Sugars + Carbohydrates

Question 1

What’s the energy source from carbs? (kcal)

Answer 1

1g carbs = 4kcal

Question 2

What’s the key roles of carbs in the body?

Answer 2

• energy for physical + mental activities
• stimulate insulin production + satiety
• promote digestive health

Question 3

What are the 2 types of dietary carbs?

Answer 3

Naturally occuring - in fruit etc

Added sugars - in sweet desserts etc

Question 4

What 2 groups are carbs split into?

Answer 4

Simple - monosaccharides (glucose, fructose, galactose) and disaccharides (maltose, sucrose, lactose)

Complex - polysaccharides (starches, fibre)

Question 5

Give examples of where each of monosaccharides are found

Answer 5

• Glucose = sweet confectionary, honey, sugar, fruit (main carb)
• Fructose = honey, fruit, some veg
• Galactose = milk sugar

Question 6

Give examples of where each of disaccharides are found

Answer 6

• Maltose= plants, certain veg, cereal grains
• Sucrose= honey, fruit, some veg
• Lactose = milk sugar / dairy products

Question 7

Give examples of where each of polysaccharides are found

Answer 7

• Starches = potatoes, bread, rice, pasta + cereals
• Fibres (non-starch) = wholegrains, beans, nuts, F+V

Fibres are indigestible chains of glucose molecules (cellulose, inulin)

Question 8

What classifies a monosaccharide?

Answer 8

No more than 6 carbon atoms

Question 9

After absorption, where is fructose transported to?

Answer 9

The liver to be metabolised rapidly into products like glucose or glycogen or fat and that depends on metabolic state of individuals

e.g. if got excess glucose, it will be stored at adipose tissue in fat stores

Question 10

What are the general steps of digestion + absorption of carbs?

Answer 10

1. Mouth - mechanical + enzymatic digestion of starch
2. Small intestine - enzymatic digestion of starch
3. monosaccharide metabolism in liver

Question 11

Digestion + Absorption

Describe what occurs in more detail at the mouth

Answer 11

Salivary amylase breaks down starch into shorter polysaccharides + maltose

• has to be broken down as too large to be absorbed into bloodstream

Question 12

Digestion + Absorption

Describe what occurs in more detail at the small intestine

Answer 12

Pancreatic amylase + disaccharidases from small intestine brush border = disaccharides into monosaccharide constituents

• these pass through enterocytes and absorbed into blood stream to be taken to the liver
• any unabsorbed CHO is transported to the large intestine

Question 13

Digestion + Absorption

Describe what occurs in more detail at the liver

Answer 13

Galactose + fructose are converted to glucose then…

1. Glycogenesis - glucose are stored as liver glycogen + muscle glycogen
2. Blood glucose regulation - if glucose enters blood stream, its used for regulation
3. energy production - used in glycolysis for ATP
4. Conversion to fat - converted + stored as body fat cells (lipogenesis) - only if excess glucose

Question 14

What happens with the undigested carbohydrates?

Answer 14

(Mainly fibre)

In the large intestine, gut (colonic) bacteria ferments fibre for survival + growth

The fermentation process…
- provides an energy source for bacterial survival
- releases short-chain fatty acids to support gut health
- produces gas as a natural by-product

Question 15

Why is dietary fibre important?

Answer 15

• relieve constipation
• reduce risk of CVD + T2D + cancers
• oral health
• mental health
• improve gut microbiome + health
• weight management

Question 16

What is a lactose intolerance?

Answer 16

The body has an impaired ability to digest lactose adequately

Question 17

What occurs to the lactose that different to normal?

Answer 17

Normal digestion - digested by lactase at intestinal brush border = glucose + galactose

Intolerance - lactose passes to large intestine (not enough lactase ) = GI symptoms

• abdominal pain, diarrhoea, nausea
• hereditary

Question 18

How can a lactose intolerance be managed?

Answer 18

Use diary free products (nut-milk)

Lactase enzyme tablet

Question 19

What do Eat-Lancet say is the healthy reference diet of carb sources?

Answer 19

• whole grains
• fruit + veg
• minimising intake of added sugars

Question 20

Why is removing wholegrains (e.g. eating white rice, white bread etc) considered worse?

Answer 20

It leads to a loss of nutrients + fibre = a increased risk of metabolic diseases + cancer

Question 21

Is there differences in intake of carbs in different continents?

Answer 21

Based on research, europe + central Asia are behind greatly on whole-grains

• the Mediterranean diet aligns well with recommendations (rich in whole-grains + fruit and veg)

Question 22

How is carb quality measured?

Answer 22

2 traditional methods…

1. Glycaemic index - rates how quickly carb foods raise blood sugar
   - Low GI (0-55) - break down slowly during digestion, raising blood sugar slowly
   - Medium GI (56-69) - break + raise moderately
   - High GI (70+) - break + raise rapidly
2. Fibre content - amount of fibre as a basic indicator as quality

Question 23

What are the limitations of these traditional methods of carb quality?

Answer 23

X - too simplistic + reductionist

X - don’t fully capture complexity of carb quality

Question 24

Describe a more holistic approach that can be taken to assessing carb quality

Answer 24

It combines traditional indices with other indices (protein quality, environmental sustainability, degree of processing)

• aims to positively impact both health + environmental outcomes but needs further validation before its used more widespread

Question 25

What are the current traditional indices?

