Human Nutrition (T2) Flashcards
What are carbohydrates made of and what % of the human body mass do they make up?
Carbon, hydrogen and oxygen. They form 5% of the human body mass.
What are the five main groups of food substances?
- carbohydrates
- lipids
- proteins
- minerals
- vitamins
Carbohydrates are the body’s main supply of energy. How is this energy produced?
Cells produce this energy by oxidising glucose via a process called respiration which takes place in the mitochondria of the cells.
Give some examples of carbohydrates as sugars…
- glucose, found naturally in many sweet tasting foods including fruit and vegetables
- fructose, found in fruit
- lactose, found in milk
- sucrose, ordinary table sugar
What two properties do sugars have?
- they all taste sweet
- they are all soluble in water
What is the main sugar transported through plant stems?
Sucrose
Most of the carbohydrates in our diet come from …… ?
Starch
Describe starch..
- starch is a large insoluble molecule and is found as a storage carbohydrate in many plants, eg: potato, rice, wheat and millet
- starch is made up of long chains of hundreds of glucose molecules joined together and is therefore called a polymer of glucose
- starch is only found in plant cells but animal cells contains a similar carbohydrate called glycogen
Describe glycogen..
- found in animal cells
- made from many glucose units
- found in tissues within the liver and muscles where it’s role is to act as an energy store
Along with starch and glycogen, what other carbohydrate is a polymer of glucose?
Cellulose, which forms plant cell walls
How does the body absorb large carbohydrates like starch and glycogen?
Large carbohydrates such as starch and glycogen must be broken down into smaller, simple sugars during digestion so they can be absorbed into the blood.
Describe cellulose and how it can interact with the human body..
- human guts do not produce the enzyme required to break down the cellulose molecule
- however cellulose forms the dietary fibre (roughage) which provides the muscles of the gut with something to push against as food is moved through the intestines
- this helps to keep the gut moving and helps prevent serious diseases of the intestine like colitis or bowel cancer
Describe how you can test for starch…
- glucose is sweet and dissolves in water while starch is not sweet and does not dissolve
- a further test is to shine a beam of light through solutions of each
- this is the “Tyndall beam effect” and dispersal only happens in starch as the large starch molecules are big enough to affect the light
- you can also add iodine solution (red) and see if it turns black, eg: if you add iodine to a peeled potato it will turn black
Describe testing for glucose…
- Benedict’s or Fehling’s reagent is used to test for glucose but not sucrose
- you heat sugar with either of these chemicals and observe the colour change from blue to orange
- this reaction occurs because glucose is a reducing sugar, ie: it can help another chemical to be reduced
Benedict’s or Fehling’s reagent is used to test for glucose, fructose, maltose and other sugars but not..
Sucrose
What are lipids?
- can be fats or oils
- also contain the same three elements as carbohydrates; carbon, hydrogen and oxygen
- however the proportion of oxygen in a lipid is much lower than in carbohydrates
List seven sources of fats from animals…
- meat
- butter
- cheese
- milk
- eggs
- oily fish
- foods fried in fat or oil
List four examples of plant oils…
- olive oil
- corn oil
- rapeseed oil
- products made from oils like margarine
What % of our body’s fats are lipids?
Around 10%
Lipids are made of two types of molecules / units called…
Glycerol and fatty acids
How is fat used by the body to its advantage?
- fat is deposited around the body as a long-term store of energy, eg: under the skin and around the heart and kidneys
- under the skin, fat acts as an insulation layer, reducing heat loss at the surface of the body
- fat around organs can provide protection from damage
What is glycerol?
An oily liquid also knows as ‘glycerine’ and used in many types of cosmetics
To form a lipid, what needs to join with what?
A single molecule or glycerol is joined to three fatty acid molecules
What are proteins made up of?
Carbon, hydrogen, oxygen, nitrogen and sometimes sulphur
Proteins are polymers made from…
20 different sub units called amino acids
What % of our body mass is made up of proteins?
Around 18%
List three compounds in the body which are proteins..
- enzymes
- hormones
- anti-bodies
What is protein needed for in the body?
The growth and repair of body cells and tissues
List four sources of proteins from animal products..
- meat
- fish
- cheese
- eggs
List three sources of proteins from plant material…
- beans
- peas
- nuts
What is the RDA for protein?
70g
In poorer countries what disease can a lack of protein lead to?
A protein deficiency disease called ‘kwashiorkor’
What are the two types of vitamin?
- fat soluble
- water soluble
Describe fat soluble vitamins..
- found mainly in fatty foods like butter, lard, vegetable oils, dairy, liver and oily fish
- the body stores these in the liver and fatty tissues for future use
- these stores can build up but too many can be harmful
- eg: A, D, E, K
Describe water soluble vitamins..
- these are not stored in your body so you need them more frequently than fat soluble vitamins
- if you take in more than you need your body gets rid of the excess when it urinates
- found in fruit, vegetables and grains
- can be destroyed by heat or by being exposed to the air
- can also be lost in water used for cooking
- eg: C, B, folic acid
Minerals are necessary to..
