Dental energy Macro Flashcards
How is energy measured
Calories and Joules
One calorie is equivalent to 4.184 joules
What is a calorie
The energy needed to raise the temperature of 1 gram (g) of water from 14.5 to 15.5ºC
1 kilocalorie (kcal) = 1,000 calories or 1 Calorie (Cal)
What is a Joule
The energy used when 1 gram (g) is moved 1 metre (m) by the force of 1 Newton (N).
1 kilojoule (kJ) = 1,000 joules
1 megajoule (MJ) = 1,000,000 joules
How do you convert from Kcal to Joules
1 kcal = 4.184 kJ
1 MJ = 239 kcal
What is energy density
Energy a food contains per gram
Which is most energy dense
Fat
CHO
Protein
Fat
How can we calculate the total energy content of a food
Burn the food and measure the heat released
What are foods with low energy density
Foods with fewer calories per gram
What is TEE
Total Energy Expenditure
What are the 3 components of TEE
Basal metabolic rate 60 - 75%
Physical activity 10 - 40%
Thermogenesis 10 - 20%
What macronutrients act as an energy store
Fat
Glycogen
Protein
When is energy balance achieved
Energy intake = Energy output
What factors affect energy requirements
Body size
Age
Activity
Pregnancy
Disease/trauma
What are ways to measure energy expenditure
Direct calorimetry (expensive)
Indirect calorimetry
(methodological limitations)
Doubly labelled water (allows measurements without constraint)
How can energy intake be measured
Data from surveys NDNS
Assumes population is in energy balance
Assumes intake data is accurate
What does EAR stand for
Estimated Average Requirement
What is DRV
Dietary reference values
What does RNI stand for
Reference nutrient intake
What does SACN stand for
Scientific advisory committee on Nutrition
Why did SACN review the 1991 energy requirements
Evidence base had moved
Overweight and obesity in the UK increased
How many calories should a grown man and woman consume on average per day
Woman - 2000 kcal
Man - 2500 kcal
What is the chemical structure/classification of CHOs
Monosaccharides
Dissaccharides
Polysaccharides
What is the nutritional classification of CHOs
Sugars
Starches
Non-starch Polysaccharide - dietary fibre
What are the available CHOs
Starch and sugars
Which CHOs are unavailable
Cellulose and hemicellulose
What are some hemicellulose carbohydrates
Xylans
Gum
Pectins
Beta Glucans
What are glucose galactose and fructose
Monosaccharides
What are some disaccharides
Sucrose
Lactose
Maltose
What produces Malto-oligosaccharides
Hydrolysis of starch
What are oligosaccharides
3-9 monosaccharides
What are polyols
sugar alcohols
What are the types of sugar
Intrinsic
Extrinsic
What are intrinsic sugars
Fructose
Glucose
(in fruit and veg)
Where can extrinsic sugars be found
Milk and non milk products
Lactose + sucrose
What are ‘added sugars’
Refers to sugars and syrups that are added during manufacture and preparation but does not capture the sugars present in unsweetened fruit juice or honey.
What are ‘free sugars’
All monosaccharides and disaccharides added to foods by the manufacturer, cook or consumer, plus sugars naturally present in honey, syrups and unsweetened fruit juices.
Under this definition lactose when naturally present in milk and milk products and the sugars contained within the cellular structure of foods (particularly fruits and vegetables) are excluded.
What are ‘total sugars’
Describes the total amount of sugars from all sources (free sugars plus those from milk and those present in the structure of foods such as fruit and vegetables).
What are sugar alcohols
Found naturally e.g.sorbitol in cherries
Commercially - from glucose: CHO group converted to CH2OH
Used in diabetic products – soft drinks, jams, chocolate
Absorbed from gut more slowly – less effect on blood glucose
What are examples Oligosaccharides
Raffinose, Stachyose & Verbascose
Short chain carbohydrates: 3-6 monosaccharides
Found in plant seeds, mainly legumes such as peas & beans
Cannot be broken down by digestive enzymes - fermented in large intestine
What are Dextrins
Short chains of glucose, formed by degradation of starch by partial hydrolysis, used in oral tube feeding preparations
What is Glycogen
Storage carbohydrate in humans and animals
What are the two main types of starch
Amylose (1-4)
Amylopectin (1-4),(1-6)
Why must starch be cooked before ingestion
indigestible when raw
How is starch broken down
Pancreatic amylase
What is dietary fibre
“that portion of food which is derived from cellular walls of plants which is digested very poorly by human beings” Trowell (1972)
What are the three categories of dietary fibre
Non-starch Polysaccharides
-Cellulose and non-cellulose polysaccharides (pectins, glucans, gums, arabinogalactans, mucilages, etc).
Resistant Oligosaccharides
-FOS and GOS
Resistant Starch
Where can soluble NSP be found and what do they do
found in oats, beans & pulses, fruits & vegetables
‘cholesterol-lowering’ effect
Where would insoluble NSP be present and what are their
purpose
found mainly in wheat bran
‘faecal bulking’ effect – absorbs water, adds bulk & decreases/’speeds up’ transit time
What is the best index of dietary fibre
Non Starch Polysaccharides
What are some starch and starch degradation products not (fully) digested in the small intestine of humans
RS1 - enclosed within cell walls structures
E.g. wheat or oats flakes
RS2 - presence of raw starch granules
E.g. green banana, uncooked potato
RS3 - retrograded starch (cooked-cooled)
E.g. potato salad
RS4 - Chemically modified starch
E.g. ‘modified starch’, added to processed foods
What is a prebiotic
A selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora that confers benefits upon host well-bring and health
Which carbohydrate bonds can we digest
Alpha 1-4 glucose by amylase eg starch
Alpha 1-6 glucose by glucoamylase- alphahdextrinase
Glucose fructose – sucrase
Glucose galactose – lactase
What happens to food not digested in the small intestine?
It is fermented by the colonic microflora to short chain fatty acids and gases
Acetic, propionic and butyric acid
All have some health benefits and act as an energy source.
What are the SCFA and their properties
Acetic acid
Main SCFA 60% of total, acts as energy source. Is only SCFA to reach peripheral blood, increases lipid production.
Propionic acid
Removed by liver, may reduce cholesterol synthesis, can be used to make glucose. Stimulates gut cell proliferation
Butyric acid
Main fuel of colonocytes, removed by mucosa, stimulates apoptosis, differentiation of cancer cells in vitro, several stages of cancer in vitro, gut cell proliferation.
What percentage of daily energy intake should free sugars account for according to SACN
No more than 5%
19g or 5 sugar cubes for children aged 4 to 6
24g or 6 sugar cubes for children aged 7 to 10
30g or 7 sugar cubes for 11 years and over, based on average population diets
What are the fibre intake recommendations
16 and over increase intake of fibre to 30g a day,
25g for 11- to 15- year-olds
20g for 5- to 11-year-olds
15g for 2- to 5-year olds
What constitutes as a fat
Compounds made up of carbon, hydrogen and oxygen
What is the role of dietary fats
energy
essential fatty acids
fat-soluble vitamins
Role of lipids in the body
store of energy
structural role in cell membranes
metabolic functions
What structural factors affect the properties of fatty acids
Number of C atoms (chain length)
Presence of “double bonds”
- saturated and unsaturated fatty acids
- cis and trans isomers
- position of double bond, essential fatty acids