Answer 25

1. Glycaemic index 2. Wholegrain content 3. Fibre content 4. % added sugars

Question 26

Why is it a government focus to improve UK pop. dietary intakes?

Answer 26

There is a significant role of diet in the burden of disease - this impacts health services - also contributes to health inequalities (least deprived has better health etc) Unhealthy diet is one of largest contributors to overall disease burden

Question 27

How are guidelines formed?

Answer 27

A hierarchy of evidence is considered (ranging from non-human studies to systematic reviews) Non-human studies -> observational studies -> intervention studies -> meta-analyses + systematic reviews

Question 28

Broad classification of non-human studies What are the 2 types?

Answer 28

1. In-vitro studies - performed on isolated cells or tissue samples - less expensive + time intensive - cannot assume results will apply to whole living organism 2. Animal studies (in-vivo) - can control food intake - less expensive + time intensive than human - only preliminary models of disease (different from human diseases)

Question 29

Broad classification of human studies What are the 2 groups?

Answer 29

1. observational - exposure of participants occurs naturally without any intervention from researchers - correlation does not prove causation however 2. Interventions - experimental group is exposed to treatment while control group is not (exposure is assigned to participants)

Question 30

What are the studies seen in observational research? describe purpose, whether it's strong or not and limitations

Answer 30

Longitudinal cohort studies Purpose - follow a group of people over time + measure factors Design strength - strong as can track changes + associations Limitations: (1) cannot definitively prove that exposure to a specific diet directly prevents CVD and (2) potential for confounding variables to influence results

Question 31

What are the studies seen in intervention research? describe purpose, design + how to reduce bias

Answer 31

Randomised controlled trials Purpose - provide evidence of cause + effect between treatment + outcomes Design - experimental group is exposed to the treatment while control is not Follow-up - both groups then followed for comparison to be made between respective outcomes Minimising bias - 'blinding' participants + researchers to reduce bias

Question 32

Based on the SACN report (2015), what is the dietary reference value for carbs? (as a % of total dietary EI) Are carbs good or bad?

Answer 32

Roughly 50% The evidence indicated that total carb intake appears neither detrimental nor beneficial to cardiometabolic health, colorectal or oral health

Question 33

Based on the SACN report (2015), what is the recommended intake of fibre (2-5, 5-11 and 11-16 yrs + adults) that the pop. need to increase to and why?

Answer 33

2-5yrs = 15g/day 5-11 yrs = 20g/day 11-16 yrs = 25g/day Adults = 30g/day Diets rich in fibre (cereal fibre + wholegrains) are associated with lower incidence of CVD, T2D + colorectal cancer - also decrease intestinal transit times + increase faecal mass

Question 34

What's the benefit of fibres such as oat bran and isolated beta-glucans?

Answer 34

They can lower cholesterol, LDL + triacylglycerol conc + lower BP

Question 35

What are free sugars?

Answer 35

All sugars that are added to food and drinks by manufacturer, cook or consumer as well as sugars naturally present in honey, syrups + fruit juices - these are sugars that are not contained within the cellular structures inside foods

Question 36

Based on the SACN report (2015), what are SSBs and their effect to an individuals health?

Answer 36

SSBs are all 'non-diet' carbonated drinks, coffee/tea with sugar, squash, juice drinks + sports / energy drinks - high consumptions of sugars within foods + drinks = increased risk of dental caries - increased risk of T2D - more free-sugars = more energy intake - weight gain and higher BMI compared to non-calorically sweetened drinks

Question 37

What is the recommendation of free sugars?

Answer 37

Average intake of free sugars should not exceed 5% of total EI from 2yrs+ Consumption of SSBs should be minimised in children + adults - because one can of coke = 35g of free sugars! - more than max daily intake in one go

Question 38

What policy actions have been introduced to reduce free sugars intake?

Answer 38

1. Advice to limit foods + drinks high in free sugars as part of national dietary guidelines 2. SSBs are a key focus - tax 3. Soft drinks industry levy (2018) - tax rate based on sugar content = encouraging reformulation + decreased volume of sugar purchased via drinks

Question 39

How has the sugar tax been beneficial?

Answer 39

2015-19 = reduction of over 47000 tonnes of sugar each year from soft drinks sold £334m in revenue raised in 21-22 alone

Question 40

Describe the Public Health England Voluntary Sugar Reduction Programme... Objective + success

Answer 40

Objective - reduce sugar in 10 food categories by 20% in 2020 Actual reduction was only 3.5%! - were larger reductions for yoghurts, breakfast cereals, ice cream + lollies - smallest reduction for chocolate + puddings

Question 41

As a result, additional strategies are required to lower free sugars in food + drinks List 3 of these

Answer 41

1. A widespread mandatory food industry reformulation approach to get consistent reductions in sugar content 2. Stricter advertising restrictions - especially among young children 3. Criteria for marketing claims needs to have more rigorous standards + eliminate use of child-friendly characters on packaging

Question 42

If the SACN recommendations to reduce sugar intake to 5% of energy intake is achieved in next 10 years, this could....

Answer 42

Reduce the cost on the NHS by $500m per annum by year 10