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3.1 Nutrients –
Functions and sources
Nutrition for youth health
• One of the key behavioural determinants that
affects the health and development of
Australia’s youth is food intake
• Nutrition is the process of eating to nourish
our bodies. It is also the scientific study of why
we eat
Nutrients
• To understand how food affects health and
development of youth, it is important to look
at nutrients, how they work (function) and the
foods they are found in (sources)
• Nutrients are the chemical components of
food; they are required by living thing to
maintain life
• There are many different types of nutrients
Types of nutrients
• The many different types of nutrients can be
classified into two main forms:
• Macronutrients: Needed by the body in large
quantities – proteins, carbohydrates, fats and
water
• Micronutrients: Needed by the body in
relatively small amounts – vitamins and
minerals
Protein
• Main function: build, grow and repair cells
• Made up of smaller units called amino acids
• Classified as either complete or incomplete
depending on composition of amino acids
• Food sources include:
– Complete: meat, chicken, cheese, eggs, milk
– Incomplete: rice, legumes, nuts, vegetables
Carbohydrate
• Main function: provide energy or fuel
• Classified as monosaccharides, disaccharides or
polysaccharides
• Food sources include:
– Monosaccharides: glucose and fructose found in
honey and nuts
– Disaccharides: sucrose and lactose found in sugar and
milk
– Polysaccharides: Starch found in rice and pasta and
cellulose found in wholegrain breads and cereals
Fats
• Main function: Provide energy, provide insulation, supply fatsoluble vitamins and essential fatty acids
• Classified as: saturated, trans, monounsaturated and
polyunsaturated
• Food sources include
– Saturated: meat, butter, cream, coconut cream
– Trans: hydrogenated vegetable fats, manufactured margarines,
cakes and biscuits (also found naturally in smaller quantities in
meat and dairy)
– Monounsaturated: olives, olive oil, avocado, nuts
– Polyunsaturated: some margarines, vegetable oils, oily fish such
as salmon, tuna and sardines
Water
• Most important nutrient of all
• Essential for bodily functions, including:
digestion, absorption, circulation, regulation
of temperature, lubrication, transportation of
nutrients, oxygen and wastes
• Sources: fresh water, fruit and vegetables
Minerals
• Minerals are micronutrients, two important
minerals are calcium and iron
Calcium
• Main functions:
– forms hard structure of bones and teeth; regulates
contraction and relaxation of muscles; assists in
blood clotting; transmits nerve impulses
• Main sources:
– Milk and milk products, green leafy vegetables,
tofu and soy bean products, fish with edible bones
such as tinned tuna, nuts and seeds
Iron
• Main functions:
– Essential component of haemoglobin – the
pigment that gives blood its red colour
– Formation of red blood cells
• Sources:
– Red meat, chicken, seafood
– Wholegrain breads and cereals, legumes, dark
green leafy vegetables
Vitamins
• Vitamins are also micronutrients, they include:
– Vitamin A
– Vitamin D
– Vitamin C
– B-group vitamins such as thiamin, riboflavin,
niacin and vitamin B12
Vitamin A
Functions
Food sources
• Healthy vision
• Healthy skin
• Resistance to infection
• Maintaining the mucous membranes
that line the respiratory, gastrointestinal
and urinary tracts as well as the mouth
nose and ears
• Normal growth of children, particularly
teeth and bones
• Animal sources such as liver, oily fish,
full-cream milk, egg yolk and cheese
• orange and green fruit and vegetables
such as carrots, spinach, broccoli,
pumpkin, mango and apricots
Vitamin B
Functions
Food sources
• absorption and metabolism of calcium
and phosphorous to assist the formation
of bones and teeth
• cell growth and development
• healthy functioning of the nervous
system and the immune systems
• Fish, especially fish with a high fat
content, such as sardines and salmon
• meat, eggs and dairy products, including
butter
• fortified foods, such as margarine
Vitamin C
Functions
Food sources
• formation of collagen, the connective
tissue in skin, ligaments and bones
• promoting the healing of wounds
• absorption of iron / formation of red
blood cells
• preventing haemorrhaging and bleeding
gums
• fighting infection by maintaining white
blood cells, which act as bacteria fighters
• the production of thyroxin, a hormone
involved in metabolism
• Fruit and vegetables such as:
blackcurants, oranges, mangoes,
pineapples, grapefruit, kiwi fruit,
raspberries, capsicums, potatoes, broccoli
and spinach
Thiamin (vitamin B1)
Functions
Food sources
• Normal functioning of nerve cells
• Muscle tone
• fortified breakfast cereals
• yeast extracts (vegemite and marmite)
• liver
• kidney
• lean pork
• wholemeal bread
• sesame seeds
Riboflavin (vitamin B2)
Functions
Food sources
• Healthy skin and eyesight
• Involved in the production of red blood
cells
• yeast extracts (vegemite and marmite)
• liver
• lean red meat
• chicken
• fish
• milk and milk products
• eggs
• wholegrain breads and cereals
Niacin (vitamin B3)
Functions
Food sources
• blood circulation
• reducing cholesterol levels in the blood
• important for maintaining healthy
digestive tract
• yeast extracts (vegemite and marmite)
• wholegrain breads and cereals
• fortified breakfast cereals
• liver
• fish
• eggs
Pyridoxine (vitamin B6)
Functions
Food sources
• metabolism of protein
• production of red blood cells
• development of the nervous system
• liver
• lean red meat
• fish
• chicken
• wholegrain breads and cereals
Cyano-cobalamin (vitamin B12)
Functions
Food sources
• formation of red blood cells
• formation of nerve cells and DNA
genetic material
• metabolism of carbohydrates and fats
• liver
• kidney
• meat
• oysters
• fish
• seafood
• eggs
• milk