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FOOD20003 > 5.2 Carbohydrates (nutrition) > Flashcards

5.2 Carbohydrates (nutrition) Flashcards

1
Q

Why is glucose so important for the brain?

A
  • It is the primary energy substrate in the brain and the body needs to meet the continuous high metabolic demand in a situation of varying plasma glucose level.
  • Blood brain barrier only allows glucose to cross, not other pathogens or solutes in the blood
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2
Q

How might carbohydrates have an impact on decision making?

A
  • Research has linked carbohydrates to mood and decision making
  • People who had a high-carbohydrate meal were more likely to implement social punishment when playing the ‘ultimatum game’ than those who ate high- protein breakfasts.
  • Scientists speculate this may be caused by dopamine levels, which are higher after eating carbohydrates.
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3
Q
A
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4
Q

How does fibre differ from starch?

A

Bonds between glucose molecules in fibre cannot be broken by human enzymes. It passes through the body and therefore contributes little or no energy

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5
Q

What is cellulose?

A
  • Polysaccharide consisting of linear chains of several hundred to many thousand glucose units
  • Important structural component of the cell wall of green plants
  • Straight chain polymer and hydrogen bonds between each of the chains gives it structural rigidity
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6
Q

Who can breakdown cellulose?

A

Ruminant animals can breakdown cellulose with the aid of cellulase producing bacteria

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7
Q
A
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8
Q

Starch breakdown

A
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9
Q

Starch breakdown vs fibre

A
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10
Q

Starch breakdown vs fibre

A
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11
Q

Starch breakdown vs fibre

A
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12
Q

How does the digestion of amylose compare to amylopectin?

A
  • Different rate of digestion for carbohydrates
  • Unbranched amylose chains more slowly digested that branched chains (amylopectin)
  • In branched form, enzymes have more places to attack and can release glucose into the bloodstream more quickly
  • Amylose to amylopectin ratio predict GI of food
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13
Q

What are the two categories of fibre and where are they found?

A
  • All plant foods, vegetables, fruit, legumes and grains, contain a mixture of fibres.
  • Insoluble fibre
  • Soluble fibre.
  • There is usually much more insoluble fibre in plant foods than soluble fibre.
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14
Q

What is resistant starch?

A

Acts in a similar way to fibre. Doesn’t get digested and ends up as food for bacteria in the large intestine

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15
Q

How does soluble vs insolbule fibre affect digestion?

A
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16
Q

How are glucose, galactose and fructose absorbed in digestion?

A
  • Glucose and galactose traverse intestinal cells by active transport which requires energy
  • Fructose absorbed by facilitated diffusion (requires specific carrier) which slows its entry to the blood stream
  • Fructose and galactose are converted to glucose in the liver, extra step delays blood glucose rise
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17
Q

How does lactase activity change in people?

A
  • Only a small percent (~30%) retain enough lactase to digest and absorb lactose in adult life
  • Lactase activity declines with age or damaged intestinal villi
  • Symptoms include bloating, abdominal discomfort and diarrhoea
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18
Q

How can lactose intolerance be managed?

A
  • increasing consumption of milk products gradually
  • mixing dairy with other foods
  • spreading dairy intake throughout the day
  • use of acidophilus milk, yoghurt or lactose-free products
  • use of enzymes.
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19
Q

What are FODMAPs?

A
  • Large group of short chain carbohydrates and sugar alcohols that are found in all sorts of foods and drinks
  • These sugars can be poorly absorbed in the small intestine and fermented by bacteria to produce gas
20
Q

What can a diet high in FODMAPs cause?

A
  • For some people, a diet high in FODMAPs can cause a range of abdominal symptoms such as bloating, excess wind, distension, abdominal pain, constipation or diarrhoea.
  • Following a low FODMAP diet can help manage these abdominal symptoms - 75% of people with IBS experience relief from their symptoms with a low FODMAP diet
21
Q
A
22
Q

What is protein sparing action?

A

Having adequate carbohydrate in the diet to prevent the breakdown of protein for energy

23
Q

What are these known as?

A

Ketone bodies

24
Q

What are ketone bodies?

A

Metabolic products that are produced during excessive breakdown of fatty acids

25
Q

What causes ketosis?

A

During prolonged starvation, very low carb diets and uncontrolled diabetes, ketones accumulate in the blood causing ketosis

26
Q

How does ketoacidosis come about?

A

Very high levels of blood ketones can disturb the body’s normal acid base balance leading to ketoacidosis, a life threatening condition

27
Q

What is the pathway for maintaining blood glucose homeostasis?

A
28
Q

What happens in type 1 diabetes?

A
  • The pancreas is faulty and insulin is not produced, usually childhood onset.
  • It was fatal in the past now controlled with insulin injections.
  • The cause is unknown.
29
Q

What is type 2 diabetes?

A
  • Large amounts of insulin secreted but the insulin receptor on the body’s cells are faulty and cells fail to respond to take up glucose as they should
  • Generally adult onset with fat gain, also some genetic component (insulin resistance)
30
Q

How is this curve interpreted?

A
31
Q

What factors affect the glycaemic response?

A
32
Q

Which sugars and starch have higher GI?

A
33
Q

What might be the health effects of eating a low GI diet?

A

Improvements in

  • BOdy weight
  • Blood lipids
  • Blood glucose control for type 2 diabetes
34
Q

Why is the usefulness of GI being debated?

A
  • Relatively few foods have been tested
  • Responses to food vary widely between individuals
  • Not always indicated on nutritional labels and is not intuitively apparent.
  • Cooking method and how it’s eaten (ie. mixed meal, standard serve vs 50g CHO portion) can effect the glycaemic response
35
Q

What is the range of values for classifying food as high low or medium GI?

A
36
Q

What are the health effects of added sugars?

A
  • Excessive sugar intake can contribute to the development of nutrient deficiencies and dental caries.
  • Sugars ferment in the mouth, and can produce an acid that erodes tooth enamel causing tooth decay.
  • Not all sugars need to be avoided; only concentrated sources (e.g. soft drink, lollies, etc.)
37
Q

What are the three groups of alternative sweeteners?

A
  1. Artificial sweeteners. Also known as ‘non nutritive sweeteners’ because they provide no energy and no carbohydrate such as aspartame, sucralose
  2. Herbal products - Stevia. A herbal product that provides no energy or carbohydrates
  3. Sugar alcohols. ‘Nutritive sweeteners’ because they still provide kilojoules. They will evoke a blood sugar response. Eg isomalt, mannitol, sorbitol
38
Q

How does a high fibre diet benefit heart disease?

A
39
Q

How does high fibre diet benefit gastrointestinal health?

A
40
Q

How does a high fibre diet lower risk of cancer?

A
41
Q

How does a high fibre diet lower risk of diabetes?

A
42
Q

How does high fibre diet improve weight management?

A
43
Q

What are the drawbacks of a high fibre diet?

A
44
Q

What is the reccomended dietary intake of carbohydrate?

A
45
Q

What is the reccomended dietary intake of fibre?

A

FOOD20003 (14 decks)

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