energy and macronutrients Flashcards
name 3 macronutrients?
carbs
proteins
fats and oils (lipids)
name 2 micronutrients?
minerals
vitamin
name 4 classes of vitamins?
macronutrients
micronutrients
water
alcohol
what is the chemical energy from nutrients used for?
protein synthesis
what is the electrical energy from nutrients used for?
maintain ionic gradients
what is the mechanical energy from nutrients used for?
muscle contraction
what is heat energy from nutrients used for?
maintain body temperature
ow is energy measured?
units of kilocalories (kcal) or kilojoules (kJ)
how many kilojoules are in 1 calorie?
4.18
what does calorie mean?
the energy needed to raise the temperature of 1 gram of water from 14.5 to 15.5oc
what does joule mean?
the energy used when 1 gram is moved 1 metre by the force of 1 newton
what is more energy dense: fat, carbs or protein?
fat
what makes a food more energy dense?
high fat or low water
what makes up the total energy expenditure (TEE)?
Basal metabolic rate 60-75%
physical activity 10-40% (can be up to 70)
thermogenesis 10-20%
what is basal metabolic rate? (BMR)
vital body functions eg maintaining electrochemical gradient, cell and protein turnover, lung and heart function etc.
what is thermogenesis?
including that through metabolising food (diet included), through muscle action (dynamic and isometric) and through climate (cold induced)
how do you achieve energy balance?
energy intake = energy output
what is positive energy balance?
energy intake > energy output
when would you like to have a positive energy balance?
growth, pregnancy, lactation
when is a positive energy balance not desirable?
over a long period of time as excess energy is stored as fat which leads to health problems
what is negative energy balance?
energy intake< energy output
what happens with a negative energy balance over medium and long term?
medium - fat stores used for energy
long - protein used for energy so health problems
what effects energy requirements?
body size
age
activity
pregnancy/ lactation
disease, trauma and treatments
what is calorimetry?
metabolic chamber: expensive and artificial
what is indirect calorimetry?
o2 and co2 measurements: methodological limitations
how were energy dietary reference values set?
energy expenditure measurements
why use estimated average requirement rather than reference nutrient intake for energy?
due to the health consequences for overconsumption
what is the most important energy food source and how much of the total intake does it take up?
carbohydrates
40-80%
how are carbohydrates made?
synthesised by plants from carbon dioxide and water through photosynthesis
name the 2 types of carbohydrates?
sugars
polysaccharides
name the 2 sub groups of polysaccharides?
NSP - nonstarch polysaccharide
starch
what are the 2 types of NSP’s?
celluloses
hemicelluloses
what are the 2 types of sugars?
monosaccharides and disaccharides
what are polyols?
sugar alcohols
how many monosaccharides are in oligosaccharides?
between 3 and 9
how is malto-oligosaccharides made?
from hydrolysis of starch
how many monosaccharides are in a polysaccharide?
over 9
name 3 types of polysaccharides?
starch
glycogen
non-starch polysaccharides
name 3 types of monosaccharides?
glucose, galactose, fructose
name 3 types of disaccharides?
sucrose, lactose, maltose
what are sugar alcohols?
- found naturally eg. cherries
- commercially from glucose
- used in diabetic products
- absorbed in gut slowly
where can oligosaccharides be found?
plant seeds, many legumes such as peas and beans
how are oligosaccharides digested?
can’t be broken down by digestive enzymes
- fermented in large intestine
what are dextrins?
short chains of glucose, formed by deflation of starch by partial hydrolysis, used in oral tube feeding preparations
what is glycogen?
storage carbohydrate in humans and animals
what is the 2 types of sugars?
intrinsic and extrinsic
what are non-milk extrinsic sugars?
mostly sucrose used as table sugar and baked goods also honey and fruit juices
what is extrinsic milk sugars?
lactose
what is intrinsic sugars?
fructose, glucose in fruit and veg etc
wha are free sugars?
Monosaccharides and disaccharides added to foods by manufacturer, cook or consumer plus naturally present in honey, syrups and unsweetened fruit juices.
what are added sugars?
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 total sugars?
describes total amount of sugars from all sources
what are the 2 main types of starch?
Amylose and amylopectin
what is starch?
storage carbohydrate in cereal grains and potatoes
exists in granules
what is amylose?
unbranched chain of glucose with alpha (1-4) linkages
what is amylopectin?
long highly branched polymer
15-30 glucose units
alpha(1-4) linkages in each branch
branches linked by alpha(1-6) linkages
describe the solubility and ingestibility of starch?
insoluble in water
indigestible when raw
- process of cooking makes starch digestible
give examples of available and non-available carbohydrates?
available - starch and sugars
non-available - cellulose and hemicellulose
what happens to food not ingested in the small intestine?
- 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 2 categories can dietary fibres be divided into?
- non starch polysaccharides
- resistant oligosaccharides
- resistant starch
what are soluble NSP?
- found in oats, beans, pulses, fruits and veg
- ‘cholesterol - lowering effect’
what are insoluble NSPs?
- found mainly in wheat bran
- ‘faecal bulking’ effect - absorbs water, adds bulk and decreases/speeds up transit time
where are NSPs fermented?
in large intestine by bacteria
what carbohydrate bonds can we digest?
alpha 1-4 glucose by amylase eg starch
alpha 1-6 glucose by glucoamylase-alphadectrinase
glucose fructose - sucrase
glucose galactose - lactase
what is the current recommendation for starchy carbohydrates in the diet?
50%
what is the role of dietary fats?
- energy
- essential fatty acids
- fat soluble vitamins
what is the role of lipids in the body?
- store of energy
- structural role in cell membranes
- metabolic functions
where are fats in foods mainly found?
mainly in triacylglycerols
also cholesterol, plant sterols, phospholipids and fat soluble vitamins
what is the role of essential fatty acids?
- cell membranes
- biologically active compounds eg. eicosanoids
- growth and development
what is the function of proteins?
- major structural and functional components of all cells
- have structural and function roles needed during growth and maintenance
- provide about 10-15% to the dietary energy suply
how many amino acids are there that make up proteins?
20
what does the r group give to a protein?
size
shape
charge
‘basic characteristics’
what are peptide linkages?
amino group of 1 amino acid joins with carboxyl group on another
what is a dipeptide?
2 amino acids joined together by peptide linkages
what is a polypeptide?
more than 2 amino acids joined by peptide linkages
what do proteins consist of?
one or more polypeptides
what do polypeptides consist of?
10 to 1000 amino acids joined by peptide bonds
what gives proteins their structural and functional characteristics?
polypeptides coiling and folding
are amino acids essential?
metabolically essential to the body
however
either essential or non-essential in the body
what are features of essential amino acids?
indispensable
can’t be synthesised in body and can’t be synthesised in sufficient amounts to meet demand
what are features of non essential amino acids?
dispensable
can usually be synthesised from precursors in insufficient amounts to meet demand
give features of conditionally essential amino acids?
in certain situations ie during growth/ childhood or when precursors are insufficient
