Carbohydrates

Question 1

RDI carbohydrates

Answer 1

40-65% of energy needs from carbohydrates. Only 10-15% of this from free sugars.

Question 2

Name the three categories of carbohydrates

Answer 2

Monosaccharides
Disaccharides
Polysaccharides

Question 3

Examples of monosaccharides

Answer 3

Glucose, galactose, fructose

Question 4

Examples of disaccharides

Answer 4

Lactose, maltose, sucrose

Question 5

Examples of polysaccharides

Answer 5

Glycogen, starch, non-starch polysaccharides (dietary fibre)

Question 6

Describe the features of non-starch polysaccharides

Answer 6

Two categories: Soluble and non-soluble. These are not broken down into monosaccharides and thus contribute very little energy. Not digested by the small intestine

Question 7

Name complex carbohydrates and food sources)

Answer 7

Starches (potatoes, bread) and dietary fibre (insoluble; bran, soluble; lentils, beans, oatmeal)

Question 8

Name simple carbohydrates and food sources

Answer 8

Sugars; monosaccharides (glucose, fruit, honey, milk). Disaccharides (table sugar, milk, fermentation and alcohol production)

Question 9

Make up of the three disaccharides

Answer 9

Sucrose: glucose and fructose
Lactose: Glucose and galactose
Maltose: Glucose and glucose

Question 10

Describe Glycogen

Answer 10

Storage form of glucose in the liver.

Only have around 12 hours supply so needs constant replenishment.

Question 11

Steps of digestion of carbohydrates

Answer 11

1) Break down through chewing and cooking
2) Salivary amylase breaking down polysaccharides to smaller subchains
3) In stomach gastric acid deactivates amylase halting digestion process
4) In the Duodenum pancreatic amylase, released after stimulation by CCK, breaks polysaccharides into maltose, maltotriose and alpha limit dextrins
5) Further break down of the above occurs by disaccharidases (maltase, sucrase, lactase) where end product is monosaccharides.
6) Monosaccharides and absorbed by the enterocytes

Question 12

Absorption of monosaccharides

Answer 12

1) Glucose and galactose absorbed via active transport (GLUT transport proteins), fructose via passive diffusion.
2) Travel via portal system to the liver
3) In the liver galactose and fructose are converted to glucose.

Question 13

Lactose malabsorption

Answer 13

When there is a deficiency of lactase resulting in ado symptoms after consuming lactase.
Avoid milk products

Question 14

Benefits of soluble dietary fibre and dietary sources

Answer 14

• Feeds the microbiota in our distal gut (fermented by bacteria to SFA)
• Prolongs stomach emptying time
• Lowers cholesterol and LDL
• Regulates blood sugar
• Pulses and oatmeal

Question 15

Insoluble

Answer 15

• Softens stools

- Increases transit time