carbohydrates and sugars

Question 1

carbohydrates

Answer 1

1g carbs provides 4kcal
provide energy for physical and mental activities
stimulate insulin production and satiety
promote digestive health

Question 2

dietary carbs

Answer 2

simple- monosacharides and disaccharides
complex- polysaccharides
naturally occuring carbs- rice, pasta, legumes + nits
added sugars- desserts etc

Question 3

monosachharides

Answer 3

no more than 6 carbon atoms in structure
glucose- used for energy by body- sources include sweet confectionary, honey, sugar, fruit, fruit juices
fructose- honey, fruit, veg, high fructose corn syrup
galactose- dairy products

Question 4

disaccharides

Answer 4

maltose- glucose + glucose- plants + cereal grains,certain veg
sucrose- glucose + fructose- refined table sugar, honey, maple syrup, F+V
lactorse- glucose + galactose- cows milk and milk products

Question 5

polysaccharised

Answer 5

long chains of glucose molecules bonded together
starches- potatoes, bread, pasta, rice
fibres- non starch polysaccharides- wholgrain, beans, nuts, F+v

Question 6

digestion and aborption

Answer 6

enzymatic digestion occurs in mouth and small intestine (mostly SI)
begins in mouth with mechanical digestion- chewing food, mixing food with saliva
starch (amylose) is broken down by salivary amylase into shorter polysaccharides and maltose lower pH inhibits salivary amylase
bolus will move into SI where pancreatic amylase will continuye the same breakdwon, occurs on large scale in SI

Question 7

SI brush border

Answer 7

disaccharidases break down disaccharides
lactase, maltase and sucrase break down disaccharides to monosachharides

Question 8

monosaccharide metabolism in liver

Answer 8

glucose- stored as lvier glycogen, become part of blood glucose, used to produce energy (glycolysis), stored as muscle glycogen, excess is converted for storage in body fat cells

Question 9

in large intestine

Answer 9

feeding gut microbes
colonic bacteria, gut microbiota ferment dietary fibre to feed themselves
fermentation- provides energy that bacteria need to survive and thrive, released SCFA have a range of benefits for gut health and health of other systems
causes gas production

Question 10

dietary fibre

Answer 10

needed for gut health and benefits overall health
relieve constipation
improve mental health due to brain gut connection
reduce risk of cancer- effects of SCFA on colon
reduces risk of CVD

Question 11

lactose intolerance

Answer 11

impaired ability to digest lactose adequately
lactose passes into LI causing gastorintestinal symptoms
body doesnt produce enough lactase to break down
more common in asian/african background
symptoms can be controlled by changes to diet

Question 12

environmental sustainability

Answer 12

compared to other food sources, carbs are one of the most sustainable food groups for climate health- use less land and produce less greenhouse gases compared to red meat for example

Question 13

defining carb quality

Answer 13

traditionally based on simplistic and reductionist tools eg GI and fibre content
glycemic index shows how quickly a good raises blood glucose levels
not fully realistic as we dont just eat food by itself, we eat different foods together
low include fruit, veg
medium include- wholegrain bread, sugar
high include white bread, fries

Question 14

uk dietary guidelines

Answer 14

govt ditary recommendations reflect evidence based advice from independent expert committees, including scientific advisory committee on nutrition (SACN)
SACN provides advice on UK health dept on matters relating to food, diet and health with a public health focus

Question 15

formation of dietary guidelines

Answer 15

systematic reviews and meta analyses of observational studies and randomised controlled trials conducted to summarise existing evidence
findings from different levels of research are integrated and translated into guidelines and recommendations
eatwell/lancet guide
hierarachy of research evidence is considered
strength of evidence and relevance to real life nutrition decisions will increase as we move from bottom to top of pyramid

Question 16

non human studies

Answer 16

in vitro- performed on isolated cells or tissue samples- less expensive and time consuming than animal or huma. studies but cannot assume that results will appky to whole living organism
animal studies- (in vivo) - less expensive and time intensive than human studies, can see how much food the animal actually consumes, but are only preliminary models of disease

Question 17

observational studies

Answer 17

correlatioon doesnt prove causation

Question 18

cross sectional

Answer 18

collect info about a population of people at one point in time to create a snapshot

Question 19

longitudinal cohort study

Answer 19

follows a group of people over time- measuring factors such as diet and health outcome
strongest type of observational stidy but still cannot show that exposure to a specific diet prevents CVD- has potential for confounding factors- affect the outcome and factors being studied

Question 20

randomised controlled trials

Answer 20

provide evidence of cause and effect
experimental group is exposed to treatment while control is not
both groups are then followed for a comparison to be made between their respective outcomes
blinding ps and or researchers to decrease potential bias
may be hard to get adequate sample size/ compliance to diet

Question 21

systematic reviews and meta analyses

Answer 21

combine relevant studies that have been conducted on research question and summarise their overall conclusions
meta analysis- used statistical analysis of relevant data to summarise
limitations- relying on quality of individual studies which may not be reliable

Question 22

dietary carb and health

Answer 22

SACN report on carb and health- published in 2015
DRV for carbs- maintained at pop average of ~50% of dietary energy intake
evidence from prospective and cohort studies and RCTs indicated total carb intake is not detrimental or beneficial to cardiometabolic health

Question 23

dietary fibre recommendation

Answer 23

SACN reccomend 30g a day for adults
children: 15g (2-5), 20g (5-11), 25g (11-16)

Question 24

why do we need to increase fibre intake

Answer 24

diets rich in fibre are associated with lower incidence of CVD, type 2 diabetes and colorectal cancer
diets rich in fibre decrease intestinal transit time and increase faecal mass
higher intake of oat bran and isolated b glucans (soluble fibres) leads to lower cholsesterol, LDL and tricacylglycerol concentrations and lower BP

Question 25

sugars and SSB

Answer 25

higher consumptions of sugars and sugar containing foods and beverages are associated with increased risk of dental caries
greater consumptio n of SSBs is associated with increased risk of type 2 diabetes
increased intake of free sugars may also lead to increased energy intake

effect of increased free sugars–> increased weight gain

Question 26

free sugars

Answer 26

all sugars added to food and beverages by the manufacturer, cook or consumer
sugars present in honey, maple syrup, fruit juices also included
DRV across population- intake fo free sugars should not exceed 5% of dietary energy intake

Question 27

non free sugars

Answer 27

lactose (milk sugars) when naturally present in milk and milk products
sugars contained in cellular structure of food
when fruit and veg are juices- fibre content is extemely reduced

Question 28

policy actions

Answer 28

advice to limit food and drinks high in free sugars
SSBs are a key focus + ~ 40 countries worldwide have tax on these products
soft drink industry levy introduced in 2018

Question 29

does sugar levy work?

Answer 29

• has encourages reformulation and reduced the volume of sugar purchased through soft drinks
• more than 47000 tonnes of sugar have been removed from soft drinks every year form 2015-19
• estimated that the levy was associated with preventing over 5000 cases of obesity in girls in y6 in england (rogers et al)

Question 30

pyramid of studies

Answer 30

low to high in strength of evidence/relevance of real life nutrition decisions

1. non human studies- animal studies/ in vitro cell studies (cell culture)
2. observational studies- cohort studies, case control studies, cross sectional studies
3. intervention studies- randomised controll studies and other clinical trials
4. meta analyses and systematic reviews