Carbohydrates And Sugars Flashcards
What are the functions of carbohydrates
- energy, physical and mental
- stimulate insulin production and satiety
- promote digestive health
How much energy does 1g carb contain
4kal
How does carbohydrates effect insulin
Absorbed
Blood sugar rises
Insulin released
Insulin allows muscle, liver and fat cells to absorb carbohydrates for energy
What is the chemical composition of carbohydrate
Carbon, hydrogen, oxygen
1:2:1
What are the two types of carbohydrates
Simple
- monosaccharides
-disaccharide
Complex
- polysaccharide
What are the three types of monosaccharides
Glucose
Fructose
Galactose
What are the three types of disaccharides
Maltose
Sucrose
Galactose
What are the two types of polysaccharides
Starches
Fibres
Explain monosaccharides
Glucose = main = sweets, honey, sugar, fruit and juice
Fructose = transported to liver and metabolised = honey, fruit, veg
Galactose = milk sugar
Explain disaccharide
Maltose
- 2x glucose
- plants and cereal grains, certain veg
Sucrose
- glucose + fructose
- refined table sugar, honey, maple syrup
Lactose
- glucose + galactose
- milk and products
Explain polysaccharides
Main types in diet are long chains of glucose
Also long chains of indigestible e.g cellulose and gums
Starches
- potatoes, bread ect
Fibres
- whole grains, beans, nuts
What parts of the body are involved in carbohydrate digestion
Mouth
Small intestines
Small intestine brush border
Liver
Large intestine
Explain carbohydrate digestion in the mouth
Mechanical digestion
Enzymatic digestion
- break down larger carbon such as starch
Salivary amylase
- break into shorter polysaccharides and maltose
- large molecules can’t be absorbed directly so need this breakdown
- smaller ones don’t go through this
Explain enzymatic digestion in the small intestine
Uses pancreatic amylase, secreted by pancreas
- into shorter polysaccharides and maltose
Explain digestion of carbohydrates in small intestinal brush border
Disaccaridases
Break di into mono
Mono the absorbed into the bloodstream for transport into the liver
Explain monosaccharide metabolism in the liver
Glycogenesis
- stored as liver glycogen
- stored as muscle glycogen
Blood glucose regulation
- glucose enters the bloodstream to maintain blood glucose levels
Energy production
- seed in glycolysis to produce ATP
Conversion into fat
- lipogenesis
- stored in body as fat cells o
Explain the role of the large intestine in carbohydrate metabolism
Gut micro biota, colonic bacteria = fermentation of dietary fibre to feed gut microbes
Fermentation releases energy
Short chain fatty acids released during fermentation, support gut health and other bodily functions
Gas production is a natural biproduct of fermentation
What is the role of dietary fibre
- reduce constipation
- reduce cv disease and cancer
- reduce type 2 diabetes and obesity
- increase gut health
- increase mental health
What is lactose intolerance
In normal people, lactose is digested at intestinal brush border inti glucose and galactose via lactase
Intolerance = body dosent produce enough lactase to break down lactose, meaning it passes into large intestine
= gastrointestinal symptoms
What does eat lancet say about carbohydrates
Minimise added sugar
Explain current intakes vs planetary health
No groups meet recommended targets, especially of whole grains + nuts
What are the environmental effect of carbohydrates
Sustainable
What is glycemic index
Rank based on speed of digestion/ how quickly raised blood sugar
Used to just look at fibre content
Methods are reductionist and simplistic, ignore complexity of carbohydrates quality
Explain the holistic model of carbohydrate quality
Combines traditional indices e.g protein quality and environmental stability, degree of processing
Method still needs more work
What is DALY
Disability affected life years
YLD - years lived with disability
YLL - years of life lost
Explain inequalities in health
Most deprived areas in uk = 60 healthy years and 12 unhealthy vs 72 and 12
What are uk dietary guidelines based on
Evidence from independent expert committees e,g
Scientific advisory committee on nutrition
How are dietary guidelines formed
Hierarchy of research evidence
Study design effects how results interpreted and their strength
Non human
Observation
Intervention
Meta analysis and systematic reviews
What are the broad classifications of non human studies
In vitro studies - performed on isolated cells or tissue - less expensive and time consuming but can’t apply to whole living organisms
Animal studies - in vivo
Time and cost good
Easy to control
Applicability bad
Explain broad classifications of human studies
Observational - without intervention
Intervention - gold standard
What are the issues with observation
Association does not mean causation
Explain RCTs, intervention studies
Randomised control trials
- can provide evidence of cause and effect
- higher quality evidence
- manipulation IV
Expensive, ethics, compliance and samp size
What are SACNs carbohydrate recommendations
Should be 50%
Sources more important than quantity
Evidence from both prospective cohort studies and RCTs indicated total carbohydrate intake appears neither detrimental nor beneficial to heath
What are SACNs fibre recommendations
Increase to 30g
15g a day under 5
20 for u 11
25 u 16
All age groups fail to meet recommendations
What are free sugars
All sugars, mono and di which are added by manufacturers and sugars naturally present in honey, sugar, fruit juice
Can be consumed more quickly and are detrimental to health
Which sugars do not count as free sugars
Lactose - when naturally present in milk and milk products
Sugars contained within the cellular structure of foods
What happens when blend fruit
No longer in cellular structure = free sugars
What were the findings on SSBs
Greater weight gain vs non caroucallly sweetened beverages
What are the SACN recommendations for free sugars
I rage should not exceed 5% total dietary intake from 2+ years
Minimise SSBs
Male = 30g
Female = 24g
Child = 19
Can of coke = 35
All a be groups exceed recommended
Explain policy actions to reduce free sugar intake
Soft drinks industry levy
- more than 5g/100 =0.05 g tax
- even more if more than 8
Has encouraged reformulation
- 2015-19 -47000 tons of sugar in uk drink per year
Raise money for public health
Public heath voluntary sugar reduction programme
- aim to reduce sugar in 10 categories by 20% by 2020, only did 3.5%
= must be mandatory
- child friendly characters
- stricter advertising
