Revision questions - week 4

Question 1

digestible carbohydrates

Answer 1

can be digested and therefore provide energy

Question 2

Indigestible cabrohydrates

Answer 2

(contain dietary fibre consisting of a group of complex carbohydrates (found mostly in veges, fruits and legumes) with a fibrous structure the makes them indigestible by humans so contribute no calories or energy to diet) don’t react in water

Question 3

monosaccharides

Answer 3

simplest carbohydrate
- 6 carbon single units – glucose (carbonyl group on C-1, undergoes glycolysis or glycogenesis), fructose (carbonyl group on C-2, not insulin dependent) and galactose (OH group around C-4, converted to glucose in the liver)
- 5 carbon single unit – ribose and deoxyribose
screenshot of how they look

Question 4

disaccharides

Answer 4

• Maltose – glucose to glucose, alpha 1,4 glycosidic bond, cereals
• Lactose – galactose to glucose, beta1,4 glycosidic bond, milk
• Sucrose – glucose to fructose, alpha 1,2 glycosidic bond, table sugar, fruit

Question 5

polysaccharides

Answer 5

Starch – digestible, storage form of carbohydrate in plant,
- Amylose – continuous chain of glucose molecules linked alpha 1,4 glycosidic bonds, - lower GI because broken down more slowly
- Amylopectin – branched chain of glucose molecules linked by alpha 1,4 and alpha 1,6 glycosidic bonds, enzymes can come from every angle and therefore can break down quickly
Glycogen
- Storage form of glucose, branched structure containing 1,2 an d1,6 alpha glycosidic bonds
Cellulose

Question 6

Why would fructose be considered a “good” sugar for diabetics? 


Answer 6

Because blood sugar levels only measure glucose, this false though as turns to glucose inside the cell

Question 7

What is high fructose corn syrup? How is it different to table sugar? 


Answer 7

sweeter as proportion of fructose (55) to glucose (42)

are nutritionally the same

Question 8

Why is it preferred by the food industry

Answer 8

??

Question 9

Define how amylose, amylopectin and glycogen differ from each 
other in structures (bonds, and enzymes used to digest the structures) 
 - will come back to after rewatching lecture

Answer 9

• Amylose – linked alpha 1,4 glycosidic bonds, broken down by salivary amylase
• Amylopectin – linked by alpha 1,4 (broken down by salivary amylase) and alpha 1,6 glycosidic bonds,
  Glycogen
  containing 1,4 (hydrolysed by both salivary & pancreatic
  amylase) and 1,6 alpha glycosidic bonds (intestinal α-dextrinase)

Question 10

Explain the concept of “carbohydrate quality” using the glycemic 
index and glycemic load

Answer 10

?

Question 11

What determines the degree of fermentability of indigestible carbohydrates?

Answer 11

The solubility – more soluble more fermentation

Question 12

Define dietary and functional fibre?

Answer 12

• Dietary fibre comes from food, functional fibre is added to food
• Men – 30g, women – 25g
• Endpoints chosen to estimate requirements were – adequate gastrointestinal function and adequate laxation rather than reduction of risk for chronic disease

Question 13

How are carbohydrate foods involved in BGL? 


Answer 13

glucose??

Question 14

What are the mechanisms that regulate high and low blood sugar 
levels (BGL)? 


Answer 14

??

insulin and glucagon??

Question 15

How is the quality of carbohydrate in food determined, looking at the 
NIP?

Answer 15

NIP does not show quality? Can be rated by glycaemic quality, glycemic load, carbohydrate quality

Question 16

Physiological function of fibre

Answer 16

1. Promoting bowel health by increasing faecal bulk and laxation
2. Reducing obesity and weight gain risk
3. Assisting in blood glucose control
4. Reducing plasma cholesterol
5. promoting gut health and overall health

Question 17

Promoting bowel health by increasing faecal bulk and laxation

Answer 17

• increases faecal bulk will increase the volume circulating in intestine which promotes peristalysis
• Prevention of diverticulae and diverticulosis/diverticulitis

Question 18

Reducing obesity and weight gain risk

Answer 18

Assists in appetite control: feeling fuller because it slows down gastric emptying, thus less overeating
- more bulky so slows down as feeling of still full and less likely to over eat

Question 19

Assisting in blood glucose control

Answer 19

Slowing down gastric emptying, therefore slowing down CHO digestion and glucose absorption and rise in BGL
- glucose absorbed quickly from sugar but when mixed with fibre takes longer for enzyme to access CHO to break down and enzymes will have longer time due to gastric emptying

Question 20

Reducing plasma cholesterol

Answer 20

Promotes binding and excretion of cholesterol and bile,and thus prevents reabsorption of cholesterol (discussed when studying lipid)
- if consume cholesterol (we produce 80%) and have fibre you prevent dietary cholesterol as it tends to bind with cholesterol

Question 21

Is honey a healthier option to table sugar? Why?