- build strong bones and teeth
- control body fluids inside and outside cells
- turning the food you eat into energy
Minerals are found in..
- meat
- cereals
- fish
- milk and dairy
- vegetables
- fruit and nuts
Name two essential minerals..
- calcium
- iron
Trace elements are needed, but in much smaller amounts than vitamins and minerals. Give two examples or trace elements and if what kind of food are they found?
- iodine and fluoride
- found in small amounts in food like meat, fish, cereals, milk, dairy, nuts
List some advantages of fibre..
Can help prevent heart disease, diabetes, weight gain and some cancers. Can also help improve digestive health.
What is the RDA for fibre?
18g (but the average person in the UK manages 14g)
What are the two types of fibre?
- soluble
- insoluble
Describe soluble fibre and give some examples…
- can be digested by the body
- may help remove the amount of cholesterol in your blood
- if constipated, gradually increasing sources of soluble fibre can help soften stools
Eg: oats, barley, rye, bananas, apples, carrots, potatoes, golden linseed
Describe insoluble fibre and give some examples…
- can’t be digested
- passes through gut without being broken down and helps other food move through the digestive system
- keeps bowels healthy and prevents digestive problems
- if you have diarrhoea you should limit the amount in your diet
Eg: wholemeal bread, bran, cereals, nuts and seeds (EXCEPT golden linseed!)
Around how much energy does a new born baby need a day?
2000kJ
Around how much energy does a child, 2, need a day?
5000kJ
Around how much energy does a child, 6, need a day?
7500kJ
Around how much energy does a girl, 12-14, need a day?
9000kJ
Around how much energy does a boy, 12-14, need a day?
11,000kJ
Around how much energy does a girl, 15-17, need a day?
9000kJ
Around how much energy does a boy, 15-17, need a day?
12000kJ
Around how much energy does a female office worker need a day?
9500kJ
Around how much energy does a male office worker need a day?
10500kJ
Around how much energy does a heavy manual worker need a day?
15000kJ
Around how much energy does a pregnant woman need a day?
10000kJ
Around how much energy does a breast feeding mum need a day?
11300kJ
Recommended energy requirements vary with age, sex and pregnancy and are affected by diet. Give a couple of examples…
- in pregnancy a woman may need extra iron or calcium to ensure the correct growth of the foetus.
- in younger women, the blood loss that occurs during menstruation can result in conditions like anaemia, so extra iron can be required.
What are the 7 building blocks for a healthy diet…
- carbohydrates
- fats
- protein
- vitamins
- minerals
- fibre
- water
Describe carbohydrates as part of the 7 building blocks of a healthy diet…
- provide quick energy
- 60% of our diet should comprise carbs
- in sport, marathon runners will ‘load’ before an event
Eg: pastas, cereals, potatoes
Describe fats as part of the 7 building blocks of a healthy diet..
- provide slow energy
- 25% of our diet should be fat
- used when walking and taking part in low impact excersise
Eg: oils, dairy, fish, nuts
Describe protein as part of the 7 building blocks of a healthy diet…
- builds and repairs muscle
- only need 15% of our diet to be protein
- in sport, used when training hard and in recovery
Eg: meat, pulses, fish
Describe vitamins as part of the 7 building blocks of a balanced diet..
- help the body work
- help concentration
- in sport they can help you stay calm and make quick decisions
Eg: fresh fruit and vegetables
What does vitamin A help with?
Vision
What does vitamin B help with?
Energy production
What does vitamin C help with?
Healthy skin and immune system
What does vitamin D help with?
Bones and teeth
Describe minerals as part of the 7 building blocks of a balanced diet..
- help release energy from food
- help with decision making
- in sport, essential when training hard and competing
Eg: fruit, vegetables and fish
What does calcium help with?
Strengthening bones
What does the mineral iodine help with?
Energy production
What does the mineral iron help with?
Preventing fatigue
Describe fibre as part of the 7 building blocks of a balanced diet..
- fills you up and keeps you regular
- helps with weight control
- in sport, healthy digestion increases performance
Eg: fresh fruit and vegetables, whole grain cereals
Describe water as part of the 7 building blocks of a balanced diet..
- maintains fluid levels
- used in sport to replenish fluid when you sweat, preventing dehydration
Eg: the tap!
What is the energy that the body takes in from food measured in?
Kilojoules or kilocalories
What is your BMR?
- Basic Metabolic Rate
- the number of kilojoules you use to stay alive each day
What is your PAL?
- Physical Activity Level
- the number of kJ you use to fuel your physical activity
What does the sum of your BMR and PAL equal?
Your daily requirement
What kind of people would need more energy for their BMR?
Large people
What kind of people would need ore energy for their PAL?
Athletes
Describe a simple experiment to see how much energy there is in food..
- take samples of food and set them alight in turn
- burn food samples under a boiling tube containing a measured amount of water
- measure the temperature increase in water
- calculate the amount of energy needed to cause the temperature increase
- this gives an estimate of the amount of energy stored in the food
