Download Chapter 4: Introduction to foods and nutrition

Journey through Health and Human Development 3rd Edition VCE Units 1 & 2
Chapter 4: Summary
Introduction to foods and nutrition
Nutrients for optimal youth development
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Food (liquid and solid form) is made up of nutrients that enable the body to function.
Remember you eat foods that contain nutrients rather than eating nutrients.
Classes of nutrients: proteins, carbohydrates (CHO), fats, water, vitamins and minerals.
Macronutrient (protein, fat, carbohydrates): a nutrient that is needed by the body in
relatively large amounts; intake can be measured in grams required per day.
Micronutrient (vitamins and minerals): a nutrient that is required by the body in small
amounts; intake can be measured in milligrams and micrograms per day.
Nutrients provide materials for:
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producing energy
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enabling growth
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maintaining and repairing body tissue
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regulating body processes
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preventing disease.
Protein
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Protein is made from amino acids (essential amino acids and non-essential amino
acids).
Function: necessary for the growth, maintenance and repair of body tissue.
Complete protein foods: contain all the nine essential amino acids in the correct
proportions and are mainly from animal food sources.
Incomplete protein foods: foods from plant sources that are missing or lacking the
required amount of one or more of the essential amino acids. They cannot be used by
themselves to support life.
Complementary protein food combinations: protein foods that are individually
lacking in essential amino acids but when combined, provide a complete supply. They
are important for vegetarians and allow them to receive all essential amino acids.
Carbohydrates
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Carbohydrates are made from units of sugar.
Function: body’s most important source of energy.
Three types of sugars: single sugars (for example, glucose, which is the main
carbohydrate in the body), double sugars (for example, sucrose or table sugar) and
chains of many sugars (for example, plants, cereals).
Glycaemic Index (GI): index that ranks (low, moderate or high) a food containing
carbohydrate by the speed at which the food raises blood glucose once eaten.
Low GI foods contain carbohydrates that are digested slowly and release their glucose
over a long period of time.
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Journey through Health and Human Development 3rd Edition VCE Units 1 & 2
Chapter 4: Summary
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High GI foods contain carbohydrates that are digested quickly and release their glucose
in a short period of time.
Fibre
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Fibre is a complex carbohydrate found in plants and remains mostly undigested—it is
not an energy source.
Function: important role in slowing down digestion in the small intestine and keeps the
digestive tract healthy and working regularly. Fibre reduces the formation of diverticuli.
Main types: insoluble fibre, soluble fibre (single sugar bonds not broken by digestive
enzymes), plus resistant starch (is left undigested).
Sources of soluble fibre: citrus fruits, oat products, barley, legumes, thickeners added to
food.
Sources of insoluble fibre: vegetables, fruits (especially skins), wholegrain cereals,
seeds.
Sources of resistant starches: raw potatoes, nearly ripe bananas, seeds, thickening
agents.
Fats
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Fats are made from fatty or oily compounds (fatty acids and glycerol) and are insoluble
in water.
Function: necessary to provide and store energy in the body, help in the absorption of
fat-soluble vitamins A, D, E and K and provide essential fatty acids for cell membranes.
Three main types of fats: saturated fats (‘bad fats’ associated with health issues),
unsaturated fats (‘good fats’ associated with a healthy diet) and trans fats (‘ugly fats’
and act like saturated fats).
Cholesterol is a fat (not a triglyceride) made by the liver and eaten in foods from
animal sources.
Function: part of the cell membranes allowing fat-soluble substances to move in and out
of the cell and is required for production of vitamin D, some hormones and bile salts.
Sources of saturated fats: fatty meat, eggs, whole milk, cheese, copha and palm oils.
Sources of unsaturated fats: mono (olive oil, peanut oil, sesame seeds), poly (vegetable
oils, oily fish, some nuts).
Sources of trans fats: deep-fried foods, cakes, biscuits, hydrogenated margarine.
Water
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Water is an essential component of all body tissues and an important part of every
function of the body.
Function: digestion, transportation, lubrication and elimination.
Sources: water-rich foods, for example fruits, vegetables.
There is no storage site for water in the body.
A person can only survive a few days without water.
Recommended water intake according to Kidney Health Australia is to satisfy thirst.
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Journey through Health and Human Development 3rd Edition VCE Units 1 & 2
Chapter 4: Summary
Vitamins
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Vitamins are organic substances.
Function: ensure optimal health, growth and functioning of the body and work with
enzymes to speed up chemical reactions, for example energy production.
Two main groups of vitamins: fat soluble and water soluble.
Fat-soluble vitamins (dissolved in fats): A, D, E, K are found in fatty and oily foods.
An adequate fat intake is required to ensure sufficient intake of fat-soluble vitamins.
Water-soluble vitamins (dissolve in water): eight B-group vitamins—including B6 and
B12, thiamin (B1), riboflavin (B2), niacin (B3)—C, folate, pantothenic acid and biotin.
Function and good sources of vitamins for youth development:
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Vitamin C—involved in the synthesis of collagen and other connective tissue
during the growth spurt. Sources include fruits, for example tomatoes,
blackcurrants, citrus fruits and vegetables, for example capsicums, potatoes, darkgreen vegetables such as broccoli, especially.