Answer 21

honey isnt a healthier option as contains same amount of CHO

Question 22

What is meant by lactase persistence? What is the outcome?

Answer 22

means that one has a mutation in the region of this gene (genetic adaptation);
will elimate lactose intolerance

Question 23

What is meant by alpha diversity in the context of the gut microbiota? 


Answer 23

Healthy diversity = healthy gut microbiota (richness,variety and evenness in species)

Question 24

How does diet promote health benefits through alpha diversity?

Answer 24

??

Question 25

how to calculate the glycemic load of foods

Answer 25

Multiply th eamount ofCHO by the GI value of the food divide by 100.

Question 26

the lower the GL the better if one is concerned about keeping BGL under control

Answer 26

cause with a lower GL one will not experience a spike in BGL followed by a steep drop, but rather have a gradual moderate rise after the food consumption

Question 27

someone with glycogen storage disease ___ ___need to __carbohydrate of any sort

Answer 27

does:not: need

just can’t produce glycogen efficiently or at all, which is an issue when fasting or exercising

Question 28

Why cant muscle glycogen be used for BGL

Answer 28

because the lack of glucose-6-phosphatase in the muscle

Question 29

Why is fructose associated with fatty liver?

Answer 29

because it is converted to intermediate of glycolysis very quickly and thus increases the pool of acetyl-coA quickly

Question 30

WHy is GL more accurate than GI

Answer 30

the glycemic index rates foods according to the BGL response over 2 hours after consuming 50 g of CHO in this food. The GL is more accurate because it takes into consideration how much exactly of that food is being consumed as opposed to a set 50 g standard.

Question 31

lactose intolerance

Answer 31

“default program” for human adults

Question 32

probiotics

Answer 32

foods/ supplements providing the live micro-organisms to populate the GIT adequately
e.g. yoghurt and sauerkraut

Question 33

prebiotics

Answer 33

dietary or supplemental constituents which provide substrate for bacterial fermentation and growth
e.g. jerusalem artichoke and banana

Question 34

synbiotics

Answer 34

combination of pre and prebiotics in the food /supplement

e.g. mixing e.g. banana and yoghurt

Question 35

Discuss the health benefits of meeting the fibre requirements daily, by 
detailing the mechanisms of action for these benefits
1- veronique answer

Answer 35

Good fibre intake can contribute to weight loss in individuals requiring to lose weight: it helps reduce appetite
and increase satiation because fibre slows down gastric emptying, which gives the sensation of having a full
stomach for longer. This is means that there is less chance to overeat, but more chance to eat less, resulting in weight loss

Question 36

Discuss the health benefits of meeting the fibre requirements daily, by 
detailing the mechanisms of action for these benefits
2- veronique answer

Answer 36

Good fibre intake helps in blood glucose control: by slowing down gastric emptying, the CHO are broken down
by the digestive enzymes in the duodenum gradually, resulting in more gradual glucose absorption. The access
to digestible CHO by enzymes is also more difficult because of the fibre

Question 37

Discuss the health benefits of meeting the fibre requirements daily, by 
detailing the mechanisms of action for these benefits
3- veronique answer

Answer 37

Fibre is a prebiotic, meaning that it is “food” for the gut bacteria. Gut bacteria ferment the fibre, and in the
process produce short chain fatty acids which are beneficial for the host’s health, and for the prevention of colon
cancer

Question 38

Discuss the health benefits of meeting the fibre requirements daily, by 
detailing the mechanisms of action for these benefits
4- veronique answer

Answer 38

Consuming the target amount of fibre ensure a regular bowel movement (= regular laxation), which prevent
the development of diverticular disease

Question 39

Discuss the health benefits of meeting the fibre requirements daily, by 
detailing the mechanisms of action for these benefits
5 - veronique answer

Answer 39

Consuming a good amount of fibre can reduce dietary cholesterol absorption, reducing the risk of high blood
cholesterol: some of the dietary cholesterol binds to the fibre and is being excreted.
Fibre also promotes the excretion of bile. This means that bile is not absorbed in the distal ileum. The liver will
need to make new bile, for which it will have to use plasma cholesterol, thus reducing high blood cholesterol

Question 40

promoting gut health and overall health

Answer 40

Fibre is a substrate for gut bacteria fermentation. This promotes growth and diversity of bacterial gut species. The fermentation process also produces short chain fatty acids (SCFA): acetate, butyrate, propionate. SCFA have protective effects on colonic cells (protection from colon cancer) and have a variety of health benefit for the host