blood via the gastrointestinal tract, and symptoms develop directly at the sites of allergen contact.
2. Systemic reactions occur when allergens capable of cross-linking effector cell-bound IgE pass the barrier of the mucosa into the circulation.
3. Upon interaction with food antigens, IgE becomes cross-linked and binds to mast cells and basophils via the high-affinity receptor FcεR1. Mast cells and basophils are activated within a few minutes of IgE cross-linking, therefore this process iS called animmediate allergic reaction

Question 26

What are factors tgat contribute to the type and severity of reactions

Answer 26

the amount of ingested allergen, the stability of the allergen against digestion, and the permeability of the epithelial barrier.

Question 27

The release of what molecules in the circulation can lead to vascular collapse and anaphylactic shock?

Answer 27

Vasoactive mediators

Question 28

What are the roles of histamine in the allergic reaction?

Answer 28

• Stimulate mucus secretion in nasal passages and tear formation from lacrimal glands, promoting the runny nose and watery eyes of allergies.
• Cause itching and sneezing upon interaction with nerve endings
• Cause vasodilation and thus, headaches
• Cause bronchiole constriction leading to wheezing,dyspnea(difficulty breathing), coughing, etc
• Cause vomiting from stimulation of the vomiting center in the cerebellum
• Cause relaxation of intestinal smooth muscles and diarrhoea

Question 29

What molecules are late-phase reactions mediated by?

Answer 29

Eosinophils, neutrophils, and lymphocytes that have been recruited by chemotactic factors released from mast cells, in granulocyte-macrophage colony-stimulating factor.

Question 30

What is food elimination and reintroduction?

Answer 30

The UK British Dietary Association (BDA) advises individuals who suspect that they have a food intolerance to monitor their symptoms when they eat certain foods, eliminate it and then see what happens when these foods are reintroducedin the UK.

Question 31

What are the steps to food elimination and reintroduction?

Answer 31

1. Keep a food diary- details on what you eat and symptoms after eating
2. Trail elimination diet- exclude foods that cause symptoms one at a time and observe effects. Suspected food should be cut out for 2-6 weeks and see if symptoms improve
3. Reintroduction phase- try the food again to see if symptoms return

Question 32

What is the FODMAP diet?

Answer 32

Type of food elimination diet where you eliminate food that triggers IBS

Question 33

What are the types of food that trigger IBS?

Answer 33

Fermentable,Oligo-,Di-,Mono-saccharides andPolyols

Question 34

What are the three stages to the low FODMAP diet?

Answer 34

1. Restriction- avoidance of high FODMAP intake for 4-8 weeks
2. Reintroduction- if symptoms have improved with low FODMAP, reintroduce high FODMAP foods
3. Personalisation- Long-term aim of a low FODMAP diet is to personalise theirdiet so they only avoid foods that trigger theirsymptoms

Question 35

What are the commercially available tests to diagnose food intolerance?

Answer 35

• IgG blood test looks at IgG antibodies to specific foods present in a person’s blood. The test claims that an increase in IgG to a certain food indicates intolerance to that food.
• Hair analysis is where a small lock of a person’s hair is sent to a laboratory, where they scan the energy fields in the hair are scanned. The results are then compared to a database
• Provocation- neutralisation testing is where food extracts are injected under a person’s skin to try and cause food related symptoms previously reported. A different dose of the food extract is then injected to ‘neutralise’ the reaction.
• The Antigen Leucocyte Cellular Antibody Test is where a person’s white blood cells are mixed with the suspected food and changes in the size of the WBCs indicates an allergy
• Electrodermal (Vega) test measures the electromagnetic conductivity in a person’s body. An offending food will show a dip in the electromagnetic conductivity.