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B-group vitamins—help release energy from carbohydrates, fats and protein and
are important in the use of energy for activity and growth. B-group vitamins are
widely distributed through plant and animal sources.
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Vitamin A—needed for new cell formation in many tissues, helps with
reproduction and to ensure normal vision and reduces susceptibility to infection.
Sources include liver, meat, oily fish, fish oils, dark-green leafy vegetables such
as spinach, yellow-orange vegetables such as carrots, pumpkin and some fruits
including apricots.
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Vitamin D—essential for healthy bone development and achieving high bone
density during growth periods. Sources include sunlight along with oils, oily fish,
egg yolk.
Minerals
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Minerals are inorganic compounds needed in small amounts.
Function: to sustain healthy bones and blood and to maintain normal cell function.
Different minerals have different functions including working with enzymes to help in
chemical reactions, helping nerve impulses throughout the body, helping in the growth
and development of the body and ensuring in water balance.
At least twenty-two minerals play a role in human nutrition.
Important minerals for youth development:
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Calcium—ensures optimal bone density (approximately 90 per cent of adult bone
density by 17 years). Sources include dairy products (for example, milk, cheese)
vegetables, especially dark-green leafy vegetables, fish with bones, nuts and
seeds, and fortified soy drinks.
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Iron—supports rapid growth, the increase in blood volume and the increase in
muscle mass. Iron comes from animal sources including liver (very rich source),
beef, oysters, along with dark-green leafy vegetables and wholegrain cereals.
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Journey through Health and Human Development 3rd Edition VCE Units 1 & 2
Chapter 4: Summary
Interrelationship of major nutrients
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Food is made up of nutrients that interact with other nutrients to perform functions
within the body such as energy provision, growth, the development of bone density and
the formation of blood.
Nutrients required for energy provision
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Nutrients required for energy provision (for muscular activity, heat production etc.) in
youth development:
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Macronutrients—carbohydrates (16 kJ per gram), fats (37kJ per gram) and
proteins (17 kJ per gram).
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Micronutrients—iron, B-group vitamins and vitamin C.
Carbohydrates are the healthiest as the main source of energy with diets deriving more
than about 25 per cent of energy from protein associated with many chronic diseases.
Excess energy is taken in and stored as fat (adipose tissue) and when too little energy is
taken in, the body will use stored energy from adipose tissue and muscles.
Five factors affect the energy requirement of each individual: rate of growth, age, level
of activity, sex and body size.
Nutrients required for growth
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Nutrients required for growth in youth development:
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Macronutrients: protein, fats, water.
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Micronutrients: folate, vitamin A, vitamin C, vitamin D, calcium.
Nutrients are required to assist the growth of body tissues and during growth spurts
(rapid growth and development) when nearly every organ grows.
Body tissues are classified as soft and hard tissues:
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Soft tissue—collection of similar cells adapted to perform specific functions (for
example, muscles, blood, skin, nervous tissue).
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Hard tissue—collection of similar cells adapted to perform specific functions (for
example, bones, teeth and cartilage, which is semi-rigid support to structures like
the nose, ears and surfaces of the joints).
Collagen is the single most important protein substance that exists in many tissues of
the body, including bone, cartilage, skin and blood vessels. It is found in connective
tissue and serves as a matrix on which bone is formed.
Nutrients required for development of bone density
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Nutrients required for development of bone density in youth development:
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Minerals—60–66 per cent of bone weight provide strength with the remaining
34–40 per cent mainly water and protein.
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Calcium—major mineral (with phosphorous) found in bones.
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Fluoride—needed for healthy bones and teeth.
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Vitamin A.
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Vitamin D.
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Journey through Health and Human Development 3rd Edition VCE Units 1 & 2
Chapter 4: Summary
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Bone is a dynamic tissue made from blood vessels, nerve cells, fat, protein, minerals
(calcium, phosphorus).
Approximately 97 per cent of bone protein is collagen.
As bones grow, minerals are deposited in the soft framework of collagen causing bones
to become hard (calcification/mineralisation/ossification).
During calcification, bones increase in density and the more densely packed the
minerals, the stronger the bone tissue, resulting in healthy bone density.
Peak bone mass (PBM): time when a person’s body contains the greatest amount of
bone (from late childhood to early adulthood bone mass increases three-fold).
Bones continue to increase in mass until PBM is reached at 19–30 years. PBM is
maintained for 10–20 years before gradually declining with ageing.
Rate of decline in bone mass varies from person to person.
Weight-bearing exercise stimulates creation of new bone and slows the loss of bone
mass. This exercise causes the muscles to work against gravity and includes walking,
jogging, hiking, dancing, jumping rope, playing soccer, skating, lifting weights.
When no force is applied to bone it starts to lose bone mass.
Nutrients required for blood production
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Nutrients required for blood production in youth development:
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Macronutrients: protein, water.
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Micronutrients: iron, folate vitamin B12, vitamin C.
Blood is a liquid form of connective tissue that has cellular substances (red blood cells,
white blood cells and platelets) floating in a watery substance called plasma.
The component of red blood cells that carries the oxygen is called haemoglobin.
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