food: nutrition and malnutrition - MD2B1

Question 1

what is the difference between a food allergy and food intolerance?

Answer 1

food intolerance is in the digestive system

food allergy involves the immune system

Question 2

what are symtoms of a food allergy?

Answer 2

> can manifest with GI symptoms
but generaally appears on the skin > (hives, itchiness, swelling)
respiratory symptoms
can induce anaphylaxis

Question 3

wht are symptoms of food intolerance?

Answer 3

unpleasant GI symtoms - gas, bloating, flatulence, cramps, diarrhoea

Question 4

what is a food allergy?

Answer 4

immune system in the GI tract protects against potential pathogens and what the body recognises as foreign

in a food allergt, the immune system identifies the food as an invasive threat

Question 5

what are the categories of food intolerance?

Answer 5

1. metabolic - enzyme deficiency, carbohydrat malabsorption

2. pharmacologic - chemical sensitivity - caffeine, MSG

Question 6

what breaks down lactose?

Answer 6

lactose

a beta galactosidase enzyme

Question 7

what is lactose broken down into?

Answer 7

glucose and galactose

Question 8

how are glucose and galactose transported into the enterocytes before moving into the blood circulation?

Answer 8

sodium/glucose transporter SGLT1

Question 9

what can lactose intolerance caused by? (3)

Answer 9

lactase deficiency
lactase non-persistence
hypolactasial

inability to digest lactose in the small intestine

Question 10

describe the pathophyisology of lactose intolerance

Answer 10

lactose transits undigesred into the large intestine
here the gut bacteria metabolise it resulting in fermentation which produces gas (CO2, H, CH4) - this cuases flatulence, bloating, distension
the unabsorbed lactose and the fermentation products (e,.g, short chain FA) raise osmotic pressure in the colon

this increases flow of water into the lumen of the colon causing osmotic diarrhoea

Question 11

what gene encodes lactase?

Answer 11

LCT gene regualted by MCM6 protein

mutations in MCM6 are assocated with keeping the LCT gene on

lactose intolerant indiviuals lack this mutation

Question 12

what is primary lactase deficiency?

Answer 12

(NON-PERSISTENCE)

genetically inherited
absence of lactase persistence allele
age-related decrease in lactse deficiency leading to hypolactasia in adulthood

Question 13

what is secondary alactaase deficiency?

Answer 13

caused by damaged lining of the intestinal wall where lactase is produced

caused by gastroenteritis, coeliac disease, IBS, medications, parasites

its transient and normally dissapearrs when the intestinal wall has recovered

Question 14

what is congenital lactase deficiency?

Answer 14

alactasia

rare, autosomal ressesive mutation in the LCT gene causing complete lack of lactase from birth

Question 15

what is the hydrogen breath test?

Answer 15

> patient is fasted overnight
consume 25-50g liquid lactose
breath samples taken every 15.20 minutes for up to 3 hrs
rise in breath hydrogen indicates lactose was not ingested
rise of more than 20ppm compared to individual baseline, lactose intolerance is suspected

Question 16

what is the lactose tolerance test?

Answer 16

> This test measures the production of glucose that should normally occur if lactose is correctly digested and absorbed
The patient is fasted overnight
Blood glucose levels are measured before and 30 and 60 mins after consuming 50G of lactose
If glucose does not rise, lactose intolerance is diagnosed
A variation of this test is the milk tolerance test – milk instead of lactose

Question 17

what is type 1 hypersensitivity?

Answer 17

involves immunoglobulin E (IgE) antibody against soluble antigen

triggers mast cell degeneration

Question 18

what is type 2 hypersensitivity?

Answer 18

involves IgG and IgM antibodies directed agaisnt cellular antigens, leading to cell damage mediated by other immune system effectos

Question 19

what is type 3 hypersensitivity?

Answer 19

interactions of IgG and IgM and occaasioanlly IgA antibodies to form immune complexes, accumulaation of immune complexes in tissues leads to tissue damage

Question 20

what is type IV hypersensitivity

Answer 20

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

Question 21

what foods are common to IgE associated food allergies?

Answer 21

milk, eggs, wheat, peanuts, sesame, fish, fruits and veg

Question 22

what factors contribute yo yhe type and severity of the reactions?

Answer 22

smouunt of ingested allergen, stability of allergen against digestion, permeability of epithelil barrier

Question 23

what is a food elimination diet?

Answer 23

monitor sympyyomd when they eat certian foods, eliminate it and then see what happens when these foods are reintroduced

Question 24

what is the FODMAP diet?

Answer 24

Type of food elimination diet looking to eliminate specific symptoms which can trigger symptoms of IBS

Question 25

what does FODMAP stand for?

Answer 25

Fermentable, Oligom Di, Monosaccharides and Polyols

Question 26

how does a FODMAP diet work?

Answer 26

Stage 1: restriction (eat low FODMAP diet and see if symptoms reside)
Stage 2: reintroduction (reintroduce slowly to see which trigger)
Stage 3: pesonalisation (long term only avoid foods that were triggering you

Question 27

what are the 4 layers of the GI tract?

Answer 27

mucosa

submucosa

muscular propria

serosa